Feverfew

Feverfew, Tanacetum parthenium, is a member of the Asteraceae family. Other common names of feverfew include featherfew, febrifuge plant, and wild chamomile. The leaves of the plant are most commonly used in herbal preparations.

Uses and Benefits:

Feverfew has been used traditionally by herbalists for headaches, arthritis, menstrual irregularity, difficulties in labor, psoriasis, stomach ache, asthma, and fever.It gained popularity in Great Britain in the 1980s as a headache remedy and is now commonly used for migraine prophylaxis as well as for other painful disorders such as arthritis.

Pharmacology:

The numerous constituents of feverfew in­clude sesquiterpene lactones, monoterpenes, flavonoids, polyacetylenes, and an essential oil. The sesquiterpene lactones, of which parthenolide is the major constituent, were initially thought to be most important. Parthenolide is found in many other plants, and the concentrations vary widely among different chemotypes of T. parthenium species grown in different geographic areas.

Clinical Trials:

In an initial uncontrolled survey of 270 migraine patients in Great Britain, over 70% of patients reported improve­Illents when eating an average of 2-3 fresh leaves of feverfew daily over several months to years. Subsequently, six double­blind randomized controlled trials from outside the U.S. have eval­uated feverfew for the prophylaxis of migraine headaches four studies found beneficial results.

Although the overall results suggest that feverfew may be ben­eficial for migraine headaches, methodologic quality of these studies was questioned in a critical systematic review.B,g None of the crossover-design trials contained adequate washout periods; intention-to-treat analyses were not performed in two positive studies; and one negative trial was considered to have the high­est methodologic quality. The reviewers emphasized that while feverfew may have beneficial effects for migraine prophylaxis, firm conclusions cannot be drawn from the literature.

 

Adverse Effects:

In an uncontrolled survey of feverfew leaf users, adverse effects Occurred in 18% of 270 patients. The main side effects included oral disturbances (e.g., mouth ulceration, sore tongue, unpleasant taste, swollen lips and mouth) and mild gastrointestinal disturbances, in 9.8% and 4.3% of patients, respectively.Oral side effects appear to be more common when chewing the fresh leaves. Reported side effects from the clinical trials using encapsulated products were similar to placebo (actually less than placebo in two trials).Results of hematologic and biochemical safety tests were also not affected by feverfew products.

The term "post-feverfew syndrome" was coined by one investigator, who reported rebound headache, anxiety, insomnia, and joint and muscle stiffness or pain in about 10% of chronic fever­ few users who discontinued the herb. Other studies have not reported this effect.

Side Effects and Interactions:

Feverfew affects platelet activity in vitro, but this has not been demonstrated in vivo,and there have been no reported clinical cases of untoward laboratory abnormalities, unexpected bleeding, or other interactions in patients wllo were also taking anticoagulant or antiplatelet drugs. Adverse effects on coagulation are thus doubtful, but caution and monitoring is advised for patients at high risk of bleeding. Contact allergy to feverfew is well documented with occupational exposures, , and there is cross-allergenicity between similar plants containing sesquiterpene lactones (e.g., chrysanthemums, ragweed, daisies). The feverfew plant can cause abortions in cattle, and is therefore contraindicated during pregnancy.

Preparations & Doses:

Commercial products usually consist of the leaves or other above-ground parts of the plant, often powdered and freeze-dried; these preparations are presumably safer than chewing the fresh leaves. The daily dose used in successful umtrolled trials was approximately 50-100 mg of encapsulated dried leaf preparations (roughly equivalent to 2-4 fresh leaves), but daily doses of up to 200-600 mg have been recommended by some herbal authorities. Preparations are typically standardized to contain at least 0.2% parthenolide. However, while standardization can be useful to ensure the correct identity of the T. parthenium chemotype, it may not provide an index of effectiveness.

Summary Evaluation

Feverfew has been shown to be beneficial for migraine headache prophylaxis in the majority of randomized controlled trials con­ducted; however, efficacy has not been adequately established beyond a reasonable doubt. Feverfew appears to be safe and well tolerated, and thus it is not unreasonable for chronic migraine suf­ferers to try this herbal medicine. Feverfew has not been investi­gated for treatment of acute migraine attacks or for other types of headaches. It has been found to be ineffective in one trial for rheumatoid arthritis, and none of its other purported clinical uses have been investigated.