Health ConditionsXeroderma, also known as dry skin, xerosis cutis, or asteatosis, is a prevalent condition resulting from inadequate hydrolipids in the skin. Dry skin, known medically as xerosis cutis, is more than just a temporary discomfort; it is a common condition that can affect quality of life, leading to itching, flaking, and a compromised skin barrier. Dry skin should be seen as not a single condition but rather as a spectrum of conditions. At one end, subclinical aberrations are only demonstrable by skin physiological techniques such as evaporimetry or capacitance.
Dry skin (xerosis cutis) affects over 50% of adults, with a pooled prevalence of 53% (95% CI: 36%–69%), particularly common among older individuals and those in nursing homes or developed countries. Seasonal xerosis is common during the cold, dry winter months, and the frequency of xerosis increases with age.
Xerosis is characterized clinically by rough, scaly, and often itchy skin. This deficiency of hydrolipids can manifest as roughness, tightness, flaking, and scaling of the skin. Xerosis may appear scaly with accentuated skin lines, often occurring on the anterior legs, back, arms, abdomen, and waist. The scales are a result of epidermal water loss, and focal dryness may be deep enough to cause bleeding fissures.
Involved skin appears dehydrated, peeled, irritated, and inflamed. It feels rough, scaly, sometimes painful, and itchy. Severe conditions may be characterized by intense redness and itchiness; skin shows the tendency to crack, causing deep fissures that may bleed and are signs of extremely dry skin.
Superimposed pruritus is possible, leading to secondary excoriations, inflammation, and lichen simplex chronicus. Allergic and irritant contact dermatitis may also complicate xerosis. Untreated xerosis progresses to flaking, fissuring, inflammation, dermatitis, and infection.
Dry skin stems from a lack of moisture in the stratum corneum, the outermost layer of the skin. A healthy stratum corneum is composed of dead skin cells (corneocytes) embedded in a lipid-rich matrix of ceramides, cholesterol, and fatty acids. This structure acts as the body's primary environmental shield, known as the skin barrier. When this barrier is depleted of water and protective lipids, it loses its integrity, leading to increased transepidermal water loss (TEWL) and the classic symptoms of dryness, such as roughness, scaling, and itching.
The natural skin barrier consists of 15 to 20 layers of corneocytes embedded in a lipid intercellular substance, organized in a regular columnar pattern within the stratum corneum of the skin. As the outermost layer of the epidermis, the stratum corneum is the first line of defense for the body, serving an essential role as a protective skin barrier against the external environment. The stratum corneum aids in hydration and water retention, which prevents skin cracking, and is made up of corneocytes, which are anucleated keratinocytes that have reached the final stage of keratinocyte differentiation. Corneocytes retain keratin filaments within a filaggrin matrix, and the cornified lipid envelope replaces the keratinocyte plasma membrane. These flat cells organize in a brick-and-mortar formation within a lipid-rich extracellular matrix.
Three key deficiencies in the skin have been shown to contribute to xerosis. These include a deficiency in moisture-binding substances collectively known as the natural moisturizing factor (NMF); deficiencies in the skin barrier lipids, ceramides; and more recently, a deficiency of the skin's own moisture network in the viable epidermis, mediated by the newly discovered aquaporin water channels. NMF components are found exclusively in the stratum corneum and are located in high concentrations within the corneocytes.
The clinical severity of xerosis is directly correlated with reduced levels of natural moisturizing factors, such as water-soluble amino acids derived from profilaggrin breakdown. The lipid matrix of the stratum corneum contains cholesterol, ceramides, fatty acids, cholesterol sulfate, glucosyl ceramides, phospholipids, proteins, and enzymes.
Xerosis is characterized pathophysiologically by a disrupted stratum corneum, dehydration, and impaired keratinocyte differentiation. The reduction in intercellular lipid content and NMF that characterizes xerosis is both a cause and a consequence of abnormal epidermal differentiation. In fact, disruption of epidermal differentiation perpetuates the phenomenon of dry skin. Disruption of the epidermal barrier activates a metabolic response directed toward recovering epithelial homeostasis and reestablishing normal corneocyte differentiation. The main response is an increase in the biosynthesis of lipids, such as cholesterol, ceramides, and fatty acids.
Impairment of skin barrier function is often demonstrated by an altered integrity of the stratum corneum and a consequential increase in transepidermal water loss (TEWL). Skin barrier function impairment often arises from direct damage followed by a breach in the stratum corneum and/or a decrease in or dysfunction of stratum corneum lipids.
Humectancy is an important method for skin moisturization, where humectants function like sponges, drawing and retaining water within the skin. Within the dermis, glycosaminoglycans, including hyaluronic acid, serve as effective humectants. Additional humectants include glycerin, honey, sodium lactate, urea, and propylene glycol. Among these, glycerin is the most potent, which can draw water from the deeper epidermis and dermis layers of the skin, thereby filling gaps in the stratum corneum.
The stratum corneum must maintain a water content of at least 10% to remain pliable. When the lipid barrier is compromised, water loss accelerates. Results from foundational studies have shown that experimentally stripping the skin of its lipids can increase TEWL by up to 75-fold. This profound water loss results in the characteristic brittleness and cracking observed in this condition.
Slight disturbances of barrier function usually only affect the superficial epidermis, but repeated or severe damage gives rise to an inflammatory response that involves the deeper epidermal layers and even the endothelium. These phenomena give rise to abnormal keratinization and close the cycle that perpetuates the lesions. A similar mechanism may occur in hypoesthetic or denervated skin, where impaired autonomic regulation of sweat and sebum glands leads to severe localized xerosis and subsequent fissuring.
Exogenous factors that can contribute to xerosis include living in cooler climates, particularly during winter months, where both cold, dry air outdoors and indoor heating cause blood to be drawn away from the dermis, or in dry, hot climates, where constant heat and air conditioning evaporate water from the skin. Excessive bathing can also dry the skin. Many cleansers contain surfactants that extract and emulsify skin surface lipids and the intracellular lipids between the corneocytes of the epidermis, damaging the skin barrier.
