Three clinical trials of feverfew (Tanacetum parthenium) have found the herb effective for migraine headaches, but ineffective for rheumatoid arthritis (RA). A closer look at these studies gives valuable clinical information.
A double-blind, placebo controlled crossover study—the gold standard in scientific research—found feverfew to reduce migraine attacks from a monthly average of 4.7 to 3.6 in a group of seventy-six patients.(Murphy et al.) For those who find the herb effective, better results may be obtained. Johnson et.al. withdrew feverfew and substituted a placebo in a group of long-term users, and compared results to a group who continued taking the herb. (See table) This self-selected group (i.e. those who found feverfew ineffective had already withdrawn) reported an improvement from 5.5 attacks per month to 1.4.
Both successful trials for migraine used fresh or carefully prepared material. Murphy et al. used feverfew leaves derived from three original plants with high pharmacological activity, carefully dried them and kept them at four degrees C. until used. The RA trial, on the other hand, used dried and powdered feverfew, unassayed for pharmacological activity. Volatile substances are among the active constituents of feverfew, and the dried, powdered form is among the worst for preserving volatiles. A British analysis of commercial feverfew products found a wide range of quality, with some products having no pharmacological activity at all (Groenwegen, et al.) Feverfew may work best for patients willing to grow their own.
The studies show very few side effects, and no significant changes in laboratory results. The Murphy study discounts earlier reports that feverfew may cause mouth ulceration. Sixteen patients in the placebo (cabbage) group reported ulceration, and only ten among the feverfew group. Two of the nine patients in the Johnson study who continued taking feverfew had dramatic increases in heart rate—26 and 20 beats per minute—over the six months of the trial. They were already long term feverfew users before the study, so these changes may not have been due to the herb. Some herbalists in the U.S. have reported increased or new menstrual pain after taking feverfew. (Geller)
of patients, and avoidance of side effects may
be enhanced by observing
the underlying energy patterns of the patients.
Feverfew is a cooling,
bitter herb, ideally suited to fevers and “hot”
conditions. It will be
less useful and may cause side effects in cold,
deficient, and exhausted
Geller, CA. Personal communication. June 1988.
Growenwegen WA; Heptinstall S. “Amounts of fever
few in commercial preparations of the herb.Lancet 1986;i:44-45Johnson ES; Kadam NP; Hylands DM; Hylands PJ. “Efficacy of feverfew as prophylactic treatment of migraine." Brit Med J. 291:569-573