Rosemary

Rosemary (Salvia rosmarinus / Rosmarinus officinalis): A Comprehensive Reference

1. Identity: Botanical Name, Source, and Taxonomy

Rosemary is botanically designated Rosmarinus officinalis Linn. or, under the revised classification accepted by modern taxonomy, Salvia rosmarinus Spenn. Now considered a species of Salvia, it is a member of the Lamiaceae family of mints and other herbs. The name "rosemary" comes from the Latin ros marinus, meaning "dew of the sea," referring to its ability to survive with only the moisture from sea air.

Rosemary is an evergreen bushy shrub which grows along the Mediterranean Sea and sub-Himalayan areas. Today, rosemary is grown worldwide but it is an evergreen perennial shrub native to southern Europe and Asia, especially the Mediterranean region. It is a small perennial shrub with fragrant evergreen needle-shaped leaves and white, pink, purple, or blue flowers.

Common Forms and Preparations

Rosemary is available in a variety of commercial and traditional preparation forms. According to the European Medicines Agency (EMA) herbal monograph, the recognized herbal substance is the whole or fragmented, dried leaf (comminuted herbal substance), prepared as herbal tea for oral use or as a bath additive. The essential oil is also a recognized herbal preparation, available in liquid or semi-solid dosage forms for oral use, cutaneous use, and/or use as a bath additive. Additional preparations reported in the literature include: dried leaf powder in capsule form, hydroalcoholic tinctures, standardized polyphenol extracts, and topically applied essential oil. Traditional uses include 2 g of chopped leaf infused in water, or 2 to 4 g of the shoot.

2. Traditional and Historical Use

The plant has been cultivated for thousands of years in the Mediterranean region, where it was valued for its culinary, medicinal, and symbolic properties. The Egyptians used rosemary in burial rituals, and traces have been found in tombs dating to 3000 BCE. In ancient Greece and Rome it was associated with memory and purification, often burned as incense, and thought to banish diseases and evil spirits. During the Middle Ages, rosemary was widely used in Europe to ward off illness and often burned in homes and hospitals for purification.

Ancient cultures recognized the herb's medicinal properties, using it to provide relief for a range of ailments including pain, inflammation, and indigestion. Physician Pedanius Dioscorides included rosemary in his most famous work, De Materia Medica, a first-century Greek encyclopedia on herbal medicine. In Greece and Rome, students wore crowns of rosemary during examinations to improve their memory.

Ibn Sina (980–1037), best known in the West as Avicenna, noted that rosemary is "beneficial for the brain" and described its dissolving properties. Ibn al-Baytar recommended it against amenorrhea, liver and spleen inflammation, pulmonary infections, cough, spasm, and dropsy, and particularly noted that rosemary flowers were indicated for problems affecting the head and brain due to cold and humidity, asserting they "increase senses acuity and memory, and reinforce the nervous system."

Rosemary has been traditionally used to treat memory-related disorders, hypertension, headache, insomnia, and diseases related to the respiratory system. It is considered a powerful cardiac stimulant, a strong antiseptic, antispasmodic, carminative, emmenagogue, and nervine tonic, and is used to cure arthritis, dandruff, and skin diseases.

In the Complete German Commission E Monographs, rosemary leaf is approved for internal use in dyspeptic complaints and for external use as supportive therapy in rheumatic diseases. According to the EMA, rosemary leaf preparations have traditional medicinal use for the symptomatic relief of dyspepsia and mild spasmodic disorders of the gastrointestinal tract and for the relief of minor muscular and articular pain and in minor peripheral circulatory disorders. Traditional medicinal use means that the use in the specified indication is exclusively based upon long-standing medicinal use and not based on results from clinical studies.

3. Key Chemical Constituents and Active Compounds

Phytochemical studies revealed that rosemary contains terpenoids, essential oils, alkaloids, and flavonoids. Chemical analysis of different kinds of rosemary extracts reveals that the most potent active components are triterpenes, phenolic diterpenes, and phenolic acids including rosmarinic acid, carnosic acid, rosmanol, carnosol, ursolic acid, and betulinic acid. Rosmarinic acid and carnosic acid possess the most medicinal effects among these phenolic compounds, particularly as anti-inflammatory and antioxidant agents.

