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White Willow Bark

Salix alba
Evidence Level
Moderate
3 Clinical Trials
5 Documented Benefits
3/5 Evidence Score

White willow bark is the bark of Salix alba and related willow species, used for centuries as a traditional analgesic and the historical precursor to aspirin. It contains salicin and related salicylates that are metabolized in the body to salicylic acid, the same active metabolite as acetylsalicylic acid (aspirin), along with flavonoids and polyphenols that may contribute additional anti-inflammatory activity. Standardized willow bark extracts providing approximately 120-240 mg of salicin per day have been studied in randomized controlled trials for low back pain and osteoarthritis, with the higher dose producing greater pain relief than placebo. Because of its salicylate content, white willow bark shares the safety precautions of aspirin, including bleeding and Reye-syndrome risk.

Studied Dose 120-240 mg salicin per day, often divided. Not for use in children with viral illness.
Active Compound Salicin and other salicylates (salicortin, tremulacin), plus flavonoids and polyphenols; typically standardized to 120 or 240 mg salicin daily.

Benefits

Supports low back comfort

Standardized willow bark extracts providing 240 mg of salicin daily have been shown in randomized trials to support reductions in low back pain compared with placebo, with effects building over several weeks of consistent use.

Supported by Trial 1, Trial 2

May ease osteoarthritis-related discomfort

Randomized trials of standardized willow bark extract have shown moderate analgesic effects in adults with osteoarthritis, supporting its traditional use as a botanical aid for joint discomfort in selected adults.

Supported by Trial 3, Trial 2

Multi-component anti-inflammatory profile

Beyond salicin-derived salicylic acid, willow bark provides flavonoids and polyphenols that may contribute additional anti-inflammatory and antioxidant activity, supporting a broader pharmacological footprint than salicin alone.

Supported by Trial 1, Trial 2

Traditional botanical analgesic

Willow bark has centuries of traditional use as an analgesic and was the historical precursor to modern aspirin, providing a recognizable botanical option for adults exploring plant-derived approaches to occasional pain.

Supported by Trial 2, Trial 1

Once- to twice-daily standardized dosing

Standardized willow bark extracts allow consistent salicin delivery across the day with simple dosing schedules, supporting practical use over short courses of several weeks in adults with low back or joint discomfort.

Supported by Trial 3, Trial 1

Mechanism of action

1

Salicin to salicylic acid conversion

Gut bacteria hydrolyze salicin to saligenin, which is absorbed and oxidized in the liver to salicylic acid, the same active metabolite as that produced from acetylsalicylic acid (aspirin), responsible for much of the analgesic and anti-inflammatory effect.

2

Cyclooxygenase pathway modulation

Salicylic acid and willow bark constituents can inhibit cyclooxygenase enzymes and reduce prostaglandin synthesis in inflammatory cells, contributing to reductions in pain signaling and inflammatory mediator output.

3

Polyphenol and flavonoid activity

Willow bark flavonoids and polyphenols show antioxidant and anti-inflammatory activity in laboratory studies, which may contribute additional support beyond what is attributable to salicin alone.

4

Slower, more prolonged salicylate exposure

Salicin is gradually converted to salicylic acid via gut and hepatic metabolism, producing lower peak but more prolonged salicylate levels than equivalent doses of acetylsalicylic acid, which may influence its analgesic profile and tolerability.

Clinical trials

1
Willow bark RCT in low back pain

Randomized, double-blind, placebo-controlled trial; 4 weeks; willow bark extract providing 120 or 240 mg salicin daily vs placebo.

210 adults with low back pain exacerbations.

The 240 mg salicin group showed significantly higher rates of pain-free status without rescue medication than placebo, with intermediate benefit at 120 mg, supporting a dose-response effect of standardized willow bark on acute low back pain.

2
Willow bark RCT in osteoarthritis

Randomized, double-blind, placebo-controlled trial; 2 weeks; standardized willow bark extract providing 240 mg salicin daily.

78 adults with osteoarthritis of hip or knee.

Willow bark extract produced a moderate analgesic effect in osteoarthritis pain compared with placebo, with generally good tolerability over the 2-week intervention period.

3
Systematic review of willow bark for musculoskeletal pain

Systematic review of randomized clinical trials of Salix-based preparations across musculoskeletal pain conditions.

Adults with low back pain, osteoarthritis, or other musculoskeletal pain syndromes.

Reviewers concluded there is moderate evidence supporting ethanolic willow bark extract for low back pain, mixed evidence for osteoarthritis, and insufficient data for rheumatoid arthritis, with overall safety comparable to short courses of conventional analgesics in adults.

Side effects and drug interactions

Common Potential side effects

Stomach upset, heartburn, or dyspepsia, especially when taken without food.
Increased risk of gastrointestinal bleeding similar to aspirin and other salicylates.
Allergic reactions in people with aspirin or salicylate sensitivity, which can be severe.
Reye syndrome risk: must not be given to children or teens with viral illness.
Asthma exacerbation in salicylate-sensitive individuals.

