If you have an erection that lasts more than 4 hours, get medical help right away. An evaluation of visual function at doses up to twice the maximum recommended dose revealed no effects of VIAGRA on visual acuity, intraocular pressure, or pupillometry. The products discussed in this site may have different product labeling in different countries. The patient addressed both questions at the final visit for the last 4 weeks of the study. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. Population pharmacokinetic data from patients in clinical trials also indicated a reduction in sildenafil clearance when it was co-administered with CYP3A4 inhibitors such as ketoconazole, erythromycin, or cimetidine [see Dosage and Administration 2.VIAGRA is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil citrate equivalent to 25 mg, 50 mg, or mg of sildenafil. Tablets are debossed with PFIZER on one side and VGR25, VGR50 or VGR on the other to indicate the dosage strengths. Close. Rarely reported side effects include: an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis. sudden vision loss in one or both eyes. Viagra Coupons, Prices, and Savings Card. Generic Names: Sildenafil Citrate. Brand Names: Revatio. Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). Learn more about Viagra oral. 1. This is a generic drug. Even if this drug is covered by Medicare or your insurance, we recommend you compare prices.