UHPLC-ESI-QTOF-MS analysis has enabled the detection of more than 50 polyphenols, including phenolic acids, flavonoids, and terpenoids in various rosemary extracts. Analytical methods have yielded very high concentrations of rosmarinic acid (33,491 µg/g), carnosol (22,000 µg/g), carnosic acid (2,915 µg/g), and ursolic acid (5,144 µg/g) in certain extracts.

Essential Oil Constituents

The chemical composition of rosemary essential oils includes notable constituents such as 1,8-cineole (eucalyptol), α-pinene, camphor, linalool, and camphene, among others. The chemical profile varies with regionality, seasonality, environmental conditions, agronomic conditions, and the variety of rosemary. In most cases, α-pinene, eucalyptol, and camphor are major compounds in rosemary essential oil. Other compounds such as verbenone, borneol, and bornyl acetate have also been reported as principal compounds in the essential oil in certain chemotypes.

Mechanisms of Action of Key Constituents

Carnosic Acid and Carnosol

Carnosic acid (CA) and carnosol (CAR) are the two major diterpenes of rosemary. They possess a phenolic structural moiety and are endowed with the power to remove cellular reactive oxygen species (ROS) either through direct scavenging reaction or indirectly through upregulation of antioxidant defences. Their anti-inflammatory and therapeutic potential is orchestrated through modulating various signalling pathways of inflammation, including NF-κB, MAPK, Nrf2, SIRT1, STAT3, and NLRP3 inflammasomes, among others. Consequently, they ameliorate the expression of pro-inflammatory cytokines (e.g., TNF-α, IL-1, and IL-6), adhesion molecules, chemokines, and prostaglandins.

Rosemary leaves contain two phenolic diterpenes, carnosic acid and carnosol, which provide protection against oxidative stress by distinct mechanisms involving ROS scavenging or inhibition of lipid oxidation. Under oxidative conditions that do not involve ROS generation, carnosol inhibited lipid peroxidation, contrary to carnosic acid. Using spin probes and electron paramagnetic resonance detection, carnosic acid, rather than carnosol, was confirmed to be the primary ROS quencher.

Carnosic acid and carnosol are the main constituents with antioxidant properties and are responsible for approximately 90% of the properties. Both are inhibitors of lipid peroxidation in liposomal and microsomal systems, good scavengers of peroxyl radicals (CCl₃O₂), reduce cytochrome c, and scavenge hydroxyl radicals.

Rosmarinic Acid

Rosmarinic acid is a phenolic depside (an ester of caffeic acid and 3,4-dihydroxyphenyllactate) and is one of the principal polyphenolic compounds in rosemary. The main antioxidant compounds found in rosemary extract are rosmarinic acid, carnosic acid, and carnosol. Carnosic acid and carnosol are phenolic diterpenes of abietane type, and rosmarinic acid is an ester of caffeic acid and 3,4-dihydroxyphenyllactate. Rosmarinic acid was observed to have very scarce toxicity, with an LD₅₀ of 561 mg/kg in mice.

Anticholinesterase Activity (Cognitive Mechanisms)

The various mechanisms of rosemary and its constituents contributing towards cognition enhancement identified in preclinical studies include anticholinesterase, procholinergic, antioxidant, anti-amyloid, neuroprotective, and anti-inflammatory activity.

4. Scientific Evidence by Area of Use

4.1 Cognitive Function and Memory

Human/Clinical Evidence (Oral Administration):

A randomized, placebo-controlled, double-blinded, repeated-measures crossover study was conducted to investigate possible acute effects of dried rosemary leaf powder on cognitive performance. Twenty-eight older adults (mean age 75 years) were tested using the Cognitive Drug Research computerized assessment system 1, 2.5, 4, and 6 hours following a placebo and four different doses of rosemary. There was a biphasic dose-dependent effect in measures of speed of memory: the lowest dose (750 mg) had a statistically significant beneficial effect compared with placebo (P=.01), whereas the highest dose (6,000 mg) had a significant impairing effect (P<.01). There were also significant deleterious effects on other measures of cognitive performance at higher doses, although these were less consistent.

