Please describe the medication: viagra (sildenafil)?

Erectile dysfunction. Treats erectile dysfunction (trouble having an erection). Helps a man have an erection or have a better erection with his penis during sex. Also treats pulmonary arterial hypertension (high blood pressure in the lungs) in both men and women.
Viagra (sildenafil) Viagrais a medication used to treat erectile dysfunction. It is a phosphodiesterase 5 inhibitor (pde5) in the same family as Levitra (vardenafil) and cialis. Viagra was the first medication of this kind. It last about 4 hours, should be taken on empty stomach without alcohol, 45 min before intercourse. All of these medications are safe but can be dangerous for patients that take nitrate.