IngredientsGolden Willow is the common name applied to Salix alba var. vitellina (L.) Stokes, sometimes rendered as the cultivar Salix alba 'Vitellina'. It is a cultivar of white willow grown for its shoots, which are golden-yellow for one to two years before turning brown. It belongs to the genus Salix, family Salicaceae. It has been cultivated since Roman times. The cultivar epithet vitellina is derived from the Latin vitellus, meaning "yolk of egg," referring to the colour of the tree's newly formed stems.
In medicinal and dietary-supplement contexts, Golden Willow is not a sharply distinct pharmacognostic entity separate from white willow (Salix alba L.) or other closely related willows. The herbal drug known commercially as "willow bark" (Latin: Salicis cortex) is derived from several Salix species. While white willow (Salix alba) is the willow species most commonly used for medicinal purposes, crack willow (Salix fragilis), purple willow (Salix purpurea), and violet willow (Salix daphnoides) are all salicin-rich species and are available under the label of willow bark. The PFAF Plant Database and multiple herbal references use "Golden Willow" and white willow interchangeably in the medicinal context. Its common names reflect its utility and beauty: Cricket Bat Willow nods to its strong, pliable wood, while Golden Willow evokes its shimmering foliage.
Golden Willow (Salix alba vitellina) is a deciduous tree growing to 20 m (65 ft) by 10 m (32 ft) at a fast rate. Its narrow lanceolate leaves are pale green in colour, have a covering of fine hairs more prominent on the underside, and are up to 10 cm long. The branches ascend from the trunk. The trunk may achieve a diameter of 1 m, and the bark is deeply fissured and grayish-brown in colour. The year-old branches are bright yellow or orange, dulling with age. The species is dioecious — individual flowers are either male or female, but only one sex is found on any one plant. Var. vitellina, commonly called golden willow, produces new stems that are bright golden yellow in colour, especially noticeable in winter. Golden willow is often grown not as a tree but as a multi-stemmed shrub with the branches being cut back heavily each year in late winter.
Var. vitellina is rather a group of clones than a proper botanical variety. Salix alba, commonly called white willow, is native to Europe, central Asia, and northern Africa. It was brought to the U.S. in the 1700s by European settlers and has since escaped and naturalized in many parts of North America.
The genus Salix as a whole contains more than 330–500 species and 200 hybrids, and its trees, shrubs, or prostrate plants are widely distributed in Africa, North America, Europe, and Asia.
The medicinal part is the bark. By definition, the herbal drug consists of the whole or fragmented dried bark of young branches or whole dried pieces of current-year twigs of various species of the genus Salix. The bark from young branches and twigs, harvested in spring when the sap is rising, is considered the most medicinally potent. Leaves have also been studied for their polyphenolic content; the phytochemical profile of white willow leaf extract had not been investigated in detail until recently.
Willow bark is available as a supplement in various forms, including capsules, which can be purchased from many drugstores and almost any health food store. Willow bark can also be used topically as an ingredient in creams or other skin care products. Historically, willow was employed in a variety of preparations: it was brewed as a tea, chewed, or used in poultices to address headaches, back pain, inflammation, and joint discomfort. In standardized supplement form, willow bark is commonly offered as a dry extract characterized by its total salicin content. The EMA monograph describes a dry extract (8–14:1), with extraction solvent ethanol 70% V/V, standardized to 15% total salicin.
Comminuted or powdered barks from Salix species have a history of ethno-medical use stretching back to ancient Greek, Assyrian, and Egyptian civilisations. Ancient Egyptians used willow bark for pain and inflammation, as recorded in the Ebers Papyrus (circa 1550 BCE), and Hippocrates prescribed it for fevers. The ancient Sumerians and Egyptians, as well as Hippocrates, Celsus, Pliny the Elder, Dioscorides, and Galen used these natural products as remedies for pain, fever, and inflammation.
In the Middle Ages, these remedies were used for fever and rheumatism by Hildegard of Bingen and Henrik Harpestreng. Willow bark preparations remained a cornerstone of European herbal medicine throughout the medieval period, and the tradition carried into early modern times.
The first "clinical trial" was reported by Edward Stone in 1763, with a successful treatment of malarial fever with willow bark. In 1876, the antirheumatic effect of salicin was described by T. MacLagan, and that of salicylic acid by S. Stricker and L. Riess.
Native American tribes, such as the Cherokee, chewed the bark for headaches and applied it to wounds, while colonial herbalists used it for "ague" (malaria). Historically, Native Americans chewed willow bark to relieve pain.