A separate study aimed to evaluate the effects of oral rosemary on memory performance, anxiety, depression, and sleep quality in university students. In this double-blinded randomized controlled trial, 68 participating students randomly received 500 mg rosemary or placebo twice daily for one month. The scores of all the scales and subscales except the sleep latency and sleep duration components of the Pittsburgh Sleep Quality Inventory were significantly improved in the rosemary group in comparison with the control group after one month. The authors concluded rosemary could be used to boost prospective and retrospective memory, reduce anxiety and depression, and improve sleep quality.

Human/Clinical Evidence (Aromatherapy/Inhalation):

A study was designed to assess the olfactory impact of rosemary essential oil on cognitive performance and mood in healthy volunteers. One hundred and forty-four participants were randomly assigned to one of three independent groups, and subsequently performed the Cognitive Drug Research computerized cognitive assessment battery in a cubicle containing either the rosemary odor, lavender odor, or no odor. Rosemary produced a significant enhancement of performance for overall quality of memory and secondary memory factors, but also produced an impairment of speed of memory compared to controls. These findings indicate that the olfactory properties of rosemary essential oil can produce objective effects on cognitive performance, as well as subjective effects on mood.

Preclinical (Animal) Evidence:

In animal studies, cognitive impairment was induced using various strategies including scopolamine, streptozotocin, amyloid-beta (Aβ), mild brain injury, and genetically modified aging models. The mechanisms of rosemary and its constituents contributing to cognition enhancement in these preclinical studies include anticholinesterase, procholinergic, antioxidant, anti-amyloid, neuroprotective, and anti-inflammatory activity.

Evidence strength: Human clinical evidence is limited to a small number of trials with modest sample sizes. Results are promising but preliminary; larger, longer-duration trials are needed before firm conclusions can be drawn.

4.2 Hair Growth (Androgenetic Alopecia)

A clinical study aimed to investigate the efficacy of rosemary oil in the treatment of androgenetic alopecia (AGA) and compare its effects with minoxidil 2%. Patients with AGA were randomly assigned to rosemary oil (n=50) or minoxidil 2% (n=50) for a period of 6 months. No significant change was observed in mean hair count at the 3-month endpoint in either group. In contrast, both groups experienced a significant increase in hair count at the 6-month endpoint compared with the baseline and 3-month endpoint (P<.05). No significant difference was found between the study groups regarding hair count at either month 3 or month 6. The frequency of scalp itching at the 3- and 6-month trial points was significantly higher in both groups compared with baseline; however, scalp itching was more frequent in the minoxidil group at both endpoints (P<.05).

Clinical studies show promising outcomes, but responses vary, and large-scale, long-term trials are lacking.

Evidence strength: One randomized comparative trial (n=100) supports non-inferiority of rosemary oil versus 2% minoxidil over 6 months, with a more favorable scalp tolerability profile. The comparison was made to 2% (not 5%) minoxidil. Evidence is preliminary; replication in larger trials is needed.

4.3 Antioxidant Activity

Rosemary has significant antimicrobial, anti-inflammatory, anti-oxidant, anti-apoptotic, anti-tumorigenic, antinociceptive, and neuroprotective properties. The antioxidant activity of rosemary is well-characterized in vitro and in preclinical models. Carnosic acid and carnosol are responsible for approximately 90% of the antioxidant properties; both are inhibitors of lipid peroxidation in liposomal and microsomal systems, good scavengers of peroxyl radicals, reduce cytochrome c, and scavenge hydroxyl radicals. Human clinical trials specifically assessing antioxidant biomarker changes are sparse; most evidence is from laboratory and animal models.

