If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. Phosphodiesterase type 5 PDE5 inhibitors. Which Works Faster? Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. Rarely reported side effects include: an erection that will not go away priapism.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. 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 1 . The maximum dose of Viagra is mg each day. Doses above the maximum dose, such as mg per day, will increase the risk of side effects. And in some cases, this could be serious.