Important Drug interactions

Adds bleeding risk with warfarin, DOACs, heparin, and other anticoagulants.
Adds bleeding risk with antiplatelet drugs such as aspirin, clopidogrel, or NSAIDs.
May reduce effects or worsen GI risk when combined with corticosteroids.
May affect kidney function and lithium clearance when combined with diuretics or lithium.

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Frequently asked questions about White Willow Bark

What is white willow bark used for?

White willow bark is a traditional herb containing salicin, a natural compound the body converts to a substance similar to aspirin. It is used for pain, headaches, and joint and muscle discomfort, and is sometimes called nature's aspirin.

Does white willow bark work like aspirin?

Yes, in a gentler, slower way: its salicin is converted to salicylic acid (related to aspirin), which is the basis for its use in easing pain and inflammation. The effect is milder and slower than aspirin but longer-lasting for some.

How much white willow bark should I take?

Studies use extracts standardized to salicin, often providing about 120 to 240 mg of salicin per day; follow product labeling. Give it time, as it acts more gradually than aspirin.

Is white willow bark safe?

Because it acts like aspirin, it carries similar cautions: avoid it if you are allergic to aspirin or salicylates, have ulcers or bleeding risk, or take blood thinners, and do not give it to children or teens with viral illness (Reye's syndrome risk). Pregnant women should avoid it; check with a doctor.

What is White Willow Bark?

White willow bark is the bark of Salix alba and related willow species, used for centuries as a traditional analgesic and the historical precursor to aspirin. It contains salicin and related salicylates that are metabolized in the body to salicylic acid, the same active metabolite as acetylsalicylic acid (aspirin), alo…

What is the recommended dosage of White Willow Bark?

The clinically studied dose is 120-240 mg salicin per day, often divided. Not for use in children with viral illness. Always follow the product label and check with a healthcare provider for personal advice.

Is White Willow Bark safe, and does it have side effects?

For most healthy adults, White Willow Bark is well tolerated at studied doses. Reported effects can include: Stomach upset, heartburn, or dyspepsia, especially when taken without food. Increased risk of gastrointestinal bleeding similar to aspirin and other salicylates. It may also interact with some medications. White Willow Bark is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does White Willow Bark interact with any medications?

Possible interactions include: Adds bleeding risk with warfarin, DOACs, heparin, and other anticoagulants. Adds bleeding risk with antiplatelet drugs such as aspirin, clopidogrel, or NSAIDs. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for White Willow Bark?

NutraSmarts rates the evidence for White Willow Bark as Moderate (3 out of 5). It is backed by 3 clinical trials and 5 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(5 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Chrubasik S, Eisenberg E, Balan E, Weinberger T, Luzzati R, Conradt C. Treatment of low back pain exacerbations with willow bark extract: a randomized double-blind study. American Journal of Medicine. 2000;109(1):9-14.PubMedUsed to support: RCT in 210 adults with low back pain exacerbations: 240 mg salicin/day produced significantly higher rates of pain-free response vs placebo, supporting a dose-response analgesic effect.
  2. Schmid B, Lüdtke R, Selbmann HK, Kötter I, Tschirdewahn B, Schaffner W, Heide L. Efficacy and tolerability of a standardized willow bark extract in patients with osteoarthritis: randomized placebo-controlled, double blind clinical trial. Phytotherapy Research. 2001;15(4):344-50.PubMedUsed to support: 2-week RCT in 78 adults with hip/knee osteoarthritis: willow bark extract providing 240 mg salicin produced a moderate analgesic effect vs placebo with good tolerability.
  3. Vlachojannis JE, Cameron M, Chrubasik S. A systematic review on the effectiveness of willow bark for musculoskeletal pain. Phytotherapy Research. 2009;23(7):897-900.PubMedUsed to support: Systematic review concluded moderate evidence supports ethanolic willow bark extract for low back pain, with mixed/insufficient evidence for osteoarthritis and rheumatoid arthritis.
  4. Schmid B, Kötter I, Heide L. Pharmacokinetics of salicin after oral administration of a standardised willow bark extract. European Journal of Clinical Pharmacology. 2001;57(5):387-91.PubMedUsed to support: Pharmacokinetic study: salicin from standardized willow bark extract is converted in vivo to salicylic acid (the active metabolite of aspirin), confirming the salicylate-based mechanism.
  5. Clauson KA, Santamarina ML, Buettner CM, Cauffield JS. Evaluation of presence of aspirin-related warnings with willow bark. Annals of Pharmacotherapy. 2005;39(7-8):1234-7.PubMedUsed to support: Survey of 70 willow bark products found only 8.6% included aspirin-related safety warnings, underscoring the need to disclose salicylate-related risks (bleeding, Reye syndrome, salicylate allergy) for willow bark users.