Background: Feverfew (Tanacetum parthenium L.) extract is a herbal remedy used for preventing attacks of migraine.
Objectives: To systematically review the evidence from double-blind randomised controlled trials (RCTs) assessing the clinical efficacy and safety of feverfew versus placebo for preventing migraine.
Search strategy: Publications describing (or which might describe) double-blind RCTs of feverfew extract for migraine were sought through the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2003); PREMEDLINE/MEDLINE (1966 to July 2003); EMBASE (1974 to July 2003); the trials register of the Cochrane Pain, Palliative and Supportive care group (July 2003); and AMED (1985 to July 2003). Manufacturers of feverfew were contacted and the bibliographies of identified articles checked for further trials.
Selection criteria: Randomised, placebo-controlled, double-blind trials assessing the efficacy of feverfew for preventing migraine were included. Trials using clinical outcome measures were included. Trials focusing exclusively on physiological parameters were excluded. There were no restrictions regarding the language of publication.
Data collection and analysis: Data on patients, interventions, methods, outcome measures, results and adverse events were extracted systematically. Methodological quality was evaluated using the scoring system developed by Jadad and colleagues. Two reviewers independently selected studies, assessed methodological quality and extracted data. Disagreements concerning evaluation of individual trials were resolved through discussion.
Main results: Five trials (343 patients) met the inclusion criteria. Results from these trials were mixed and did not convincingly establish that feverfew is efficacious for preventing migraine. Only mild and transient adverse events were reported in the included trials.
Reviewer's conclusions: There is insufficient evidence from randomised, double-blind trials to suggest an effect of feverfew over and above placebo for preventing migraine. It appears from the data reviewed that feverfew presents no major safety problems.