The American Society of Anaesthesiologists is so concerned about the possible negative interaction between herbal remedies and anaesthetics that they have published a leaflet advising patients to stop their herbal remedies at least two weeks before an operation. If a sudden operation comes up, they advise the patient to inform their doctor of any herbal remedies they have taken recently so that appropriate precautions/changes in procedure can be made.

• Feverfew, ginkgo, ginger and garlic may increase bleeding, especially in patients taking anticoagulants

• Ginseng may decrease the effectiveness of some anticoagulants

• Kava-kava may increase the effect of some anti-seizure medications or prolong the effects of some anaesthetics