Feverfew, adverse effects

No significant adverse effects are known to result from typical doses of feverfew (Gruenwald 1998). 

As Tanacetum parthenium is rich in allergenic sesquiterpene lactones, such as parthenolide, it is not surprising that contact dermatitis has been observed (SEDA-11, 426). The most common adverse effect of oral feverfew is mouth ulceration. A more widespread inflammation of the oral mucosa and tongue, swelhng of the lips, and loss of taste have also been reported. 

Systematic reviews of clinical trials on feverfew indicate that the herb is generally well tolerated with few adverse effects (Ernst and Pittler 2000 Pittler and Ernst 2004). No adverse effects were observed in a dose escalation study of a standardized feverfew extract at doses up to 1 g daily (Curry et al. 2004). 

In a survey of 270 migraine patients who had been self-treating their headaches by chewing several feverfew leaves daily for 2 to 4 years, 18% of respondents reported adverse effects. The most frequent complaint was canker sores reported by 11.3% of respondents, although only 7% discontinued therapy. Other complaints included sore tongue, abdominal pain, indigestion, tingling sensation, urinary problems, and headaches (Johnson 1983). Canker sores are believed to be a systemic effect that resolves... 

Limited information on the safety of feverfew during pregnancy and lactation is available. Animal studies with high doses of feverfew in pregnant rats or on isolated rat fetuses have shown some adverse effects on the fetus (Yao et al. 2006). Based on this information, use during pregnancy is not recommended except under the supervision of a qualified healthcare practitioner. 

Curry, E.A., 3rd, D.J. Murry, C. Yoder, et al. 2004. Phase I dose escalation trial of feverfew with standardized doses of parthenolide in patients with cancer. Invest. New Drugs 22(3) 299-305. De Smet, P.A.G.M. 1992. Adverse effects of herbal drugs. Volume 1. Berlin Springer. 

A study of the genotoxicity of feverfew in humans examined the number of sister-chromatid exchanges in feverfew users compared with nonusers and indicated that no adverse effects of feverfew were found. The mutagenicity of urine samples from feverfew users was tested using the Ames mutagenicity test. The frequency of chromosomal aberrations was lower in the feverfew group than in the control group (Johnson et al. 1987). 

Yao, M., P.D. Brown-Woodmari, and H. Ritchie. 2003. Do the herbal remedies feverfew and valerian have an adverse effect on pregnancy outcome in the rat Birth Defects Res. A Clin. Mol. Teratol. 67(2) 145-146. 

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