The molecular composition of its active substance, Sildenafil, will begin to break down over time — and it may not have the inhibiting effect on this enzyme that it was designed to have. And what happens if you take the ED drug after its expiry date? Popular searches. Your recent eating habits. Eating a high-fat meal before using Viagra may affect how long it takes to work and increase the amount of time that Viagra is active.There are several medications and treatments used to treat erectile dysfunction (ED, impotency), including Viagra (sildenafil), testosterone replacement therapy, penile self . Generic Viagra (sildenafil) is an alternative to the branded Viagra drug that can be used for treating erectile dysfunction (ED). It’s now sold by many manufacturers, including online. And what’s its shelf-life? You should store Viagra at a temperature of 77°F (25°C). If needed, you can store this medication between 59°F and 86°F (15°C and 30°C) for a .