Never take 2 doses at the same time. This medicine also works best when you take it an hour before sex on an empty stomach. Continuing Education Activity Sildenafil is a medication used in the management and treatment of erectile dysfunction and pulmonary arterial hypertension. Rarely reported side effects include: an erection that will not go away priapism. Ask your pharmacist for a list of the ingredients.The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex. For sildenafil to work properly, you’ll need to be sexually excited. According to price-comparison site test1.ru, generic Revatio will cost you as little as $ per pill, depending on where you fill your prescription. That’s .  · GoodRx may be able to help you save over 95% off the average retail price of generic Viagra at certain pharmacies. The average retail price of the most common prescription of sildenafil could cost a couple hundred dollars, but you might be able to get that same prescription for as little as $11 with a GoodRx coupon.