The hallmarks of dry skin (xerosis) are scaliness and loss of elasticity. Decreased hydration and a disturbed lipid content of the stratum corneum are also well-known features. The frequency of dry skin increases with ageing. In aging skin, there is a significant decline in sebum-derived lipids within the stratum corneum, particularly triglycerides and free fatty acids.
In the elderly, metabolic changes, tendency to reduce liquid intake, associated with the physiological skin aging process — where keratinocytes move slowly from the basal layer of the epidermis to the stratum corneum and oil glands are less active — determine xerosis, thinning, and loss of elasticity. The aging process also results in dry skin (xerosis) because of a gradual decline in glycosaminoglycans within the dermis, which help form part of the structural network and in retaining dermal moisture.
Besides external causes and environmental triggers, there are endogenous or intrinsic causes of xerosis cutis such as aging, internal health conditions, dermatological and psychiatric diseases, diet, and drugs.
Diabetes mellitus: Fluctuations in blood sugar levels and changes in the body's water retention mechanisms caused by diabetes can disrupt the skin's natural moisture balance, frequently leading to dry skin in individuals with diabetes. Neuropathy, a complication of type 2 diabetes, aggravates skin symptoms in patients with diabetes. Neuropathy is associated with reduced sweating, which ultimately causes skin dryness, cracking, and impaired barrier function.
Thyroid disease: Hormone imbalances that occur in menopause, hypothyroidism, and hyperthyroidism can cause severe skin dryness. Thyroid hormones regulate many bodily functions, including the turnover of dead skin cells. When thyroid hormone levels are low, it takes far longer for dead skin cells to be shed and replaced by new ones, so skin looks dry and flaky.
Kidney disease: People in the later stages of kidney disease develop extremely dry, often itchy skin that feels rough and cracks easily. The cause is chronic dehydration and, in the end-stage of the condition, shrinking sweat and sebaceous glands.
Other systemic associations: Dry skin might be correlated to other skin diseases or associated with pathological conditions such as diabetes, hypothyroidism and hyperthyroidism, Sjögren syndrome, and malnutrition.
Xerosis in older adults is multifactorial: intrinsic changes in keratinization and lipid content, use of diuretics and similar medications, and overuse of heaters or air conditioners all contribute. Adverse drug effects are linked to diuretics, beta-blockers, contraceptives, retinoids, prolonged use of topical steroids, lipid-lowering agents, and radiation therapy.
This disorder is present in the course of some dermatoses such as atopic dermatitis, although it can also occur in healthy individuals if a combination of certain etiologic factors is present. Inherited ichthyoses, such as recessive X-linked ichthyosis, result from genetic defects that phenotypically present as skin scaling and diffuse xerosis. Recessive X-linked ichthyosis results specifically from steroid sulfatase deficiency that can affect the stratum corneum and clinically manifest with very dry skin and dark-colored scaling.
Cigarettes contain harmful chemicals that speed up how quickly skin ages, so skin becomes drier.
Certain vitamin and mineral deficiencies may be recognized by their cutaneous signs. These include deficiencies of zinc and vitamins A, B2, B3, B6, and C, each with consequences reflected in the skin. Malnutrition is associated with deficiencies in vitamins A and D, zinc, or iron.
Manifestations of vitamin A deficiency include night-blindness, dry eyes, and phrynoderma ("toad skin"). A lack of vitamin A can cause dry, scaly, and/or itchy skin. Retinol, an active form of vitamin A present in animal-derived foods, is essential in the regulation of the growth and differentiation of epidermal cells and the stimulation of collagen synthesis. Vitamin A deficiency classically impairs keratinocyte differentiation; vitamin A deficiency causes atrophy of the epithelial cells, proliferation of basal cells, and increased growth and differentiation of new cells into horny epithelium, resulting in symptoms of dryness and scaliness of the skin, and excessive keratinization.
Vitamin A deficiency should be considered in patients who present with follicular papules distributed symmetrically across the extensor surfaces. Inadequate dietary intake is the most common cause of deficiency. Additional risk factors include chronic malabsorptive disorders, such as inflammatory bowel disease (IBD) and cirrhosis.
Zinc deficiency can result from either inadequate diet or impaired absorption, which can be acquired or inherited. Zinc is closely associated with skin barrier integrity and immune function; periorificial dermatitis, also common in zinc deficiency, is characterized by red, scaly patches around orifices, and xerosis can accompany broader zinc-deficiency dermatoses. Although nutritional deficiencies are relatively uncommon in the general population, certain groups have a higher risk, including infants, pregnant women, alcoholics, vegetarians, persons of poor socioeconomic status, and patients on dialysis, on certain medications, or with a history of malabsorption or gastrointestinal surgery.
Biotin deficiency initially presents as gradual hair loss and dry skin. Cutaneous manifestations of biotin deficiency are mainly due to decreased fatty acid metabolism and present as alopecia, periorificial dermatitis, and skin infections. Risk factors for biotin deficiency include elderly age, pregnancy, alcohol abuse, smoking, medications such as phenobarbital and carbamazepine, and prolonged use of antibiotics.
The classic manifestations of vitamin C deficiency are scurvy and Barlow disease. Follicular papules, perifollicular hemorrhage, corkscrew hairs, and poor wound healing suggest vitamin C deficiency. Vitamin C plays a critical role in collagen synthesis and skin structural integrity; research has shown that the combination of vitamin A, vitamin C, and zinc leads to quicker recovery in wound healing, as vitamin C stimulates fibroblast proliferation while vitamin A and zinc assist in immune-related functions.
Traditional/historical context: Dietary fats — particularly those from fish, seeds, and plant oils — have been used for centuries across cultures to maintain skin suppleness. Fish liver oils were traditionally administered in northern European and Indigenous Arctic traditions for conditions including dry, cracked skin, though the explicit framing of these uses in terms of "omega-3" fatty acids is a modern scientific construct.
Scientific evidence: A 2018 systematic review offered early support for the topical use of fish oil-derived fatty acids such as linoleic acid (LA), alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). Evidence from cellular, animal, and human studies suggested such agents could enhance skin barrier integrity, diminish ultraviolet-induced inflammation and pigmentation, relieve itching associated with dermatitis, improve dry skin, and promote wound healing.
