skip to main content

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

Instant feedback + full explanation. One question, done properly.

EasyDrug InteractionsSt John's wort and oral contraceptionGPhC CRA

A 27-year-old woman using a combined oral contraceptive pill asks to buy St John's wort for low mood. She has no current antidepressant prescription. What is the most important interaction to flag?

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

Reveal the answer and explanation

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

St John's wort is an enzyme inducer and can reduce the effectiveness of hormonal contraception. It also interacts with many medicines, including antidepressants and anticoagulants. The patient should be advised against self-treatment and signposted for assessment of mood symptoms.

Reference: BNF; MHRA advice