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St John's wort and oral contraceptive — GPhC CRA MCQ

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HardDrug InteractionsSt John's wort and oral contraceptiveGPhC CRA

A patient using a combined oral contraceptive asks to buy St John's wort for low mood. She wants to avoid pregnancy. What is the most important interaction to flag?

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Correct answer: D — St John's wort can reduce contraceptive efficacy

St John's wort is an enzyme inducer and can reduce the effectiveness of hormonal contraception. It also interacts with several antidepressants and other medicines. The patient should be advised not to self-treat low mood with it and to seek appropriate support.

Reference: https://www.pharmacyregulation.org/registration-assessment#stage-8-order-29