Your doctor may adjust your dose as needed and tolerated. If you take too much sildenafil or take it together with these medicines, the chance for side effects will be higher. If you are taking sildenafil for PAH, take the missed dose as soon as you remember it. Ask your healthcare professional how you should dispose of any medicine you do not use. Sildenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus HIV. Before taking sildenafil, tell your doctor and pharmacist if you are allergic to sildenafil, any other medications, or any of the ingredients in sildenafil tablet or suspension.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. F W RICHARDS JR INC. $ N Main St. Chase City, VA mi. Closed. () Get Coupon. 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 .