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Antibiotics and COC — DFSRH MCQ

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HardPharmacology of contraceptionAntibiotics and COCDFSRH

A patient taking St John’s wort presents 48 hours after unprotected intercourse and wants the most effective emergency method plus ongoing contraception. What should be offered first?

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Correct answer: E — A copper IUD after emergency-IUD eligibility assessment

The best answer is “A copper IUD after emergency-IUD eligibility assessment”. St John’s wort induces hepatic enzymes and can reduce the effectiveness of oral emergency contraception and several hormonal methods. A copper IUD is the most effective emergency option and is unaffected by enzyme induction; it can remain for ongoing contraception. If an IUD is declined or unsuitable, oral alternatives require specific enzyme-inducer advice rather than routine dosing assumptions.

Reference: CoSRH/FSRH, Drug Interactions with Hormonal Contraception (May 2022): https://www.cosrh.org/Common/Uploaded%20files/documents/drug-interactions-with-hormonal-contraception-5may2022.pdf