Viagra (sildenafil) is a drug commonly used to treat ED, a condition that over 150 million people worldwide are estimated to be affected by. While the brand name prescription comes in a blue pill form, generic sildenafil comes in a white pill.
Though generic sildenafil can also be used to treat pulmonary arterial hypertension, only Revatio-equivalent sildenafil is approved by the FDA for this particular condition. Viagra's generic for erectile dysfunction is prescribed in 25 mg, 50 mg, and 100 mg tablets.
When you're aroused, your body releases nitric oxide down below - a molecule that triggers the events responsible for an erection. But an enzyme (protein) called phosphodiesterase type 5 (PDE5) breaks down certain messengers involved in this process, preventing the desired effect.
While there are a number of reasons why someone may have difficulty getting or maintaining an erection, PDE5 inhibitors that block this enzyme, like Viagra, are often used to help.