White Willow

White willow bark's primary active compound is salicin, a glycoside that is absorbed in the small intestine and then progressively converted into salicylic acid, the same active form created when the body metabolizes aspirin. Salicylic acid inhibits cyclooxygenase (COX) enzymes, reducing production of prostaglandins that mediate pain, inflammation, and fever. However, the conversion of salicin to salicylic acid is slower and produces lower peak blood levels than aspirin, which is rapidly hydrolyzed in the bloodstream. The slower onset and lower peak levels may explain why white willow bark generally causes less gastric irritation than aspirin, but it also means slower and milder analgesic effects. White willow bark also contains other compounds including polyphenols and flavonoids that may contribute to additional anti-inflammatory and antioxidant effects. The combination may produce broader effects than isolated salicin, though the relative contribution of these compounds is not fully characterized. Clinical evidence is most developed for low back pain and osteoarthritis.

There is no established RDA. Standardized extracts are typically dosed to provide 120 to 240 mg of salicin per day. This usually translates to 240 to 480 mg of standardized extract (at typically 15 percent salicin) once or twice daily. Clinical trials for back pain have used products providing 120 to 240 mg of salicin per day. Effects typically emerge over days to weeks for chronic pain conditions.

Take white willow bark with food to reduce gastrointestinal effects. Doses are typically divided once or twice daily, depending on the product. For chronic pain conditions like back pain or osteoarthritis, effects often emerge over days to weeks. For acute pain, onset is slower than aspirin (often 1 to 2 hours rather than 30 minutes).

White willow bark is generally tolerated at typical doses. Side effects include gastrointestinal upset (less common than with aspirin but possible), nausea, and skin rashes. Allergic reactions can occur, particularly in people with aspirin or NSAID allergy. Rare cases of more serious reactions have been reported. At high doses, similar effects to aspirin overdose are theoretically possible (tinnitus, hyperventilation). There is no established Tolerable Upper Intake Level.

White willow bark shares aspirin's interaction profile. It may potentiate effects of anticoagulants (warfarin, heparin, dabigatran), antiplatelet drugs, and NSAIDs, increasing bleeding risk. May reduce effectiveness of beta-blockers and ACE inhibitors. May increase methotrexate toxicity. Use with diabetes medications may enhance hypoglycemic effects. Potential interaction with valproic acid.