A 2025 systematic review, while acknowledging that evidence exploring the use of topical omega-3 in dermatological conditions remains limited, noted it has grown, including 19 articles encompassing in vitro mammalian skin models, preclinical animal models, and human studies. Overall, topical omega-3 use showed positive effects on improving skin conditions in psoriatic models, as well as reducing irritation and inflammation, enhancing wound healing, and improving hydration in almost all studies.
Regarding oral supplementation in a specific clinical population: supplementation with omega-3 PUFA significantly improved skin hydration on both the face and arms, as well as disease-related symptoms of pruritus in a trial of hemodialysis patients. Omega-3 PUFA supplementation improved inflammation, renal function, cardiovascular parameters, dry skin conditions, and the consequent symptoms of pruritus in hemodialysis patients. The trial used 1,000 mg fish oil (>900 mg EPA) daily for 3 months in 27 hemodialysis patients — a specific, highly vulnerable population, and findings cannot be directly extrapolated to the general population.
EPA-derived 12-hydroxyeicosapentaenoic acid (12-HEPE) has been shown to inhibit neutrophil infiltration by suppressing CXCL1 and CXCL2 expression in keratinocytes via the retinoid X receptor α pathway, reducing local inflammation. Evidence is preliminary and largely mechanistic; optimal dosages and delivery systems for omega-3 PUFAs remain uncertain.
Traditional use: Evening primrose (Oenothera biennis) is a plant related to the rosebay willow herb family. It is now grown as a cash crop, and its seeds are harvested to produce an oil. Evening primrose oil has been used in traditional North American herbal practice and subsequently entered 20th-century clinical interest as a source of GLA. Other rich natural sources of GLA are plant oils like borage seed oil, black currant seed oil, hempseed oil, and spirulina.
Proposed mechanism: As a consequence of impaired formation of GLA, endogenous production of prostaglandin E1 (PGE1) diminishes in atopic patients, leading to immune dysregulation and dominance of pro-inflammatory prostaglandins, eventuating in dermatitis. Evening primrose oil is a natural source of linoleic acid and GLA in relatively high concentration. Concentrations of linoleic acid tend to be elevated in blood, milk, and adipose tissue of patients with atopic eczema, whereas concentrations of linoleic acid metabolites are substantially reduced. This suggests reduced conversion of linoleic acid to gamma-linolenic acid (GLA). Atopic eczema may reflect a minor inherited abnormality of EFA metabolism.
Scientific evidence — mixed and largely negative for atopic dermatitis: A 2013 Cochrane review of 27 randomized controlled trials involving a total of 1,596 participants found that evening primrose oil and borage oil taken orally had no clinical benefit for the treatment of atopic eczema. A systematic review for the NHS Health Technology Assessment programme, encompassing fifteen studies (ten on evening primrose oil and five on borage oil), found that the largest and best-reported studies did not show convincing evidence of any benefit, and a subsequent double-blind RCT of high-dose GLA capsules in 151 people with atopic dermatitis found no statistically significant benefit for GLA supplementation compared with placebo.
According to the American Academy of Dermatology's clinical practice guidelines, there is inconsistent to no evidence to recommend the use of fish oils, evening primrose oil, borage oil, multivitamin supplements, zinc, vitamin D, vitamin E, and vitamins B12 and B6 for the treatment of atopic dermatitis. Evidence strength: For GLA-rich oils in atopic dermatitis-related dry skin, the overall evidence from high-quality Cochrane-level reviews is negative. Evidence for general population xerosis remains insufficient.
Traditional use: Gelatin and collagen-rich broths derived from animal bones, skins, and connective tissues have been consumed across many food cultures for centuries. The direct association between such foods and skin moisture is a traditional folk observation rather than a formally documented traditional medicine indication.
Scientific evidence — mechanistic basis: Orally ingested hydrolyzed collagen is absorbed as di- and tripeptides (e.g., Pro-Hyp, Gly-Pro-Hyp) that act as signaling molecules to activate dermal fibroblasts, upregulate hyaluronic acid synthesis, and stimulate expression of collagen types I and III. These peptides also inhibit MMP-1 and MMP-3, reducing collagen degradation, particularly under UV or oxidative stress conditions.
Clinical trial evidence — conflicting: Several meta-analyses of RCTs have been published with differing conclusions. One systematic review and meta-analysis of 10 RCTs (646 participants) found that collagen supplements were statistically effective in increasing skin hydration (SMD 1.25, CI: 0.77–1.74) and elasticity (SMD 0.61, CI: 0.21–1.02). The findings of this study revealed that hydrolyzed collagen supplementation can improve skin hydration and elasticity, and long-term use yields more favorable effects on skin hydration and elasticity than short-term use.
However, a more recent and larger meta-analysis of 23 RCTs (1,474 participants) reached a contrasting conclusion: in a meta-analysis of all 23 RCTs, collagen supplements significantly improved skin hydration, elasticity, and wrinkles. However, in the subgroup meta-analysis by funding source, studies not receiving funding from pharmaceutical companies revealed no effect of collagen supplements for improving skin hydration, elasticity, and wrinkles, while those receiving funding from pharmaceutical companies did show significant effects. Similarly, high-quality studies revealed no significant effect in all categories, while low-quality studies revealed a significant improvement in elasticity.
In this meta-analysis, unlike previous meta-analyses, the investigators found that collagen supplements had no beneficial effect on skin aging in the meta-analysis of high-quality studies and nonfunded studies from pharmaceutical companies. This was the first systematic review and meta-analysis to report no effect of collagen supplements on skin aging. Evidence strength: Overall evidence is mixed and substantially complicated by industry funding bias. Independent, high-quality trials show no significant effect; further large-scale, independently funded RCTs are needed.
Background: Within the dermis, glycosaminoglycans, including hyaluronic acid, serve as effective humectants. High-molecular-weight (HMW) hyaluronic acid contributes predominantly to skin hydration by forming a viscoelastic network that binds water molecules while also providing structural stability to the extracellular matrix and exerting anti-inflammatory properties.
