A patient has replaced conventional medication with natural remedies, including garlic and St John's wort. What is the MOST important precaution before invasive dental treatment?

Correct answer: A. Anticipate an increased risk of bleeding

• A. Correct. Several herbal supplements carry real ANTIPLATELET and ANTICOAGULANT effects — remember the 'G' herbs: GARLIC, GINKGO, GINGER and GINSENG, plus vitamin E and fish oil. Garlic inhibits platelet aggregation, and prolonged bleeding after oral surgery is well documented. ST JOHN'S WORT is a potent CYP3A4 and P-glycoprotein INDUCER that accelerates metabolism of a long list of drugs including warfarin, oral contraceptives, benzodiazepines and some analgesics, and it carries serotonin syndrome risk with tramadol. Always ask specifically about supplements — patients routinely omit them when asked about medications.
• B. There is no established prolongation of local anaesthetic effect.
• C. Herbal supplements are not associated with a general increase in infection risk.
• D. The assumption that 'natural' means 'no interaction' is precisely the error this question tests.

Note: The source suggested avoiding epinephrine. The better-evidenced and more examinable concern with garlic and St John's wort is BLEEDING RISK plus CYP3A4 induction, not an epinephrine interaction. Discuss as a group.