The safe gap between sildenafil and a nitrate is not on record
A widely cited review reports the interaction undetectable by 24 hours after a dose. The approved US label names no interval and says it is unknown.
What the study found
Nobody will say how long you must wait before a nitrate
A widely cited review reports the interaction between sildenafil and nitrates as undetectable by 24 hours after a dose. The approved US label names no interval at all, saying it is unknown when a nitrate can safely be given afterwards. The gap falls on whoever is holding the nitrate spray.
The caveat · One author with industry ties
The review is narrative rather than systematic, written by a single author with long-standing industry ties in this field and published in a journal supplement. A label naming no interval is not evidence that no interval is safe; it is a regulator declining to guess.
What we don't know
How long after sildenafil a nitrate becomes safe has no agreed answer. One review finds the interaction gone by 24 hours; the US regulator, with the same interaction studies in hand, declines to name any interval.