Traditional use: No documented traditional herbal use exists for hyaluronic acid per se — it is a compound identified and isolated through modern biochemistry. Its interest is entirely scientific in origin.
Scientific evidence: In a randomized, double-blind, placebo-controlled clinical study it was found that ingested hyaluronic acid increased skin moisture and improved treatment outcomes for patients with dry skin (Kawada et al., Nutrition Journal, 2014). Skin ageing is characterised by a decrease in the levels of collagen, elastin fibre, and hyaluronic acid, resulting in a loss of skin elasticity and hydration. Prior studies suggest that oral collagen supplements can help increase collagen, elastin, and HA levels, ultimately improving skin health. HA has also been shown to attenuate oxidative stress and facilitate the repair of damaged tissues, reinforcing its significance in maintaining overall skin health. Evidence strength: Preliminary to moderate; several small RCTs suggest benefit, but larger independent trials are needed.
Background: Ceramides are lipids naturally present in the skin that make up approximately 50% of all lipids in the epidermis by weight. They are composed of sphingosine and fatty acids and are known to play an important role in skin elasticity and maintaining the water permeability barrier function of the skin. Ceramides help with the formation of the cutaneous barrier to keep the skin hydrated and are thought to protect the skin from external aggressions and insults such as pollution, toxins, and environmental irritants and allergens.
Traditional use: No traditional herbal use applicable — ceramides as a defined compound category are a modern discovery. However, plant-derived foods rich in glycosylceramides (wheat, rice, konjac) have been consumed traditionally, though not for skin-specific purposes.
Scientific evidence — topical: When applied topically for 21 days, a ceramide-containing formulation significantly reduced transepidermal water loss (TEWL) in patients with very dry skin compared to their TEWL baseline data, demonstrating effectiveness in restoring skin homeostasis and barrier function in damaged skin.
Scientific evidence — oral: Although foregoing evidence supports beneficial effects of topical ceramides for restoration of the skin barrier, studies on oral ceramides are extremely scarce, with most published data collected from in vivo and in vitro models. During the recent past, studies have demonstrated the beneficial effects of orally supplemented ceramides against dry skin, skin aspect, and associated discomforts. Dietary glycosylceramides are metabolized in the rat small intestine and found in portal blood after hydrolysis by ceramidases in the gastrointestinal tract. A large proportion of ingested sphingolipids are excreted in the feces, though animal studies suggest that after oral intake, radiolabeled ceramides are metabolized, absorbed, and distributed to many tissues, including the skin. One study showed that orally administered radiolabeled sphingosine is transferred to the skin and generates glucosylceramides and ceramides in vivo in mice. Evidence strength: Topical ceramides have reasonable clinical evidence; oral ceramide evidence is preliminary, based largely on animal and small open-label human studies.
Traditional use: Vitamin B3 (niacin/niacinamide) is a dietary nutrient found in meat, poultry, fish, nuts, and legumes. Its severe deficiency produces pellagra — historically epidemic in populations dependent on maize — which includes dermatitis as a cardinal sign. The use of niacinamide specifically for dry skin as a topical or oral supplement is a modern clinical development.
Scientific evidence: Topical niacinamide has been shown in randomized clinical trials to augment ceramide, free fatty acid, and cholesterol synthesis in keratinocytes, thereby improving the skin barrier. Tanno et al. showed that in cultured human epidermal keratinocytes, nicotinamide could upregulate the synthesis of major components of skin barriers, such as ceramide and other sphingolipids. Niacinamide is widely used in skincare for its favorable safety profile, anti-aging effects, and proven clinical efficacy in treating various skin conditions. However, its direct impact on the hydration and molecular organization of the stratum corneum remains an area of ongoing investigation. Research has examined how niacinamide influences the stratum corneum's lipid matrix organization, soft keratin structure, and water sorption behavior across varying relative humidity levels. Evidence strength: Mechanistic in-vitro and clinical evidence for topical niacinamide in skin barrier support is reasonably well established; oral supplementation for dry skin specifically has less direct human trial evidence.
Traditional use: Aloe barbadensis (aloe vera) has been used topically for millennia in Egyptian, Greek, Roman, Ayurvedic, and traditional Chinese medicine for burns, wounds, and dry or irritated skin. The gel from the leaf's inner pulp was applied directly to affected skin in these traditions.
Scientific evidence: Active compounds such as polysaccharides in aloe vera exhibit significant anti-inflammatory, antioxidant, and immune-modulating properties. In the context of dry skin associated with pruritic conditions, aloe vera polysaccharides are among the plant compounds studied for antipruritic effects. However, in a 2011 PubMed-indexed review on xerosis in the elderly, care was made to avoid skin sensitizers, such as lanolin, aloe vera, and parabens, that are commonly found in emollients, as these may lead to a delayed hypersensitivity reaction. Evidence strength: Largely traditional and mechanistic; clinical trial evidence specifically for xerosis cutis is limited, and potential for contact sensitization has been noted in the literature.
Traditional use: Chamomile (Matricaria chamomilla) and calendula (Calendula officinalis) are among the medicinal plants investigated for their antipruritic potential.
Scientific evidence: Chamomile and calendula alleviate itching through anti-inflammatory and skin-soothing effects. These findings derive principally from in vitro studies and small clinical investigations reviewed in the context of antipruritus, a symptom commonly associated with dry skin; large, well-controlled RCTs specifically targeting xerosis cutis with these botanicals are not established in the peer-reviewed record. Evidence strength: Preliminary; mechanistic and traditional, with limited high-quality RCT data for xerosis specifically.
Associations between daily amounts of drinking water and skin hydration receive increasingly attention in daily life and in clinical practice. However, there is a lack of evidence of dermatological benefits from drinking increased amounts of water.
A 2018 systematic literature review (Akdeniz et al., Skin Research and Technology) searched PubMed and Web of Science, ultimately including six eligible studies: The mean age of the samples ranged from 24 to 56 years. Overall, the evidence was weak in terms of quantity and methodological quality. Disregarding the methodological limitations, a slight increase in stratum corneum and "deep" skin hydration was observed after additional water intake, particularly in individuals with lower prior water consumption. Reductions of clinical signs of dryness and roughness were observed. The extensibility and elasticity of the skin increased slightly. Unclear associations were shown between water intake and transepidermal water loss, sebum content, and skin surface pH.
