The Pharmaceutical Journal
Vol 276 No 7400 p560
13 May 2006

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Bleeding risk for those who use warfarin and camomile

A case of multiple internal haemorrhages attributed to an interaction between warfarin treatment and excessive use of camomile products has been described by Canadian researchers.

A 70-year-old woman treated with warfarin after having a mechanical mitral valve fitted was admitted to hospital with internal haemorrhaging after drinking four to five cups of camomile tea daily to soothe upper respiratory tract symptoms and using camomile lotion four to five times daily to alleviate foot oedema.

The researchers suggest that the coumarin constituent of camomile may have worked in synergy with warfarin. “Patients should be educated about the potential risk of using herbal products in general, and camomile products in particular, while being treated with warfarin,” they conclude (CMAJ 2006;174:1281).