4.4 Anti-Inflammatory Effects

The anti-inflammatory mechanisms of rosemary's primary diterpenes are well-characterized at a molecular level. Carnosic acid and carnosol modulate various signalling pathways of inflammation, including NF-κB, MAPK, Nrf2, SIRT1, STAT3, and NLRP3 inflammasomes. Consequently, they ameliorate the expression of pro-inflammatory cytokines (e.g., TNF-α, IL-1, and IL-6), adhesion molecules, chemokines, and prostaglandins.

Evidence strength: Predominantly in vitro and animal evidence. Well-characterized mechanisms; human clinical trials targeting inflammatory endpoints are limited.

4.5 Antimicrobial Activity

The inhibitory effect of rosemary against microorganisms is the result of the action of rosmarinic acid, rosmaridiphenol, carnosol, epirosmanol, carnosic acid, rosmanol, and isorosmanol. These compounds interact with the cell membrane, causing changes in genetic material and nutrients, altering the transport of electrons, and causing leakage of cellular components. The essential oil from rosemary leaves is used as a natural antimicrobial, pesticide, and insect repellent.

Evidence strength: Evidence is primarily in vitro. Human clinical trials examining antimicrobial endpoints are not established in the literature reviewed.

4.6 Anticancer Properties

Rosemary extract has been shown to exhibit anticancer properties including inhibition of cancer cell proliferation and survival, and enhanced apoptotic activity in vitro and in vivo in colon, breast, prostate, and leukemic cancers, among others. The antitumor effect of rosemary has been related to diverse mechanisms, such as antioxidant effect, antiangiogenic properties, epigenetic actions, regulation of the immune response and anti-inflammatory response, modification of specific metabolic pathways, and increased expression of onco-suppressor genes.

A limited number of in vitro and in vivo animal studies provide evidence of anticancer effects of rosemary extract; however, human clinical data remain absent.

Evidence strength: Exclusively preclinical (in vitro and animal). No human clinical trials demonstrating anticancer efficacy have been identified. This area should be regarded as exploratory.

4.7 Antidiabetic / Blood Glucose Effects

Rosemary is an evergreen shrub containing various polyphenols. Rosemary extract and its polyphenolic constituents have been reported to have antioxidant, anti-inflammatory, anticancer, and anti-hyperglycemic properties. Existing in vitro and in vivo studies have examined the anti-diabetic effects of rosemary extract and its polyphenolic components. Beneficial effects have been reported with regard to lipid metabolism and plasma glucose levels. Previous studies found that rosemary extract caused a significant increase in glucose uptake and AMPK activation in skeletal muscle cells.

Evidence strength: Primarily in vitro and animal studies. Human clinical data are very limited, and no firm conclusions can be drawn for clinical application.

4.8 Gastrointestinal Effects (Dyspepsia, Antispasmodic)

The EMA recognizes rosemary leaf preparations for traditional medicinal use in the symptomatic relief of dyspepsia and mild spasmodic disorders of the gastrointestinal tract. The German Commission E monographs approve rosemary leaf for internal use in dyspeptic complaints. These approvals are based on traditional use, not formal clinical trial evidence.

4.9 Musculoskeletal and Circulatory Effects

Rosemary leaf preparations have traditional medicinal use for the relief of minor muscular and articular pain and in minor peripheral circulatory disorders according to the EMA. The German Commission E also approves rosemary for external use as supportive therapy in rheumatic diseases. These designations are also based on long-standing traditional use rather than controlled clinical trial data.

4.10 Mood, Anxiety, and Sleep

Rosemary shows important clinical effects on mood, learning, memory, pain, anxiety, and sleep. In the randomized trial of university students cited above, 500 mg twice daily for one month could be used to boost prospective and retrospective memory, reduce anxiety and depression, and improve sleep quality. These findings are promising but limited by the small scale of trials and the population studied (healthy university students).

