Sildenafil tablets (25 mg, 50 mg, 100 mg; Viagra, generic) and sildenafil oral film (25 mg, 50 mg, 75 mg, 100 mg; Vybrique) are used for ED. Sildenafil tablets (20 mg; Revatio, generic), sildenafil oral suspension (Revatio, generic), and sildenafil injection (Revatio, generic) are used for PAH. Viagra (sildenafil) is used to treat erectile dysfunction or impotence in men. Includes Viagra side effects, interactions and indications. Learn about sildenafil (Viagra) usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. Viagra (sildenafil) is a brand-name prescription drug that’s used to treat erectile dysfunction (ED). Learn about side effects, warnings, dosage, and more. Take sildenafil at least 30 minutes, but no more than 4 hours, before sexual activity (1 hour before works best). This medication may take longer to start working if you take it with a high-fat meal. Do not take more than once daily as needed. 100 mg is the highest approved Viagra dose, but it’s not right for everyone. Learn about the side effects, risks, and who should consider a lower dose. Sildenafil (Viagra) is a prescription medication that is usually prescribed in 25 mg, 50 mg, or 100 mg doses. Exceeding the dosage of sildenafil prescribed by your healthcare provider or taking it more than once within a 24-hour period can be considered too much sildenafil. Take sildenafil at least 30 minutes, but no more than 4 hours, before sexual activity (1 hour before works best). This medication may take longer to start working if you take it with a high-fat meal. Do not take more than once daily as needed. For most people, the maximum recommended dosage of Viagra is 100 mg once per day. This dosage may be too high for people who have certain medical conditions or take certain medications. So it’s. Avoid taking Viagra more than once a day, since you should not exceed 100mg. If you experience any side effects, such as a painful erection or one that lasts more than 4 hours, vision less, chest pain, nausea, or irregular heartbeat, stop taking Viagra immediately and contact your doctor.