James L. Gross, D.O.

In clinical trials, the most common adverse effects of sildenafil use included headache, flushing, dyspepsia, nasal congestion and impaired vision, including photophobia and blurred vision. Some sildenafil users have complained of seeing everything tinted blue. Some patients complained of blurriness and loss of peripheral vision. In July 2005, the U.S. Food and Drug Administration found that sildenafil could lead to vision impairment in rare cases and a number of studies have linked sildenafil use with nonarteritic anterior ischemic optic neuropathy.

Rare but serious adverse effects include priapism, severe hypotension, myocardial infarction (heart attack), ventricular arrhythmias, stroke, increased intraocular pressure, and sudden hearing loss As a result of these post marketing reports, in October 2007, the FDA announced that the labeling of sildenafil required a more prominent warning of the potential risk of sudden hearing loss.

Interactions

Care should be exercised by patients that are also taking protease inhibitors for the treatment of HIV. Protease inhibitors inhibit the metabolism of sildenafil, effectively multiplying the plasma levels of sildenafil increasing the incidence and severity of side effects.

Concomitant use of sildenafil and an alpha blocker may lead to low blood pressure, but this effect does not occur if they are taken at least four hours apart.

Contraindications

When taking nitric oxide donors, organic nitrites and nitrates, such as glyceryl trinitrate (nitroglycerin), sodium nitroprusside, amyl nitrite

In men for whom sexual intercourse is inadvisable due to cardiovascular risk factors

Severe hepatic impairment (decreased liver function)

Severe impairment in renal function

Hypotension (low blood pressure)

Recent stroke or heart attack

Hereditary degenerative retinal disorders (including genetic disorders of retinal phosphodiesterases)