What the FDA labels say about taking them together
Nelfinavir and sildenafil
Nelfinavir's FDA label of December 11, 2025 names sildenafil in its contraindications section; the sildenafil labels PlainMeds reads (4) do not name nelfinavir. The nelfinavir label: “A safe and effective dose has not been established when used with nelfinavir. There is increased potential for sildenafil-associated adverse events.”
Check it at the source: the nelfinavir FDA label on DailyMed (effective December 11, 2025, AGOURON); the sildenafil FDA label on DailyMed (effective November 17, 2023, Viatris Specialty LLC).
What does the nelfinavir label say about sildenafil?
Nelfinavir label, contraindicationsDrug Class: PDE5 Inhibitors; Drugs Within Class That Are Contraindicated With VIRACEPT: Sildenafil (Revatio ®) [for treatment of pulmonary arterial hypertension] See, for coadministration of sildenafil and tadalafil when dosed for erectile dysfunction.; Clinical Comment: A safe and effective dose has not been established when used with nelfinavir. There is increased potential for sildenafil-associated adverse events (which include visual disturbances, hypotension, prolonged erection, and syncope).
Nelfinavir label, drug interactionsConcomitant Drug Class/Drug Name: Sildenafil Vardenafil Tadalafil; Effect on Concentration: ↑ PDE5 Inhibitors; Clinical Comment: Concomitant use of PDE5 inhibitors and VIRACEPT should be undertaken with caution. May result in an increase in PDE5 inhibitor-associated adverse events, including hypotension, syncope, visual disturbances, and priapism. Use of PDE5 inhibitors for pulmonary arterial hypertension (PAH): • Use of sildenafil (REVATIO) is contraindicated when used for the treatment of pulmonary arterial hypertension (PAH) [see]. …
Source: FDA drug label (VIRACEPT), AGOURON, effective December 11, 2025 (SPL set e72c2bc6-9462-4a2e-8e1d-b97592376cbd), via openFDA; the full label on DailyMed
What does the sildenafil label say about nelfinavir?
Sildenafil's label (effective November 17, 2023) and its 3 other brand-application labels do not name nelfinavir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Viagra), Viatris Specialty LLC, effective November 17, 2023 (SPL set d905dc8d-917f-4ea3-a4ee-a1ecf6967d4e), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Nelfinavir | Sildenafil | |
|---|---|---|
| Labeled for | HIV | Erectile dysfunction, Pulmonary arterial hypertension |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.132 per tablet 100 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once