When taken at the correct time and paired with sexual stimulation, the erection lasts long enough for successful intercourse. And not all online pharmacies have the capability to safely ship medications that need to be temperature-controlled, such as insulin. Patients should always ask their doctors for medical advice about adverse events. Popular ED medications found online include: Viagra sildenafil : As the first FDA-approved PDE5 inhibitor for ED, sildenafil is taken 30 minutes to four hours before sexual intercourse to help achieve and maintain an erection. Erectile dysfunction medications require a prescription from a licensed provider. Take sildenafil exactly as directed.About sildenafil (Viagra) Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when. This is a generic drug. The average cost for 30 Tablet(s), mg each of the generic (sildenafil citrate) is $ You can buy sildenafil citrate at the discounted price of $ by using the MDRx coupon, a savings of 43%. Even if this drug is covered by Medicare or your insurance, we recommend you compare prices. VIAGRA is available by prescription only in 25 mg, 50 mg, and mg tablets. Patients should always ask their doctors for medical advice about adverse events. You are encouraged to report adverse events related to Viatris products by calling (U.S. only). If you prefer, you may contact the U.S. Food and Drug Administration (FDA.