They also use telehealth to process the order. Its effects often last for 4 to 5 hours. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. When you buy through links on our site, we may earn an affiliate commission. You can take it in a small dose daily or in a larger dose as needed. This medicine also works best when you take it an hour before sex on an empty stomach. It lasts 4 to 5 hours, or longer if you have mild to moderate ED.This Savings Offer cannot be combined with any other rebate/offer, free trial, or similar offer for the specified prescription; This Savings Offer will be accepted only at participating pharmacies; This Savings Offer is not health insurance; This Savings Offer is good only in the U.S. and Puerto Rico. Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is mg. Don’t take sildenafil (Viagra) more than once daily (at any dose). Written by Brian Leonard, PharmD, BCACP, BCGP. Consumer Reports Best Buy Drugs shares how you might be able to get generic Viagra, known as sildenafil, at a much lower price.