A medicine called Revatio is used to treat erectile dysfunction in male adults. The active ingredient in Revatio is sildenafil citrate, which causes a man to have an erection by expanding and relaxing the blood vessels in the penile region. Revatio is only available as tablets, which have to be used orally. But pulmonary hypertension is another condition for which this drug is prescribed. There are various Revatio variations available. Before using Revatio, you should be aware of the following significant side effects:  Heart Attack symptoms such as perspiration, nausea, or chest pain abrupt loss of vision extended erection (about four hours)