They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. A newer form of the medicine that dissolves on the tongue might work faster than the pill that you swallow. Find out whether Viagra is covered under the prescription coverage component of your insurance plan. Medicines that you take by mouth are called oral medicines.Viagra (sildenafil): As the first FDA-approved PDE5 inhibitor for ED, sildenafil is taken Viagra is usually taken only when needed, 30 minutes to 1 hour before sexual activity. You may take it up to 4 hours before sexual activity. Stop taking sildenafil and get . 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.