What the FDA labels say about taking them together
Isosorbide mononitrate and sildenafil
Isosorbide mononitrate's FDA label of May 11, 2026 names sildenafil in its warnings section; sildenafil's label does not name isosorbide mononitrate itself but warns about its class (nitrate vasodilators). The isosorbide mononitrate label: “Do not use isosorbide mononitrate in patients who are taking certain drugs for erectile dysfunction, such as sildenafil, tadalafil, or vardenafil.”
Check it at the source: the isosorbide mononitrate FDA label on DailyMed (effective May 11, 2026, Torrent Pharmaceuticals Limited); the sildenafil FDA label on DailyMed (effective November 17, 2023, Viatris Specialty LLC).
What does the isosorbide mononitrate label say about sildenafil?
Isosorbide mononitrate label, warningsWARNINGS Amplification of the vasodilatory effects of isosorbide mononitrate by sildenafil can result in severe hypotension.
Isosorbide Mononitrate label (OMNIVIUM PHARMACEUTICALS LLC., August 6, 2025), contraindicationsDo not use isosorbide mononitrate in patients who are taking certain drugs for erectile dysfunction (phosphodiesterase inhibitors), such as sildenafil, tadalafil, or vardenafil.
Source: FDA drug label (Isosorbide Mononitrate, NDA020215), OMNIVIUM PHARMACEUTICALS LLC., effective August 6, 2025 (SPL set cdf01e14-778b-4b3f-8372-1c18f266fb98), via openFDA
Source: FDA drug label (ISOSORBIDE MONONITRATE), Torrent Pharmaceuticals Limited, effective May 11, 2026 (SPL set 0a1e317a-7b05-4d30-9bbc-1d4ccd56ba3c), via openFDA; the full label on DailyMed
What does the sildenafil label say about isosorbide mononitrate?
Sildenafil's label does not name isosorbide mononitrate itself; it warns about its class (nitrate vasodilators):
Sildenafil label, contraindicationsCONTRAINDICATIONS Administration of VIAGRA to patients using nitric oxide donors, such as organic nitrates or organic nitrites in any form.
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.
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
| Isosorbide mononitrate | Sildenafil | |
|---|---|---|
| Labeled for | Angina | Erectile dysfunction, Pulmonary arterial hypertension |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0688 per tablet 30 mg tablet | $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