Fosamprenavir and St. John's wort interaction
Fosamprenavir and St. John's wort: the Fosamprenavir prescribing label flags this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Fosamprenavir (Fosamprenavir Calcium) label · effective 2026-06-30
John’s wort ( Hypericum perforatum ) Lipid modifying agents: Lomitapide, lovastatin, simvastatin Non-nucleoside reverse transcriptase inhibitor: Delavirdine PDE5 inhibitor: Sildenafil (Revatio) (for treatment of pulmonary arterial hypertension) Sedative/hypnotics: Midazolam, triazolam Hypersensitivity to fosamprenavir calcium or amprenavir (e.g., Stevens-Johnson…
John’s wort (Hypericum perforatum) ↓Amprenavir Coadministration is contraindicated as it may lead to loss of virologic response and possible resistance to Fosamprenavir calcium or to the class of protease inhibitors [see Contraindications (4)] .
Curated guidance for St. John's wort
St. John's wort can lower blood levels of some HIV medicines enough to cause treatment failure.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.