Your doctor may adjust your dose if needed. This medicine usually begins to work for erectile dysfunction within 30 minutes after taking it. It works for up to 36 hours. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices.Sildenafil Citrate Coupons, Prices, and Savings Card. Brand Names: Revatio, Viagra. Sildenafil is used to treat male sexual function problems (impotence or erectile . Prices for Sildenafil (Revatio) are as low as $ with a GoodRx coupon. 6 hours. Taking it more frequently can raise your risk of side effects. There is usually no benefit to taking more than 20 mg 3 times a day, though some medical specialists will recommend higher strengths (still taken 3 times a day). White Round R And AdSave on 50, Brand Name & Generic Drugs With SingleCare®. Get Your Free Rx Coupon Now! Find the Lowest Price for Your Prescription and Save at Your Local Pharmacy test1.rue prices · BBB accredited · Select pharmacies · 35, pharmacies/5 (2, reviews)Site visitors: Over K in the past month.