Atazanavir and Sildenafil interaction
Atazanavir and Sildenafil: 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 Atazanavir (REYATAZ) label · effective 2024-12-05
…following drugs listed in Table 6: Table 6: Drugs Contraindicated with REYATAZ (Information in the table applies to REYATAZ with or without ritonavir, unless otherwise indicated) a See Drug Interactions, Table 16 (7) for parenterally administered midazolam. b See Drug Interactions, Table 16 (7) for sildenafil when dosed as VIAGRA ® for erectile dysfunction.
John’s wort ( Hypericum perforatum ) Lipid-Modifying Agents: Lomitapide, lovastatin, simvastatin Phosphodiesterase-5 (PDE-5) Inhibitor Sildenafil b when dosed as REVATIO ® for the treatment of pulmonary arterial hypertension Protease Inhibitors Indinavir Non-nucleoside Reverse Transcriptase Inhibitors Nevirapine • In patients with previously demonstrated hypersensitivity…
PDE5 inhibitors: sildenafil, tadalafil, vardenafil ↑ sildenafil ↑ tadalafil ↑ vardenafil Coadministration with REYATAZ has not been studied but may result in an increase in PDE5 inhibitor-associated adverse reactions, including hypotension, syncope, visual disturbances, and priapism.
Use of PDE5 inhibitors for erectile dysfunction: Use VIAGRA ® (sildenafil) with caution at reduced doses of 25 mg every 48 hours with increased monitoring for adverse events.
Use of PDE5 inhibitors for pulmonary arterial hypertension (PAH): Coadministration of REYATAZ with REVATIO ® (sildenafil) for the treatment of pulmonary hypertension (PAH) is contraindicated [see Contraindications (4) ] .
From the Sildenafil label · effective 2026-07-17
Adverse Reactions with the Concomitant Use of Ritonavir The concomitant administration of the protease inhibitor ritonavir substantially increases serum concentrations of sildenafil (11-fold increase in AUC).
CYP3A4 inhibitors (e.g., ritonavir, ketoconazole, itraconazole, erythromycin) increase SILDENAFIL ORAL FILM exposure.
Erythromycin or strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, saquinavir): Consider a starting dose of 25 mg.
Ritonavir and other CYP3A4 inhibitors Co-administration of ritonavir, a strong CYP3A4 inhibitor, greatly increased the systemic exposure of sildenafil (11-fold increase in AUC).
Co-administration of erythromycin, a moderate CYP3A4 inhibitor, resulted in 160% and 182% increases in sildenafil Cmax and AUC, respectively.
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.