That's OK—there are many potential reasons why. Viagra may not work effectively if you ate a heavy meal or drank a lot of alcohol before taking it, or took it at a less-than-optimal time before sex. ED could also be a sign of an underlying health condition you're not being treated for.

What happens if sildenafil doesn't work?

If Viagra doesn't seem to work for you, try taking it two to three hours after your last meal. Wait for Viagra to kick in. Viagra works quickly, but its effects aren't instant. It's best to take Viagra at least one hour before you plan to have sex, as this gives your body time to fully absorb the medication.

Why does Viagra not work for me anymore?

There are a number of reasons why Viagra may no longer work. Most commonly it may be that it is bad luck – you may not have taken it properly or did not give it enough time to work. You may have been tired or stressed out. If Viagra did not work once, try it again before giving up.