Dosage Given the recent confusion surrounding parthenolide, previous dosage recommendations for feverfew based on parthenolide content have been cast in doubt. At the present time, the best recommendation is probably to take 80 to 100 mg of powdered whole feverfew leaf daily. When taken at the onset of a migraine headache, higher amounts of feverfew are often used. However, the optimum dosage has not been determined. Among the many thousands of people who use feverfew as a folk medicine in England, there have been no reports of serious toxicity.
Animal studies suggest that feverfew is essentially nontoxic.
In the 8-month Nottingham trial, there were no significant differences in side effects between the treated and control groups. There were also no changes in measurements on blood tests and urinalysis. A smaller percentage reported mild gastrointestinal distress. 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.