Feverfew Side Effects and Warnings

Safety Issues

Animal studies suggest that feverfew is essentially nontoxic. ¹ In one 8-month study, there were no significant differences in side effects between the treated and control groups. ² There were also no changes in measurements on blood tests and urinalysis.

In a survey involving 300 people, 11.3% reported mouth sores from chewing feverfew leaf, occasionally accompanied by general inflammation of tissues in the mouth. ³ A smaller percentage reported mild gastrointestinal distress. ⁴ However, mouth sores do not seem to occur in people who use encapsulated feverfew leaf powder, the usual form.

In view of its use as a folk remedy to promote abortions, feverfew should probably not be taken during pregnancy.

Because feverfew might slightly inhibit the activity of blood-clotting cells known as platelets, ⁵ it should not be combined with strong anticoagulants, such as warfarin (Coumadin) or heparin, except on medical advice. Feverfew might also increase the risk of stomach problems if combined with anti-inflammatory drugs, such as aspirin. ⁶ Safety in young children, pregnant or nursing women, or those with severe kidney or liver disease has not been established.

Interactions You Should Know About

If you are taking:

• Warfarin (Coumadin), heparin , aspirin , or other nonsteroidal anti-inflammatory drugs : Do not use feverfew except on medical advice.