This medicine usually begins to work for erectile dysfunction within 30 minutes after taking it. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. This medicine comes with a patient information leaflet. The amount of medicine that you take depends on the strength of the medicine. Do not keep outdated medicine or medicine no longer needed. Vardenafil usually works for 4 to 5 hours.Compare prices and print coupons for Viagra (Sildenafil) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ Welcome! You’re in GoodRx Provider Mode. Pay undefined at CVS Pharmacy with a GoodRx discount. That’s 74% off the retail price of $ CVS Pharmacy. $1, retail. Save 74% $ chevron_right. This means that 4 hours after you take a dose, your body has cleared half of the dose. In most cases, it takes about 5 half-lives for your body to completely remove a drug from your system. So. Viagra comes as an oral tablet in different dosages. Discuss with your doctor what’s an appropriate dose for you. For daily use, Goldstein said, the generic form, sildenafil, comes in mg tablets.