In the mid-19th century, the active ingredient of willow bark, salicylic acid, was isolated and subsequently synthesized from phenol. It gained widespread use in compounded pharmaceuticals as a pain reliever, anti-inflammatory, and antipyretic. In the latter portion of the 19th century, the Bayer company in Germany developed a salicylic acid derivative, aspirin (or acetylsalicylic acid), for commercial use. Acetylsalicylic acid was synthesized by Charles Gerhardt in 1853 and in 1897 by Felix Hoffmann in the Bayer Company.
Across cultures, the bark's traditional applications were consistent. The bark is anodyne, anti-inflammatory, antiperiodic, antiseptic, astringent, diaphoretic, diuretic, febrifuge, hypnotic, sedative, and tonic. It has been used internally in the treatment of dyspepsia connected with debility of the digestive organs, rheumatism, arthritis, gout, inflammatory stages of auto-immune diseases, feverish illnesses, neuralgia, and headache. Its tonic and astringent properties rendered it useful in convalescence from acute diseases, in treating worms, chronic dysentery, and diarrhoea.
Salicylate derivatives are the primary medicinal constituents of willow bark. While small amounts of salicylic acid can be detected in most species, the principal salicylates of S. alba are the phenolic ester glycoside salicortin and the glycoside salicin, its acid hydrolysis product. Salicin is the precursor of salicylic acid, comprising about 1% of the white willow bark extract, whereas other glycosides comprise about 12%.
Studies with the main characteristic constituents salicin, salicortin, acetyl-salicortin, and tremulacin are included in the ESCOP monograph. The European Pharmacopoeia monograph on Salicis cortex requires a minimum of 1.5% total salicin in the dried drug.
Altogether, 322 secondary metabolites have been characterized in the genus, including flavonoids (94 compounds comprising flavonols, flavones, flavanones, isoflavones, flavan-3-ols such as catechins and procyanidins, chalcones, dihydrochalcones, anthocyanins, and dihydroflavonols), phenolic glycosides (76), organic acids (28), non-phenolic glycosides (17), sterols and terpenes (17), simple phenolics (13), and lignans (7), in addition to volatiles and fatty acids (69).
Aqueous and ethanolic willow bark extracts have been analyzed for total phenolics, phenolic acids, flavonoids, and tannins; the highest phenolic, tannin, and flavonoid contents are found in extracts obtained via microwave-assisted extraction using ethanol as a solvent.
Recent metabolomics screening has uncovered additional compounds of potential pharmacological significance. During a metabolomics screen of 86 Salix species in the UK National Willow Collection, researchers discovered, isolated, and fully characterised a new natural salicinoid — salicin-7-sulfate. This molecule may have important human pharmacological actions that need to be considered in determining the efficacy and safety of willow herbal medicines.
Researchers also described the isolation, structure determination, and anti-cancer activity of a cyclodimeric salicinoid called miyabeacin, from S. miyabeana and S. dasyclados. Additionally, a lignan derivative, sisymbrifolin, has been isolated from the bark of S. alba.
The salicylate content in willow species like S. alba and S. purpurea ranges from 1.5% to 15%. Among them, S. daphnoides and S. purpurea yield the highest concentrations of salicylates.
The key active component, salicin, is metabolized in the body to produce salicylic acid, which inspired the development of modern aspirin. Pharmacokinetic studies have characterized this conversion precisely. Salicylic acid is the major metabolite of salicin detected in the serum (86% of total salicylates), besides salicyluric acid (10%) and gentisic acid (4%). Peak levels are reached within less than 2 hours after oral administration. Renal elimination occurs predominantly in the form of salicyluric acid.
However, the salicylate concentrations generated from standard supplement doses are substantially lower than those from pharmaceutical aspirin. Peak serum levels of salicylic acid averaged 1.2 mg/L, and the observed area under the serum concentration-time curve of salicylic acid was equivalent to that expected from an intake of 87 mg acetylsalicylic acid. Willow bark extract at current therapeutic doses leads to much lower serum salicylate levels than observed after analgesic doses of synthetic salicylates, meaning the formation of salicylic acid alone is unlikely to explain analgesic or anti-rheumatic effects of willow bark.
The efficacy of willow bark extract in the treatment of painful mobility disorders has been attributed to salicin and its derivatives as pro-drugs of salicylates. However, based on clinical experience and experimental pharmacological studies, the fraction of total salicin cannot satisfactorily explain the clinical efficacy of willow bark. In addition, salicins and their metabolites lack the acetylating potential of acetylsalicylic acid (ASA) and must therefore possess a different mechanism of action. A detailed pharmacological screening of the aqueous willow bark extract STW 33-I found that all in vivo and in vitro models studied pointed to relevant contributions of the polyphenol and flavonoid fraction.
