Side Effects of White Willow Bark

White willow bark has been used for thousands of years by herbalists for a variety of illnesses. The white willow is a deciduous tree, native to Europe, Asia and parts of North America. Its bark contains salicin which is similar to aspirin (acetylsalicylic acid). It is widely available in health food stores and online as an extract or in capsule form.

History

• Since the time of Hippocrates (more than 2,400 years ago), patients throughout China and Europe have been consuming white willow bark and drinking white willow bark tea to relieve aches and pains. The first-century Greek physician Dioscorides prepared white willow bark remedies. It was also used medicinally by Native Americans.

Medicinal Uses

• Herbalists use white willow bark to reduce the pain and inflammation of osteoarthritis, lower back syndromes, headache, tendinitis and bursitis. It may also be effective in reducing menstrual cramps and fever. White willow bark has not been approved by the U.S. Food and Drug Administration.

Side Effects

• Although thought by herbalists to be safer than aspirin, the U.S. Food and Drug Administration indicates that white willow bark should carry the same voluminous side effects as aspirin. These include gastric irritation, ulcers, headache, stroke, dizziness, tinnitus, confusion, visual difficulties, drowsiness, sweating, nausea, vomiting, hyperventilation and central nervous system disturbances, especially in high doses. Allergic reactions such as itching or broncho-spasm and swelling may also occur. Any side effects should be reported to a physician immediately.

People Who Should Not Take White Willow Bark

• Children with the flu or chickenpox should not be given white willow bark due to the risk of developing Reye syndrome which can cause severe injury to the liver. Women who are pregnant or breastfeeding should not take white willow bark. Patients with known allergic reactions to aspirin should not take white willow bark. Patients taking medication for hypertriglyceridemia or blood pressure abnormalities should consult a physician before taking white willow bark.

Drug and Supplement Interactions

• White willow bark may interact with several medications. Avoid taking white willow bark with acetazolamide, salicylates, carbonic anhydrase inhibitors, anticoagulants (warfarin or heparin), anti-platelet drugs (clopidogrel), non-steroidal anti-inflammatory medications (ibuprofen, naproxen), sulfinpyrazone, beta blockers, diuretics, phenytoin (Dilantin), probenecid, spironolactone, sulfonylureas or valproic acid. White willow bark also should not be used in conjunction with several herbs and supplements, including black cohosh, saw palmetto, ginkgo biloba, garlic, guaiacum resin, sarsaparilla, poplar bark or herbs and supplements containing tannins.

Scientific Study

• In Germany in 2001, a 2-week, double-blind, randomized controlled trial was performed to assess white willow bark extract's efficacy as a treatment of osteoarthritis. The study concluded that "the willow bark extract showed a moderate analgesic effect in osteoarthritis and appeared to be well tolerated." (See Resources.)

Other Names

• There are many other names for white willow bark, such as salix alba, purple willow, crack willow and European willow.