Sildenafil has been around since 1998, so there is a lot of information about its benefits and drawbacks.
It starts working within an hour of taking the medication and should be taken on an empty stomach for the best results. Sildenafil’s effects typically last four to five hours.
Viagra’s active ingredient is sildenafil. Pfizer, the pharmaceutical company, developed Viagra, and they were the only ones who could legally manufacture it until 2013.
Their patent expired in 2013, allowing other companies to produce erectile dysfunction medications containing sildenafil as the active ingredient.