Normal skin hydration increases with dietary water intake, particularly in those with prior lower water consumption. Additional dietary water intake may increase stratum corneum hydration. The underlying biological mechanism for this possible relationship is unknown. Whether this association also exists in aged subjects is unclear. Evidence strength: Weak overall. The effect of additional water intake on stratum corneum hydration appears limited and most relevant to individuals with habitually low fluid intake.
The quality and composition of dietary fat intake has implications for skin barrier lipid composition. A 2012 Cochrane review of 11 randomized controlled trials of dietary supplements — including fish oil, vitamin D, vitamin E, vitamin B6, sea buckthorn oil, hempseed oil, sunflower oil, DHA, selenium, and zinc sulfate — found no convincing evidence of their benefit for atopic eczema. This review, while focused on atopic eczema rather than general dry skin, represents the most rigorous appraisal of multiple dietary supplement interventions in a dry-skin-associated condition.
Diet is recognized as an endogenous or intrinsic cause of xerosis cutis, and malnutrition is associated with deficiencies in vitamins A and D, zinc, or iron — all nutrients whose deficiency can contribute to compromised skin barrier function and dryness.
Excessive bathing can dry the skin. Many cleansers contain surfactants that extract and emulsify skin surface lipids and the intracellular lipids between the corneocytes of the epidermis, damaging the skin barrier. This is a well-supported lifestyle factor in the literature on xerosis management.
Dry scaly skin with its associated barrier and water-holding capacity problems occurs not just in pathological states — it also occurs in the general population, especially the aged, and in virtually all those living and working in low-humidity climates. Patients can minimize the effect of xerosis by increasing the ambient humidity, modifying their bathing technique and products, and using emollients to replace the lipid components of the skin.
Lifestyle health factors discussed in the literature as relevant to dermal health include nutrition/diet, rest (sleep), movement/physical exercise, and social and community associations. However, evidence linking specific sleep or exercise interventions to measurable improvements in xerosis cutis per se is not strongly established in the peer-reviewed record.
The prevalence of xerosis increases with age; this is thought to be caused by changes in the keratinization process and lipid content of the stratum corneum. In aged populations, multiple concurrent nutritional gaps may interact with physiological changes to worsen skin dryness. Certain groups — including elderly individuals, pregnant women, alcoholics, vegetarians, persons of poor socioeconomic status, and patients on dialysis, on certain medications, or with a history of malabsorption or gastrointestinal surgery — have higher risk of clinically relevant nutritional deficiencies with cutaneous manifestations.
Acemannan is the primary bioactive polysaccharide from Aloe vera gel, acting as a humectant and water-retaining agent in the stratum corneum. It is responsible for the moisture-binding activity of aloe gel and supports skin barrier function. Evidence from aquaporin-3 upregulation studies and clinical aloe research directly implicates acemannan in dry skin improvement.
Alpha-linolenic acid (ALA) is a plant-based essential omega-3 fatty acid that supports skin barrier function and hydration. Essential fatty acid deficiency (including ALA) causes dry, scaly skin, and supplementation reverses this. Evidence from cellular, animal, and human studies confirms topical ALA can improve skin barrier integrity and reduce dry skin.
Allantoin acts as a humectant and keratolytic agent, increasing water content in the stratum corneum and reducing transepidermal water loss (TEWL). The FDA recognizes allantoin as an OTC skin protectant at 0.5–2%, and clinical formulations containing allantoin have demonstrated measurable improvements in skin hydration. It is widely incorporated into moisturizer products for dry skin conditions.
Clinical evidence from RCTs in postmenopausal women shows that almond consumption improves skin hydration measures and reduces transepidermal water loss (TEWL). Almonds' high content of essential fatty acids and vitamin E are proposed to support the skin lipid barrier and reduce moisture loss.
Aloe vera gel is traditionally used across multiple cultures for dry, irritated skin and scientifically confirmed to improve skin hydration. In vivo studies show topical aloe increases skin moisture and reduces TEWL via its mucilaginous polysaccharide acemannan. Clinical research also demonstrates aloe extract upregulates aquaporin-3, the water channel responsible for stratum corneum hydration.
Alpha hydroxy acids (AHAs) such as lactic acid and glycolic acid treat dry skin by promoting desquamation of thickened, accumulated dead corneocytes and improving stratum corneum hydration via humectant properties. Lactic acid is a natural moisturizing factor component that directly increases skin water content. Multiple clinical dermatology studies confirm AHAs improve xerosis and skin smoothness.
Human clinical data in postmenopausal women show that both topical and oral argan oil significantly reduce transepidermal water loss (TEWL) and improve skin hydration. It is a well-supported moisturising agent for dry skin.
Multiple studies confirm that topical ascorbyl palmitate has significant moisturizing activity. A PubMed-indexed study found that AP in solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) hydrogels moisturized skin significantly better than placebo in both short-term (p<0.001) and long-term trials (p<0.01). AP's hydrophilic palmitate moiety is believed to contribute to its skin-conditioning properties.
Oral borage seed oil supplementation has been shown in a controlled human study to significantly improve skin barrier function in elderly subjects, as measured by reduced transepidermal water loss (TEWL). GLA is required for normal epidermal barrier lipid synthesis, and supplementation compensates for age-related decline in delta-6-desaturase activity.
Borage oil contains at least 23% gamma-linolenic acid (GLA)—approximately 2–3x more than evening primrose oil—and is used to address dry and atopic skin by restoring skin barrier lipids. Placebo-controlled double-blind studies show modest improvements in skin hydration and dry skin symptoms. Its GLA content bypasses the impaired delta-6-desaturase step associated with dry/atopic skin.
Calendula is incorporated into a large number of cosmetic emollient formulations for dry and sensitive skin. The EMA recognises it for minor skin inflammation and wound healing, which includes compromised barrier function seen in dry skin. Clinical use is well-established, with hydrating and soothing properties attributed to mucilaginous polysaccharides and carotenoids.
