It’s available in 25 mg, 50 mg, and mg tablets and lasts up to 18 hours. However, some states require a live video consultation. They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. If you are taking sildenafil for erectile dysfunction, you are unlikely to miss a dose since this medication is taken as needed, not on a regular dosing schedule. People with heart conditions should never take ED medications without consulting a doctor. Often, these are prescribed for chest pain called angina.Oral medicines for ED usually work well and cause few side effects. The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. Follow his or her instructions carefully to help you get the best results from treatment. VIAGRA is available by prescription only in 25 mg, 50 mg, and mg tablets. the dose may be increased to a maximum recommended dose of mg or decreased to 25 mg. Be sure to tell your doctor about all of the medications you take and any other. 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.