ART Drug Interaction — SCE Infectious Diseases MCQ

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EasyHIV MedicineART Drug InteractionSCE Infectious Diseases

A 28-year-old man with HIV (CD4 350, VL <50 on ART) attends for routine review. He reports he has been taking St John's Wort for low mood for the past month. What is the clinical significance?

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Correct answer: B — St John's Wort induces CYP3A4 and UGT1A1, potentially reducing INSTI and PI levels — it is contraindicated with most ART

St John's Wort (Hypericum perforatum) is a potent inducer of CYP3A4, CYP2C9, P-glycoprotein, and UGT1A1. It can significantly reduce plasma levels of many antiretrovirals including INSTIs (Dolutegravir, Bictegravir), PIs (Darunavir), and NNRTIs (Rilpivirine, Efavirenz). This can lead to subtherapeutic drug levels, virological failure, and resistance development. St John's Wort is absolutely contraindicated with ART. The patient should stop it immediately and have a viral load checked.

Reference: BHIVA 2025 – ART guidelines; BNF 2024 – St John's Wort interactions; Liverpool Drug Interactions