A starting oral dose of 25 mg should be considered in those patients [see Dosage and Administration 2. There were highly statistically significant improvements on the two principal IIEF questions frequency of successful penetration during sexual activity and maintenance of erections after penetration on VIAGRA compared to placebo. The patent was published in and expired in Do not stop taking sildenafil without talking to your doctor. Tell your doctor if any of these symptoms are severe or do not go away: headache. Sexual function data were also recorded by patients in a daily diary. Ask your pharmacist for a list of the ingredients.The average length of time Viagra lasts. On average, Viagra lasts between 2 and 3 hours before its effects start to diminish. Viagra can last up to 5 hours or longer depending on your dosage, your. Compare prices and print coupons for Sildenafil (Generic Revatio and Viagra) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ 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 compared with .