First 12 minutes. The body quickly absorbs Sildenafil and it’s found some men get an erection within 12 minutes of popping a viagra.
60 minutes. An hour marks a crucial point with Sildenafil as after nearly 50 minutes have passed you’ll reach the “maximum erection potential”. This is when the drug reaches its highest concentration in the blood, which explains why doctors advise taking one an hour before sex. According to the study, men can have erections lasting up to 33 minutes within an hour of taking the drug.
Four hours. It’s possible you may still be able to have sex, although the effects of the Sildenafil will be steadily reducing.
10 hours. Even after 10 hours, scientists found men still could get an erection – and found it just as easy as it was two hours after dosing up.
12 hours. It’s still possible to have sex, but with the average erection lasting 16 Minutes
24/7 : After one day the effects of Sildenafil will have worn off. Almost all traces of the drug disappear from the blood stream, along with any boost to sexual performance. Hint Hint Nudge Nudge
None of the above explains what happens beyond the mechanics of an erection. When I get aroused naturally, my dick gets like a crowbar when I am really turned on. Such as after a week of abstinence. Arousal is first, then the hardness. Does Viagra just give me the hard-on? I’ve never understood.
It was actually intended to prevent ischemic events originally. People forget that drugs often have multiple uses simply because they act the same way throughout the body. Viagra increases blood flow to the heart and brain (the original purpose) but also to the penis (what it’s mostly used for now) and to the eye (and those capillaries can burst, leading to blindness, really bad side effect).