The review of the adverse drug reactions reported in clinical trials indicate that most side-effects are mild and reversible.
Mouth inflammation or ulcers, including swelling of the lips, tongue irritation, bleeding of the gums, and loss of taste have been reported, usually after direct contact of the mouth with the leaves, although some people report burning after swallowing a tablet containing dried leaf.
Photosensitivity (sensitivity to sunlight or sunlamps) has been reported with other herbs in the Asteraceae (Compositae) plant family.
Indigestion, nausea, flatulence, constipation, diarrhoea, abdominal bloating, and heartburn have been reported rarely.
Feverfew can also cause allergic rashes.
Increased heart rate in some patients has been reported in one small study. Other side effects that have been reported spontaneously are eosinophilia, abnormal liver function tests, arthritis, renal failure, Raynaud's phenomenon and hypertension.
These were spontaneously generated adverse drug reactions during post-marketing surveillance and the causal relation to Feverfew cannot be established.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continual monitoring of the benefit/risk of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow card Scheme at www.mhra.gov.uk/yellowcard or search for 'MHRA Yellow Card' in the Google Play or Apple App Store.