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MAOI and SSRI interaction — GPhC CRA MCQ

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HardDrug InteractionsMAOI and SSRI interactionGPhC CRA

A 45-year-old man taking phenelzine is prescribed fluoxetine 20 mg daily after reporting low mood to an out-of-hours prescriber. He collected phenelzine 2 weeks ago and says he took it this morning. What is the most important interaction to flag?

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Correct answer: B — Phenelzine with fluoxetine may cause serotonin syndrome

Combining an MAOI with an SSRI is contraindicated because of the risk of serotonin syndrome. Washout periods are required when switching between these medicines. The pharmacist should not supply fluoxetine without urgent clarification and should assess for symptoms such as agitation, tremor, sweating and diarrhoea.

Reference: BNF