The manufacturers of sildenafil contraindicate the concurrent use of sildenafil and organic
nitrates (e.g. glyceryl trinitrate (
nitroglycerin),
isosorbide dinitrate, isosorbide mononitrate) because potentially serious hypotension can occur, and myocardial infarction may possibly be precipitated. A number of fatalities have occurred as a result of this interaction. Tadalafil and vardenafil interact similarly.
The concurrent use of these phosphodiesterase inhibitors and all organic
nitrates is contraindicated. Sildenafil should not be used within 24 hours of a nitrate, and some evidence suggests this is also a suitable separation for vardenafil.
Nitrates should not be given for at least 48 hours after the last dose of
tadalafil.