Although not all of these side effects may occur, if they do occur they may need medical attention. Use only the brand of this medicine that your doctor prescribed. Injections are dosed at 2. It’s available in 50 mg, mg, and mg tablets. The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes.If you have these symptoms, stop taking VIAGRA and contact a doctor right away. have or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure. have low blood pressure, or high blood pressure that is not controlled. Archive. Your daily dose of entertaining, useful and informative lists. Search. Input your search keywords and press Enter. If you’re looking . 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.