Willow (Salix spp.) is a source of salicin, which is metabolized to salicylic acid in the body. Salicin and salicylic acid are chemical precursors to aspirin (N-acetyl salicylic acid), a popular analgesic and antiinflammatory agent. However, the side effects of salicylic acid (unpleasant taste and gastric upset) precluded its widespread use. Aspirin, the acetylated version of salicylic acid, is better tolerated. In the United States, willow bark is used by herbalists as an antipyretic (fever reducer), a mild analgesic (pain reliever), and an anti-inflammatory. There is currently strong scientific evidence that willow bark is effective for osteoarthritis and lower back pain. Early study suggests that willow bark extracts may not be helpful for rheumatoid arthritis, but further study is warranted to confirm these recommendations, Taking willow bark may increase the risk of bleeding; however, this risk may be less than taking aspirin.
The values of willow lie in the glycosides salicin and populin as well as the tannin. The uses are many, but most specifically in the reduction of inflammations of joints and membranes. Useful for headache (caused by dampness and heat in the gastrointestinal tract), recurring fevers, gonorrhea, ovarian pains, dyspepsia, dysentery, chronic diarrhea, neuralgia, rheumatic aches and pains, worms, edema and hay fever. 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 render it useful in convalescence from acute diseases, in treating worms, chronic dysentery and diarrhea.
The fresh bark is very bitter and astringent. The salicin in it probably decomposes into salicylic acid in the human body. This is used as an anodyne and febrifuge. The glycosides are excreted in the urine as salicylic acid, salicyl alcohol, and related compounds; this renders the tea useful for urethra and bladder irritability, acting as an analgesic to those tissues. Most of our plants are not particularly potent and a fair amount of the bark or stem is needed. Up to an ounce a day can be consumed in tea if needed, but take no more than is needed for the problem.
Willow bark is a strong but benign antiseptic, and a good poultice or strong wash is made of the fresh or dried herb. For infected wounds, ulcerations, or eczema, the plant should be boiled in twice its volume of water in a covered pot for at least half an hour, some borax or boric acid added (tablespoon to a pint of water), and the tea used externally as often as necessary. It also may be taken as a bitter tonic in small doses before meals, to hasten convalescence from acute disease. The leaves are used internally in the treatment of minor feverish illnesses and colic. An infusion of the leaves has a calming effect and is helpful in the treatment of nervous insomnia. When added to the bath water, the infusion is of real benefit in relieving widespread rheumatism.(1)
Anti-inflammatory, analgesic, antipyretic, astringent. Salicin and related glycosides, in the intestinal tract liberate salicyl alcohol, which is oxidized in the liver into salicylic acid. As with aspirin, salicylic acid is the active compound, which accounts for the NSAID-like effect (anti-inflammatory, analgesic, antipyretic) by inhibiting the biosynthesis of inflammatory prostaglandins.
Salicin lacks the acetyl residue of aspirin, which binds to thromboxane synthetase of platelets, so it doesn't influence the biosynthesis of thrombocytes (= platelets). Due to tannins it also exerts astringent effect. (4)
glycosides salicine (salicoside) picein, triandrin and saoicortine; esters of salicylic acid and salicyl alcohol, acetylated salicin, salicortin and salireposide, and tannins (catchin, p-coumaric acid); flavonoids.
Overdoses of willow bark may cause skin rash, stomach inflammation/irritation, nausea, vomiting, kidney inflammation, and tinnitus (ringing in the ears).
Salicylates are not recommended during pregnancy, so pregnant and breastfeeding women should not take willow bark.
Like aspirin, willow bark is a proven painkiller, but without many of aspirin's side effects. The analgesic actions of willow are typically slower acting but last longer than standard aspirin products. As with aspirin, uses for willow bark include fever, colds, minor infections, acute and chronic rheumatic disorders, mild headaches, and pain caused by inflammation. Willow bark is also high in tannins, suggesting that it may be of some use in gastrointestinal disorders. Benefits of willow bark for specific health conditions include the following:
• Headache, migraine, osteoarthritis, and toothache. Aspirin has an advantage over its herbal parent in that it is more sure-acting, as willow bark depends on the presence of "friendly" intestinal bacteria to properly digest its components into painkilling compounds. On the other hand, the analgesic compounds from willow bark remain in circulation longer than those from aspirin. The amount of pain relieving compounds available from willow bark remains at stable levels in the bloodstream for several hours. Unlike aspirin, the salicylates from willow bark have no effect on blood platelets and do not increase bleeding. Nor does willow bark irritate the lining of the stomach, a common side effect of aspirin. Clinical testing of willow bark has been conducted in England. Researchers at the Centre for Complementary Health Studies at the University of Exeter gave eighty-two participants with chronic arthritic pain either Reumalex, an herbal drug containing willow bark, or a placebo. After two months of use, the willow park medication was found to be superior to the placebo pill.
• Lower back pain and osteoporosis. Studies have shown that willow bark has pain-relieving effects on people with chronic lower back and osteoporitic pain within a week. The herb may be an effective alternative for people who cannot tolerate nonsteroidal anti-inflammatory drugs (NSAIDs). One study found that a combination herbal product containing 100 milligrams of white willow bark reduced pain and improved functioning in people with osteoarthritis.