What the FDA labels say about taking them together
Heparin and sildenafil
Sildenafil's FDA label of November 17, 2023 names heparin in its warnings and precautions section; the heparin labels PlainMeds reads (4) do not name sildenafil. The sildenafil label: “In addition, the combination of heparin and VIAGRA had an additive effect on bleeding time in the anesthetized rabbit, but this interaction has not been studied in humans.”
Check it at the source: the heparin FDA label on DailyMed (effective November 28, 2025, Fresenius Kabi USA, LLC); the sildenafil FDA label on DailyMed (effective November 17, 2023, Viatris Specialty LLC).
What does the heparin label say about sildenafil?
Heparin's label (effective November 28, 2025) and its 3 other brand-application labels 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 (Heparin Sodium), Fresenius Kabi USA, LLC, effective November 28, 2025 (SPL set d55b4a63-0c04-4874-b74f-9e9b9e8b008c), via openFDA; the full label on DailyMed
What does the sildenafil label say about heparin?
Sildenafil label, warnings and precautionsIn addition, the combination of heparin and VIAGRA had an additive effect on bleeding time in the anesthetized rabbit, but this interaction has not been studied in humans.
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
| Heparin | Sildenafil | |
|---|---|---|
| Labeled for | Blood clots (DVT and PE), Atrial fibrillation | Erectile dysfunction, Pulmonary arterial hypertension |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $1.18 per mL 5,000 unit/mL vial | $0.132 per tablet 100 mg tablet |
| Shortage now | In shortage | 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