Beta-carotene from carrots is converted to vitamin A (retinol), which is essential for skin cell turnover, epithelial maintenance, and sebaceous gland function. Vitamin A deficiency causes xerosis (dry, scaly skin), and adequate beta-carotene intake supports skin hydration and barrier integrity.
Ceramides are lipids naturally comprising ~50% of stratum corneum lipids; their depletion causes dry, barrier-disrupted skin. Multiple RCTs and a 2021 systematic review (12 comparative studies) confirm topical ceramide formulations improve skin hydration and repair barrier function in dry skin and xerosis. Oral ceramide supplementation has also shown hydration benefits in clinical trials.
Clinical trials and in vitro studies show cacao powder significantly improves skin hydration and moisture retention. A 12-week RCT demonstrated significant improvement in skin hydration after cacao powder consumption. In vitro, cacao powder promotes hyaluronic acid production in keratinocytes and reduces transepidermal water loss.
Level 1 RCT evidence demonstrates topical VCO is effective for xerosis (clinically dry skin), performing comparably to or better than mineral oil. A WHAM evidence summary assigned Grade B recommendation for VCO in mild-to-moderate xerosis. Application twice daily to affected areas is the established dosing protocol.
Topical application of virgin coconut oil—pressed from coconut milk—has demonstrated efficacy comparable to mineral oil for treating dry skin in clinical studies. It reduces transepidermal water loss (TEWL) and provides barrier protection for the stratum corneum. Clinical studies have shown VCO improves skin hydration and moisture markers.
Multiple RCTs have confirmed that topical virgin coconut oil effectively moisturizes dry skin, reduces transepidermal water loss (TEWL), and improves skin barrier function. A double-blind RCT in 117 pediatric atopic dermatitis patients found VCO superior to mineral oil on SCORAD scores, TEWL, and skin capacitance over 8 weeks. Coconut oil is widely used in tropical-region traditional medicine as a moisturizer.
Omega-3 fatty acids from cod liver oil maintain skin barrier function and hydration by being incorporated into epidermal phospholipids. Vitamin A supports skin cell turnover and barrier integrity. Both nutrients are associated with improved skin moisture and reduced transepidermal water loss.
Oral hydrolyzed collagen peptides improve skin hydration in multiple randomized double-blind placebo-controlled trials and meta-analyses. Collagen peptides stimulate dermal fibroblast synthesis of new collagen, elastin, and hyaluronic acid, reducing TEWL and improving dry skin. A 12-week RCT (n=64, 1000 mg/day) showed significantly higher skin hydration values versus placebo at 6 and 12 weeks.
Alpha-tocopherol is the predominant antioxidant in the stratum corneum and has well-established moisturizing and barrier-supporting properties in skin. Its sebaceous delivery system maintains epidermal lipid integrity, and topical application is broadly documented to reduce transepidermal water loss and support barrier function in dry and compromised skin.
DHA is a long-chain omega-3 PUFA from fish and microalgae that integrates into skin cell membranes, improving membrane fluidity and barrier function and reducing TEWL. Systematic reviews and clinical studies confirm DHA-containing preparations improve dry skin and enhance barrier integrity. Together with EPA, DHA reduces pro-inflammatory mediators that compromise skin barrier hydration.
EPA contributes to skin barrier integrity by modulating epidermal lipid composition and suppressing inflammatory eicosanoids that degrade the stratum corneum. Clinical and mechanistic studies link adequate omega-3 status, particularly EPA, to improved skin hydration and reduced transepidermal water loss.
EPA is a long-chain omega-3 PUFA from fish and algae with well-documented anti-inflammatory effects directly relevant to skin barrier dysfunction and dry skin. EPA-derived mediators inhibit pro-inflammatory neutrophil and keratinocyte signaling that drives barrier compromise and dryness. Clinical studies and systematic reviews confirm EPA supplementation improves skin moisture and barrier function.
Evening primrose oil (EPO) contains 8–10% gamma-linolenic acid (GLA) and has been widely studied for dry skin and atopic eczema. RCTs show EPO reduces TEWL, improves skin hydration, and decreases objective eczema scores; GLA plasma levels correlate with clinical improvement. It has been used as both a prescription and OTC remedy for dry, scaly skin.
Omega-3 PUFAs from fish oil are structural components of the skin's lipid barrier and modulate cutaneous inflammation. Clinical evidence shows fish oil supplementation improves skin moisturization and reduces pruritus in conditions associated with dry skin. A prospective cohort study in hemodialysis patients (n=31) found 1,000 mg/day fish oil for 3 months significantly improved skin moisture and reduced inflammatory pruritus.
A clinical trial found that 12 weeks of flaxseed oil supplementation significantly improved skin hydration, sensitivity, roughness, and smoothness. Clinical results of PUFA supplementation on skin barrier parameters (hydration, transepidermal water loss, roughness) are documented in peer-reviewed dermatology literature.
GLA is an omega-6 fatty acid from evening primrose, borage, and blackcurrant oils that restores skin barrier lipids impaired by delta-6-desaturase deficiency in dry/atopic skin. Clinical studies confirm GLA plasma levels correlate with dry skin improvement, and supplementation reduces TEWL and inflammatory barrier dysfunction. GLA converts to DGLA, producing anti-inflammatory prostaglandins that support skin hydration.
Glycerin (glycerol) is one of the most well-established humectants for dry skin, attracting and retaining water in the stratum corneum. Scientific studies confirm it improves skin moisture content, elasticity, and barrier properties. Research has elucidated its mechanism via aquaporin-3 channels and demonstrated its concentration-dependent moisture-retention capacity.
Glycosylceramides are plant-derived ceramide precursors that improve skin hydration when taken orally. A randomized clinical study of Konjac-derived glucosylceramides demonstrated improved skin moisture and reduced dry skin discomfort. Orally administered glycosylceramides are hydrolyzed to ceramides in the intestine, absorbed, and distributed to the skin.
Honey's humectant, emollient, and antimicrobial properties support skin hydration and barrier function. Reviews of honey phytochemicals (2024, Phytotherapy Research) document its skin barrier-enhancing, anti-inflammatory, and wound-healing properties. Clinical studies of honey in atopic dermatitis (a condition marked by dry, inflamed skin) have shown benefit.