Flavonoids and polyphenols contribute to the potent willow bark analgesic and anti-inflammatory effect. The multi-component active principle of willow bark provides a broader mechanism of action than aspirin and is devoid of serious adverse events. In contrast to synthetic aspirin, willow bark does not damage the gastrointestinal mucosa.
Preclinical (non-human) research has explored additional mechanisms. Salicin suppressed the angiogenic activity of endothelial cells, such as migration, tube formation, and sprouting from an aorta. Salicin reduced reactive oxygen species (ROS) production and activation of the extracellular signal-regulated kinase (ERK) pathway. The expression of vascular endothelial growth factor (VEGF) was also decreased by salicin in endothelial cells, and when salicin was administered to mice, it inhibited tumor growth and angiogenesis in a mouse tumor model. These findings are from preclinical models and have not been validated in human trials.
In vitro experiments with willow bark extract or salicin have demonstrated anti-inflammatory, anti-angiogenesis, apoptotic, and cytotoxic activities, as well as metabolic transformations by kidney, liver, and lung. In vivo and ex vivo experiments in animals demonstrated anti-inflammatory, antipyretic, and anti-tumour effects. These animal and laboratory data require further human investigation before clinical conclusions can be drawn.
Low back pain is the most extensively studied indication for willow bark extract and the one for which the strongest regulatory acknowledgment exists. The EMA's Committee on Herbal Medicinal Products (HMPC) concluded that willow bark prepared as a dry extract can be used for the short-term treatment of lower back pain.
The key human trial was a randomized double-blind study. A daily dose of 1,572 mg willow bark extract of a proprietary preparation (Assalix; standardized to 15.2% salicin, i.e., 240 mg salicin per day) was significantly superior to placebo in patients with osteoarthritis of the hip and knee and in patients with exacerbations of chronic low back pain. In two open studies against active treatments, willow bark extract showed advantages over a routinely prescribed treatment scheme of orthopedic specialists based on nonsteroidal antirheumatic drugs and exhibited rather similar efficacy to the COX-2 inhibitor rofecoxib.
A systematic review confirmed the direction of evidence. Seven manuscripts were identified, reporting four trials with confirmatory and four with exploratory study designs. One confirmatory and two exploratory studies indicate a dose-dependent analgesic effect not inferior to rofecoxib in patients with low back pain. In one exploratory and one confirmatory study, conflicting results were achieved in participants with osteoarthritis.
Despite its long history of use, only a few small clinical trials have been conducted that support the use of willow bark extracts in chronic low-back pain and osteoarthritis. A 2019 review evaluated research on dietary ingredients for chronic musculoskeletal pain for Special Operations Forces personnel in the U.S. military. Nineteen eligible dietary ingredients were assessed for quality, efficacy, and safety, and recommendations were made against the use of willow bark extract and several other supplements to mitigate chronic musculoskeletal pain. This underscores that the evidence base, while directionally positive, remains modest in size and methodological robustness.
A study assessed the clinical efficacy of a chemically standardized willow bark extract in the treatment of osteoarthritis. Willow bark extract, at a dose corresponding to 240 mg salicin/day, was compared with placebo in a 2-week, double-blind, randomized controlled trial. The primary outcome measure was the pain dimension of the WOMAC Osteoarthritis Index; secondary outcomes included stiffness, physical function dimensions of the WOMAC, daily VAS pain and function scores, and final overall assessments. A total of 78 patients (39 willow bark extract, 39 placebo) participated. A statistically significant difference (d = 6.5 mm, 95% CI = 0.2–12.7 mm, p = 0.047) was observed; the WOMAC pain score was reduced by 14% from baseline after 2 weeks of active treatment, compared with an increase of 2% in the placebo group. The patient diary VAS confirmed this result, and the final overall assessments showed superiority of the willow bark extract over placebo. It was concluded that willow bark extract showed a moderate analgesic effect in osteoarthritis and appeared to be well tolerated.
A 2023 meta-analysis incorporating six randomized controlled trials (329 patients with arthritis) reached a similar conclusion. The results showed significant differences in pain relief and improvement in physical status for patients with arthritis between willow bark treatment and placebo groups, and no significant differences in the risk of all adverse events. Owing to potential bias, the certainty of evidence was still considered inadequate, and further RCTs were deemed necessary to confirm the results.
