Combining sildenafil (Viagra) with nitrate medications (nitroglycerin, isosorbide) can cause a sudden, severe, and potentially fatal drop in blood pressure. This combination is absolutely contraindicated. Even a single dose of sildenafil within 24 hours of nitrate use can be life-threatening.
How This Interaction Works (Mechanism)
Nitrates release nitric oxide (NO), which activates guanylate cyclase to produce cGMP, causing smooth muscle relaxation and vasodilation. Sildenafil inhibits phosphodiesterase-5 (PDE5), the enzyme that breaks down cGMP. When both drugs are present, cGMP accumulates massively in vascular smooth muscle, causing profound systemic vasodilation and a catastrophic drop in blood pressure that cannot be easily reversed.
Source: American Heart Association Scientific Statement on PDE5 Inhibitors, 2024
Never take sildenafil (or tadalafil, vardenafil, or avanafil) if you use any form of nitrate medication, including nitroglycerin tablets, patches, sprays, or isosorbide mononitrate/dinitrate. This also includes recreational nitrates (amyl nitrite or "poppers"). If you experience chest pain while taking sildenafil, tell emergency responders that you have taken a PDE5 inhibitor so they do not administer nitrates. Wait at least 24 hours (48 hours for tadalafil) between these medications.
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Sildenafil and Nitrates have a severe interaction and should generally not be taken together without close medical supervision. The combination can cause serious, potentially life-threatening side effects. Contact your doctor immediately if you are currently taking both medications.
Combining sildenafil (Viagra) with nitrate medications (nitroglycerin, isosorbide) can cause a sudden, severe, and potentially fatal drop in blood pressure. This combination is absolutely contraindicated. Even a single dose of sildenafil within 24 hours of nitrate use can be life-threatening.
Yes. Anytime you are taking multiple medications, supplements, or substances, you should inform your doctor and pharmacist. They can evaluate your specific risk factors (age, kidney function, other medications, medical conditions) and determine whether the Sildenafil and Nitrates combination is safe for you, or whether adjustments are needed.
Related Resources
- Supplement interactions with Sildenafil on Health Britannica
- Supplement interactions with Nitrates on Health Britannica
- Sildenafil prices and pharmacy comparison on RxGrab
- Nitrates prices and pharmacy comparison on RxGrab
- Full drug interaction checker tool
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