5. Body Systems Associated with Rosemary

• Central Nervous System: Memory, cognition, mood, anxiety, neuroprotection
• Gastrointestinal System: Dyspepsia, antispasmodic, carminative
• Integumentary System (Skin and Hair): Hair growth, contact dermatitis (adverse), antimicrobial properties
• Musculoskeletal System: Minor muscular and articular pain
• Cardiovascular and Peripheral Circulation: Minor peripheral circulatory disorders
• Immune System: Anti-inflammatory, antioxidant, antimicrobial activities
• Endocrine/Metabolic: Exploratory antidiabetic and lipid-modulatory effects (preclinical)

6. Dosage Forms and Dosages Reported in Studies

Oral adult dosage reported in clinical reference sources includes 1–2 g of crude leaf per 150 mL water, ingested three times daily as tea. Traditional preparations described include 2 g of chopped leaf infused in water, or 2 to 4 g of the shoot.

The following dosages were specifically used in identified clinical and research studies:

• 500 mg rosemary (oral capsule) twice daily for one month was used in a double-blinded randomized controlled trial examining effects on memory, anxiety, depression, and sleep quality in university students.
• Twenty-eight older adults were tested following a placebo and four different doses of rosemary (including 750 mg and 6,000 mg as the lowest and highest tested doses in a crossover study on cognitive performance). The lowest dose (750 mg) had a statistically significant beneficial effect on speed of memory (P=.01), whereas the highest dose (6,000 mg) had a significant impairing effect (P<.01).
• In the androgenetic alopecia trial, patients were randomly assigned rosemary oil (n=50) or minoxidil 2% (n=50) for a period of 6 months as a topical scalp application.
• The EMA draft monograph lists recognized herbal preparations including comminuted herbal substance and hydroalcoholic extracts with specified extraction ratios (1:17.5–18.9 and 1:12.5–13.5) using liqueur wine as solvent.

7. Safety Considerations and Interactions

General Safety Status

Rosemary has been classified as "generally recognized as safe" (GRAS) by the FDA in America (CFR182.10; 182.20). The EMA has concluded that rosemary preparations are safe if used in recommended doses.

Acute Toxicity Data

The median lethal dose (LD₅₀) value of methanolic extract of rosemary leaves administered intraperitoneally to mice was 4.125 g/kg body weight. Rosmarinic acid was observed to have very scarce toxicity, with an LD₅₀ of 561 mg/kg in mice. The oral LD₅₀ of carnosic acid was 7,100 mg/kg in acute toxicity in mice.

Pregnancy and Lactation

Due to the lack of data, the EMA states that use of rosemary is not recommended during pregnancy and lactation, and use is contraindicated in hypersensitive patients. Rosemary may have emmenagogic and abortifacient effects. A comprehensive review of rosemary toxicity concluded that while rosemary is considered safe for food preservation, caution is warranted regarding chronic and high doses due to potential adverse effects on the kidneys, liver, reproductive system, and teratology.

Neurological Risk (Seizures)

Although case reports of seizures due to rosemary are lacking, the potential for toxicity exists, possibly due to the high camphor content found in rosemary oil. There is an increased risk of seizures with drugs that lower the seizure threshold.

High-Dose and Essential Oil Toxicity

Ingestion of large quantities of rosemary may cause stomach and intestinal irritation, kidney damage, and/or toxicity. Ingestion of undiluted essential oil can be toxic and cause significant adverse effects.

Drug Interactions

There is an increased risk of bleeding with antiplatelet agents or anticoagulants when rosemary is used concurrently. The EMA assessment report notes that results from experimental studies to support the proposed indications are very limited, and specific data on pharmacokinetics and interactions are not available.

Biliary and Hepatic Contraindications

Hot and full baths using rosemary preparations are contraindicated in cases of open wounds, large skin injuries, acute skin diseases, high fever, and severe infections. The EMA also notes that rosemary preparations should not be used in cases of obstruction of the bile duct, cholangitis, liver disease, gallstones, and any other biliary disorders.

Skin Sensitivity

Dermatitis, allergy, and photosensitivity to rosemary extracts or oil have been reported.

