Dosage
As with all prescription drugs, proper dosage is at the discretion of a licensed medical doctor. The dose of sildenafil for erectile dysfunction is 25 mg to 100 mg taken not more than once per day between 30 minutes and 4 hours prior to sexual intercourse.
It is usually recommended to start with a dosage of 50 mg and then lower or raise the dosage as appropriate. The drug is sold in three dosages (25, 50, and 100 mg)
The dosage for pulmonary arterial hypertension (Revatio) is one 20 mg tablet three times a day.
Viagra pills are blue and diamond-shaped with the words “Pfizer” on one side, and “VGR xx” (where xx stands for “25″, “50″ or “100″, the dose of that pill in milligrams) on the other.
Revatio pills, which are used for PAH, are white, round, film-coated tablets imprinted with “RVT 20″ on one side and “Pfizer” on the other.
