What the FDA labels say about taking them together
Nitric oxide and sildenafil
Sildenafil's FDA label of November 17, 2023 names nitric oxide in its contraindications section; the nitric oxide labels PlainMeds reads (2) do not name sildenafil. The sildenafil label: “Administration of VIAGRA with nitric oxide donors such as organic nitrates or organic nitrites in any form is contraindicated.”
Check it at the source: the nitric oxide FDA label on DailyMed (effective December 11, 2025, VERO BIOTECH, INC.); the sildenafil FDA label on DailyMed (effective November 17, 2023, Viatris Specialty LLC).
What does the nitric oxide label say about sildenafil?
Nitric oxide's label (effective December 11, 2025) and its 1 other brand-application label do not name sildenafil in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (GENOSYL), VERO BIOTECH, INC., effective December 11, 2025 (SPL set c9560c54-9e28-4039-a4e5-5000c41c6c85), via openFDA; the full label on DailyMed
What does the sildenafil label say about nitric oxide?
Sildenafil label, contraindicationsConsistent with its known effects on the nitric oxide/cGMP pathway [ see Clinical Pharmacology (12.1 , 12.2) ], VIAGRA was shown to potentiate the hypotensive effects of nitrates, and its administration to patients who are using nitric oxide donors such as organic nitrates or organic nitrites in any form either regularly and/or intermittently is therefore contraindicated.
Sildenafil label, drug interactionsAdministration of VIAGRA with nitric oxide donors such as organic nitrates or organic nitrites in any form is contraindicated.
Sildenafil label, warnings and precautionsHowever, in vitro studies with human platelets indicate that sildenafil potentiates the antiaggregatory effect of sodium nitroprusside (a nitric oxide donor).
Source: FDA drug label (Vybrique, NDA210858), IBSA Pharma Inc., effective July 8, 2026 (SPL set 9213fec1-e0c0-4ef7-9718-d97922a3f4d8), via openFDA
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
| Nitric oxide | Sildenafil | |
|---|---|---|
| Labeled for | n/a | 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