Gaps in Safety Data

The EMA notes that non-clinical information on the safety of rosemary leaf and essential oil is scarce. Tests on reproductive toxicity, genotoxicity, and carcinogenicity have not been performed. Further research is recommended to enhance understanding of the toxicity profile associated with rosemary.

References

• Habtemariam S et al. Therapeutic effects of rosemary (Rosmarinus officinalis L.) and its active constituents on nervous system disorders. PMC / NCBI, 2020.
• Nieto G et al. Antioxidant and Antimicrobial Properties of Rosemary (Rosmarinus officinalis, L.): A Review. PMC / NCBI, 2018.
• Borras-Linares I et al. Full-Spectrum Analysis of Bioactive Compounds in Rosemary as Influenced by Different Extraction Methods. PMC / NCBI, 2020.
• Begum S et al. Rosemary Essential Oils as a Promising Source of Bioactive Compounds: Chemical Composition, Thermal Properties, Biological Activity, and Gastronomical Perspectives. PMC / NCBI, 2021.
• Nematolahi P et al. Effects of Rosmarinus officinalis L. on memory performance, anxiety, depression, and sleep quality in university students: A randomized clinical trial. PubMed, 2018.
• Pengelly A et al. Short-term study on the effects of rosemary on cognitive function in an elderly population. PubMed / Journal of Medicinal Food, 2012.
• Moss M et al. Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults. PubMed, 2003.
• Pengelly A et al. Cognition enhancing effect of rosemary (Rosmarinus officinalis L.) in lab animal studies: a systematic review and meta-analysis. PMC / NCBI, 2022.
• Panahi Y et al. Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial. Medscape / SKINmed, 2015.
• Muñoz-González I et al. Anti-Inflammatory Therapeutic Mechanisms of Natural Products: Insight from Rosemary Diterpenes, Carnosic Acid and Carnosol. PMC / Biomedicines, 2023.
• Mène-Saffrané L et al. Carnosic Acid and Carnosol, Two Major Antioxidants of Rosemary, Act through Different Mechanisms. PMC / Plant Physiology, 2017.
• Moore J et al. Anticancer Effects of Rosemary (Rosmarinus officinalis L.) Extract and Rosemary Extract Polyphenols. PMC / NCBI, 2016.
• Charbel Khalil M et al. Anticancer Activity of Rosmarinus officinalis L.: Mechanisms of Action and Therapeutic Potentials. PMC / NCBI, 2020.
• Naimi M et al. Rosemary Extract as a Potential Anti-Hyperglycemic Agent: Current Evidence and Future Perspectives. PMC / NCBI, 2017.
• European Medicines Agency (EMA). Rosmarini folium – Herbal Medicinal Product Summary. EMA, 2024.
• European Medicines Agency (EMA). European Union Herbal Monograph on Rosmarinus officinalis L., folium. EMA/HMPC/513940/2021.
• European Medicines Agency (EMA). Final Assessment Report on Rosmarinus officinalis L., aetheroleum and folium. EMA.
• Davis's Drug Guide. Rosemary (Rosmarinus officinalis). Unbound Medicine.
• Naimi M et al. Toxicity and safety of rosemary (Rosmarinus officinalis): a comprehensive review. PubMed, 2024.
• Shouse B. Rosemary: The Herb of Ritual and Remembrance. JSTOR Daily, 2024.
• American Herbal Products Association. Herbs in History: Rosemary. AHPA.
• Britannica. Rosemary: Description, History, Plant, Herb, Spice, Uses, & Facts. Encyclopædia Britannica, 2024.
• Drugs.com. Rosemary Uses, Benefits & Dosage. Drugs.com, 2025.
• El-Hawary S et al. Rosmarinus officinalis L. as Fascinating Source of Potential Anticancer Agents Targeting Aromatase and COX-2: An Overview. PMC / NCBI, 2025.
• Oi Y et al. Rosmarinic Acid, a Rosemary Extract Polyphenol, Increases Skeletal Muscle Cell Glucose Uptake and Activates AMPK. PMC / NCBI, 2018.