Viagra (sildenafil citrate) is a prescription medication manufactured by Pfizer. It’s one of the first drugs that actually helped to solve the problem of male impotence. Every patient should consult a doctor before taking Viagra to establish whether the condition they have is actually erectile dysfunction. Being effective for most men in spite of their age and health condition, Viagra works by dilating the blood vessels in the penis allowing more blood to flow in. As the result, the patient is able to achieve a stable erection for long enough to compete sexual intercourse. The pill needs to be taken about 40 minutes before you are planning to have sex and will remain effective during the next three to four hours.

Depending on the condition, the doctor may prescribe a higher or lower dosage of this drug for you to benefit most. Certain conditions may require a dose adjustment – for example, men older than 65, or patients with kidney or liver problems, as well as those taking ketoconazole, erythromycin, ritonavir, itraconazole, or saquinavir usually need a lower dose (25 mg). However, the 25 mg Viagra works just as well for them – it’s just the matter of safety and optimal efficiency.