Hyaluronic acid (HA) is a key endogenous skin humectant capable of binding up to 1000x its weight in water. Multiple randomized double-blind placebo-controlled trials confirm that both topical and oral HA significantly improve skin hydration and reduce dry skin symptoms. A 12-week RCT (n=40) found significantly higher stratum corneum water content in the HA group vs. placebo.
In vivo human volunteer studies using H. italicum extract-impregnated textiles confirmed improvements in skin electrical capacitance (hydration) and reductions in transepidermal water loss, supporting its skin-moisturising and barrier-protective effects.
Two 2024 randomized, double-blind, placebo-controlled pilot studies (Handeland et al., PMID 39169540; n=51 and n=50 healthy adults) found that 1 g and 2 g of krill oil/day for 12 weeks produced significant, dose-dependent reductions in transepidermal water loss (TEWL) and improvements in skin hydration compared to placebo. Effects correlated linearly with increases in the omega-3 index.
Linoleic acid (LA) is an essential omega-6 fatty acid that is the obligatory component of skin acylceramides; LA deficiency causes dry, scaly skin with elevated TEWL. Topical LA replenishes stratum corneum ceramide fractions and restores barrier function. Systematic review evidence confirms topical LA-rich preparations enhance skin barrier integrity and improve dry skin.
Marshmallow root mucilage forms a moisture-retaining film on skin, documented in clinical and in vitro research. A human study found a 20% marshmallow root extract ointment significantly reduced skin irritation and improved hydration. Its polysaccharides support skin barrier function and moisture retention.
Oral and topical NAG has demonstrated improvements in skin moisture content in placebo-controlled clinical studies. NAG serves as a direct precursor to hyaluronic acid (HA) biosynthesis, driving skin hydration. An 8-week double-blind placebo-controlled trial in women with habitually dry skin found significant improvement in stratum corneum moisture content at 500 mg/day oral NAG.
Colloidal oatmeal is an FDA-approved OTC skin protectant with well-documented clinical efficacy for dry skin. Multiple clinical studies and a large retrospective analysis confirm improvements in dryness, roughness, desquamation, and transepidermal water loss with colloidal oatmeal-containing products.
Oleic acid is a major constituent of the skin's natural lipid barrier and is used topically to replenish lost lipids and improve skin hydration. It penetrates deeply into skin layers and helps restore barrier function. Clinical and ex-vivo studies confirm that unsaturated fatty acids including oleic acid contribute to maintaining and restoring the skin's lipid barrier.
Topical olive oil has been traditionally and clinically used to moisturize dry skin, with its fatty acid composition providing occlusive and emollient properties. However, RCT evidence shows that while olive oil can temporarily improve hydration, its high oleic acid content may increase transepidermal water loss with prolonged use on some skin types.
Omega-3 fatty acids (primarily EPA and DHA) integrate into skin cell membrane phospholipids, improving barrier function and reducing TEWL. Clinical supplementation studies demonstrate increased skin hydration within 8–12 weeks and reduced inflammatory barrier dysfunction. Systematic reviews confirm topical and oral omega-3 PUFAs improve dry skin.
Linoleic acid (LA) is an essential structural component of skin ceramides and is required for formation of the epidermal water-permeability barrier. Deficiency of dietary omega-6/LA leads to transepidermal water loss, scaly dermatoses, and dry, disrupted skin. Both oral supplementation and topical application of omega-6-rich oils have documented effects on skin hydration and barrier function.
Oral and topical sea buckthorn oil, containing omega-7 palmitoleic acid, has demonstrated skin hydration improvements in controlled trials. A 12-week randomized, double-blind, placebo-controlled study (n=90) using 500 mg/day oral palmitoleic acid significantly improved skin hydration and reduced transepidermal water loss (TEWL) versus placebo. A topical sea buckthorn lotion RCT in healthy males also showed significant skin hydration improvements over 8 weeks.
Ophiopogon root polysaccharides physically retain moisture and repair skin barrier function, and this is supported by in vitro and cosmetic science evidence. The β-fructan polysaccharides reduce nitric oxide and inflammatory pathways while hydrating the skin. A clinical study with oligofructosane fractions from O. japonicus demonstrated benefit in atopic dermatitis — a condition defined by pathological skin dryness.
Palmitic acid is a natural component of the skin's lipid barrier, alongside ceramides and cholesterol. Applied topically, it functions as an emollient that forms a protective film, prevents transepidermal water loss, and supports the stratum corneum barrier against dryness, irritants, and allergens. It is widely used in dermatological formulations for dry skin at concentrations of 5–15%.
POA is a native component of the viable epidermis that supports the skin lipid barrier. A 12-week RCT in 90 women showed oral POA supplementation (500 mg/day) significantly improved skin hydration and reduced transepidermal water loss compared with placebo.
Panthenol (provitamin B5) is a clinically validated skin humectant and conditioning agent converted to pantothenic acid in the skin, where it supports ceramide synthesis and barrier function. Clinical studies confirm panthenol-containing formulations (1–5%) significantly increase skin moisture content and reduce TEWL. It is recognized as a skin-conditioning humectant by cosmetic safety regulatory authorities.
RCT evidence shows Pycnogenol supplementation improves skin hydration and elasticity, particularly in women with dry skin. Six weeks of supplementation increased hydration by 21% in dry-skin subjects vs. 8% in normal-skin subjects. Mechanisms include upregulation of hyaluronic acid synthase and collagen type I synthesis.
Rosehip preparations—both topical and oral—have demonstrated improvements in skin moisture in clinical trials. An 8-week double-blind RCT in 34 subjects showed standardized rosa canina powder increased forehead moisture content. Rosehip oil, rich in essential fatty acids, supports the skin barrier and reduces transepidermal water loss.
Topical sesame oil has been shown in a human study (35 volunteers, average age 20) to increase skin hydration by nearly 30% after a single application. Sesame oil's fatty acid composition (particularly oleic acid) forms a barrier film on the epidermis that reduces transepidermal water loss. It is widely used as an emollient in dermatology and traditional medicine.
