Feverfew (Tanacetum parthenium) is a common European composite herb with daisylike white flowers now widely naturalized in the United States. While its name (a corrupted version of the Latin febrifugia) indi-cates a long history in herb lore, feverfewâ€™s current pop-ularity is due to its use in the prevention and treatment of migraines. Feverfew has also been used for rheuma-toid arthritis and numerous other conditions with far less substantiation. The leaves contain sesquiterpene lactones, including parthenolide, which is thought to be the most active and important ingredient. Feverfew preparations are frequently standardized for partheno-lide content, which can vary substantially depending on time of harvest (levels drop after seeds form) and other factors. Most studies have used feverfew standardized to 0.6 to 0.7% parthenolide; the value of leaves con-taining less than 0.2% parthenolide is questionable.
Parthenolide inhibits serotonin release, an action that is thought to be a likely source of its effectiveness in mi-graine. Extracts have also been shown to reduce the production of prostaglandins (another possible mecha-nism) and leukotrienes. Interestingly, melatonin has been identified in feverfew, a possibly significant obser-vation, since chronic migraines have been associated with low melatonin levels.
At least three studies have demonstrated that feverfew (dried leaf, not extract) can reduce the frequency and severity of migraine headaches, although one study failed to find any significant difference from placebo. Pro-phylaxis appears to be more effective than acute treat-ment. There is also a consensus that feverfew is probably less effective than conventional migraine prophylaxis, al-though it may have a role as a second-line option. Although feverfew has also been used for rheumatism, it has never been verified to be effective in clinical trials.
Although feverfew appears generally safe in nonpreg-nant adults, the use of fresh leaves has caused mouth ir-ritation and even ulceration. This is far less likely to occur when the herb is encapsulated. Allergic reactions (contact dermatitis) have occurred with topical use in sensitized individuals, and ingestion may also produce allergic reactions in people with preexisting allergies to members of the Compositae family. Feverfew has caused contractions in term pregnancy and has been implicated in cattle abortions and so should be avoided in preg-nancy and lactation. A feverfew withdrawal syndrome consisting of joint pain and muscle stiffness may occur following abrupt discontinuation. Theoretically, because of its antiprostaglandin effects, feverfew should not be coadministered with anticoagulants or antiplatelet drugs.
For migraine prophylaxis: 50 to 125 mg per day with food, preferably in capsule form to prevent mouth irritation.
Feverfew may be considered as an alternative migraine prophylaxis regimen in patients failing to respond to conventional therapy. It has not been shown to be ef-fective for rheumatoid arthritis. There is insufficient ev-idence to support its use in other conditions.