A 2023 research review looking at 329 patients with different types of arthritis found that people who used willow bark had more symptom relief than those who took a placebo. But in older research examining willow bark extract's effects on people with osteoarthritis and rheumatoid arthritis, inconclusive results were found. Some studies found no difference in pain relief compared to placebo or medication, while others showed minor improvements that did not reach statistical significance.
Willow bark is recognized by regulatory bodies for this traditional indication. The ESCOP monograph lists the therapeutic indications as low-back pain, mild rheumatic conditions, fever associated with common cold, and headache. Clinical trial evidence for the antipyretic use is largely derived from animal studies and historical precedent rather than modern randomized controlled trials in humans. Regulatory bodies such as the EMA have accepted this indication under traditional use criteria rather than well-established medicinal use. In six randomized-controlled and seven open clinical studies using orally administered willow bark extract in human patients with either low-back pain or various rheumatic conditions, relief of these conditions could be demonstrated.
Willow bark extract is commonly employed as a complementary therapy for pain and inflammation management, such as those related to low back pain, osteoarthritis, tendinitis, bursitis, and headaches. The evidence base for headache specifically is drawn largely from traditional use and the established mechanism of salicylate metabolism, rather than from dedicated headache-specific clinical trials.
Research on the potential anti-cancer properties of willow-derived compounds is at an early, preclinical stage. Researchers described the isolation, structure determination, and anti-cancer activity of a cyclodimeric salicinoid (miyabeacin) from S. miyabeana and S. dasyclados. Miyabeacin was found to be effective against several breast, throat, and ovarian cancer cell lines in laboratory tests. Both salicin and aspirin have been investigated for the prevention of cancer. The next steps identified by researchers are to scale up production of miyabeacin from farmed willow and provide more material for further medical testing. These findings are entirely preclinical and cannot be used to make any inference about efficacy in humans.
Willow bark extract has demonstrated antibacterial activity against Gram-positive bacteria S. aureus and P. aeruginosa in laboratory settings. No human clinical trials have evaluated willow bark as an antimicrobial agent, and this remains an in-vitro observation only.
Willows have also been shown in preclinical research to exert analgesic, anti-inflammatory, antioxidant, anticancer, cytotoxic, antidiabetic, antimicrobial, antiobesity, neuroprotective, and hepatoprotective activities. The evidence for the majority of these activities rests on cell culture and animal studies; human clinical corroboration is currently lacking.
Clinical research and official monographs consistently express dosing in terms of total salicin equivalents rather than raw bark weight, because salicin content varies markedly across preparations.
The most common adverse effects associated with willow bark are gastrointestinal; a few allergic reactions were also reported. Occasional, mild adverse events have been reported. Studies supported the hypothesis that willow bark extract is less prone to cause adverse reactions in the stomach compared to acetylsalicylic acid.
Under pharmacologically active doses, no adverse effects regarding the stomach mucosa were observed, in contrast to acetylsalicylic acid.
There is a risk of increased bleeding in vulnerable individuals, salicylates cross the placenta and are eliminated slowly in newborns, some persons are sensitive or allergic to aspirin, and children are at risk of Reye syndrome. In patients with known aspirin allergy, willow bark products are contraindicated.
Metabolism of 240 mg salicin from willow bark could yield 113 mg of salicylic acid, yet dietary supplement products are not required to be labeled with warnings. In contrast, over-the-counter low-dose aspirin (81 mg strength), which delivers 62 mg salicylic acid, is required by law to include cautions, warnings, and contraindications related to its use in pregnant and nursing women, children, and other vulnerable subpopulations, e.g., those using anticoagulants.
The United States Pharmacopeia has included a cautionary labeling statement in the USP Salix Species monograph: "Dosage forms prepared with this article should bear the following statement: 'Not for use in children, women who are pregnant or nursing, or by persons with known sensitivity to aspirin.'" All safety studies have involved adults only; none involved special subpopulations such as pregnant or breastfeeding women, or children.
Because willow bark could accumulate heavy metals, and there is no way to know how much has accumulated in the extract being used, this issue warrants awareness when sourcing supplements.
Willow bark extract displays an activity regarding thrombocyte (platelet) function, but the activity is clearly weaker than aspirin. An extract dose with 240 mg salicin had no major impact on blood clotting. Nonetheless, the interaction potential with anticoagulant drugs requires attention in clinical settings.
Golden Willow / willow bark holds recognized status in several major regulatory and pharmacopoeial frameworks:
Health conditions that Golden willow may help support.
Body systems that Golden willow may help support.
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