Shea butter is one of the most clinically supported natural emollients for dry skin. It reduces transepidermal water loss (TEWL) significantly within hours of application and increases skin hydration measurably over weeks. Its fatty acid profile closely mirrors the skin's natural lipid composition, reinforcing the stratum corneum barrier.
Squalene is a major natural component of human sebum (~12–13%), where it contributes to skin hydration and barrier integrity. Its hydrogenated form (squalane) has been studied in clinical and ex-vivo contexts, demonstrating reduced transepidermal water loss (TEWL) and restored skin barrier function. Squalene production declines from the mid-twenties onward, contributing to age-related dryness. Topical formulations containing squalane are used to replenish this deficit.
Sunflower seed oil is a well-documented skin emollient that significantly reduces transepidermal water loss (TEWL) and improves hydration. A 2018 clinical study demonstrated sunflower oil improved skin hydration in adults without irritation. Its high linoleic acid content helps maintain the stratum corneum lipid barrier and locks in moisture.
Clinical studies demonstrate that topical sunflower oil reduces transepidermal water loss (TEWL), improves skin hydration, and maintains the skin barrier, making it effective for dry skin. A human study of 19 volunteers found sunflower oil superior to olive oil in improving skin hydration and maintaining the skin's outer layer integrity. It is evidenced for xerosis and dry skin in adults.
Vitamin A and its retinoid derivatives are established regulators of keratinocyte differentiation and epidermal barrier function. Deficiency causes xerosis (dry, scaly skin) and follicular hyperkeratosis. Topical retinoids improve skin hydration, texture, and barrier integrity, supported by multiple clinical studies.
Niacinamide (vitamin B3 amide) strengthens the skin barrier by stimulating ceramide, fatty acid, and natural moisturizing factor synthesis in keratinocytes, thereby reducing TEWL and improving skin hydration. Clinical RCTs and JAAD studies confirm niacinamide-containing formulations improve barrier recovery in dry skin. It is a standard ingredient in dermatologist-recommended dry skin moisturizers.
Topical dexpanthenol (provitamin B5) has been shown in clinical studies to reduce transepidermal water loss (TEWL) and improve skin hydration. Its activity is linked to its role as a CoA precursor driving ceramide and fatty acid synthesis in the epidermis. Dexpanthenol cream has also been studied to manage xerosis during isotretinoin therapy.
Vitamin E (tocopherol) is a lipid-soluble antioxidant that protects skin cell membranes from oxidative damage contributing to dryness. Clinical and in vitro studies confirm topical vitamin E improves skin moisture content, reduces roughness, and supports barrier function in dry skin. It has a long established use in dermatology as a moisturizing and barrier-supportive ingredient.
Wheat germ oil is readily absorbed by human skin and is rich in vitamin E, linoleic acid, and other unsaturated fatty acids that restore the skin barrier and seal moisture. It has been used topically as a moisturizer with a scientifically grounded mechanism. Clinical dermatology supports its use for dry and cracked skin.
Apricot kernel oil is a traditional topical emollient used for centuries in Central and South Asian cosmetic traditions to soften and moisturize dry skin. The oil is rich in oleic and linoleic acids, which support skin barrier function. Vitamin A precursors in the fruit support epithelial cell turnover. Commercial apricot kernel oil remains widely used in cosmetic formulations for dry skin.
Chickweed is a well-established traditional topical remedy for dry, irritated skin due to its demulcent mucilage content. Applied as creams, salves, or infused oils, it is considered to moisturize and soothe dryness. No clinical trials exist specifically for dry skin.
Cottonseed oil has documented traditional use as a topical skin moisturizer and emollient, particularly in Ayurvedic traditions and in Tamil Nadu where cottonseed milk (paruthi paal) is a skincare staple. Its linoleic acid content is mechanistically relevant to skin barrier maintenance. A 2025 review in Frontiers in Pharmacology noted CSO's linoleic-to-oleic acid ratio supports skin barrier function, though direct clinical trials on dry skin are lacking.
Cucumber has a long history of topical use for dry, irritated skin across Ayurvedic and European folk traditions. Its high water content and the presence of silica are proposed to support skin hydration. Cucumber extract is a recognised cosmetic ingredient used in moisturising formulations.
Eicosenoic acid (C20:1) is the dominant fatty acid in meadowfoam seed oil (comprising approximately 61% of its fatty acid content) and is also found in jojoba oil. These oils are widely used as emollients in cosmetic and topical skin-care formulations for moisturization and skin conditioning. The emollient, permeation-enhancing, and soothing properties attributed to eicosenoic acid in this context are based on traditional and cosmetic use rather than controlled clinical trials specifically on the isolated fatty acid.
Geranium EO is traditionally used in skin-care preparations for its moisturizing and sebum-balancing properties. It is recognized in herbal medicine for improving dry and mature skin conditions. No clinical trial evidence is available for this specific indication.
In TCM, glehnia root is considered a yin-nourishing herb that addresses dryness-related conditions including dry skin, attributed to 'lung yin deficiency.' Tibetan medicine also records its use for skin diseases. No clinical trials have examined topical or systemic effects on skin.
In TCM, lily bulb is traditionally described as promoting vital fluids and improving skin complexion, attributed to its high mucilage and vitamin content. It is documented as a skin-beautifying herb in classical texts. Modern research confirms lily extracts possess antioxidant and antimicrobial activities relevant to skin health and are increasingly incorporated into dermatocosmetic formulations.
Macadamia nut oil has a longstanding traditional use as a topical moisturizer for dry skin, attributed to its high palmitoleic acid and squalene content that mimic skin sebum. It helps repair the skin barrier and reduce trans-epidermal water loss. While mechanistically plausible, large controlled clinical trials specifically demonstrating efficacy for dry skin are limited.
Safflower oil is rich in linoleic acid (~75%), a key fatty acid for skin barrier function and moisture retention. Traditional and cosmetic use of safflower oil for dry skin is well-established; its lightweight texture facilitates skin absorption. Safflower seed extracts also contain skin-whitening and antioxidant compounds relevant to skin health.
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