Fosamprenavir and Ketoconazole interaction
Fosamprenavir and Ketoconazole: both prescribing labels flag 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
Fosamprenavir calcium/ritonavir: High doses of ketoconazole or itraconazole (greater than 200 mg/day) are not recommended.
Antifungals: Ketoconazole a , itraconazole ↑ Ketoconazole ↑ Itraconazole Increase monitoring for adverse events.
Fosamprenavir calcium: Dose reduction of ketoconazole or itraconazole may be needed for patients receiving more than 400 mg ketoconazole or itraconazole per day.
From the Ketoconazole label · effective 2026-07-07
Drugs that may increase ketoconazole plasma concentrations Potent inhibitors of CYP3A4 (e.g., antivirals such as ritonavir, ritonavir-boosted darunavir and ritonavir-boosted fosamprenavir) may increase the bioavailability of ketoconazole.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
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.