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St John's wort and implant — DFSRH MCQ

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ModeratePharmacology of contraceptionSt John's wort and implantDFSRH

A 23-year-old with an etonogestrel implant buys St John's wort for low mood. She has regular sex and does not use condoms. What would you advise this patient?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — St John's wort may reduce implant effectiveness and should be avoided

St John's wort is an enzyme inducer and can reduce the effectiveness of some hormonal contraception including the implant. The patient should be advised to avoid it or use a method unaffected by enzyme induction. Repeated EC is not a reliable planned strategy.

Reference: FSRH Drug Interactions with Hormonal Contraception; BNF