What is Viagra? Viagra is a brand-name prescription drug that’s approved to treat erectile dysfunction (ED). With ED, you’re unable to have or maintain an erection. Viagra is .It continues to work for up to 4 hours, although its action is usually less after 2 hours. When choosing one, tell your doctor or other health care professional what your preferences are, such as cost, ease of use, how long the drug’s effects last and side effects. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. About sildenafil Viagra Sildenafil is a medicine used to treat erection problems erectile dysfunction. If you experience a sudden loss of vision in one or both eyes, contact your doctor immediately. Children younger than 1 year of age—Use and dose must be determined by your doctor. Remove the cap by pushing it down and twisting it counter-clockwise.Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial . Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in adult males* with . What is Viagra? Viagra relaxes muscles found in the walls of blood vessels and increases blood flow to particular areas of the body. Viagra is used to treat erectile dysfunction .Your doctor may adjust your dose as needed and tolerated. The following information includes only the average doses of this medicine. Oral medicine for ED also might not be safe or work well if you have: Very low blood pressure, called hypotension, or uncontrolled high blood pressure, called hypertension. It can be dangerous to take sildenafil if you also take medicines called nitrates often given for chest pain. Check with your doctor right away if you have a sudden decrease in hearing or loss of hearing, which may be accompanied by dizziness and ringing in the ears. Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. The most common side effects are headaches, feeling sick, indigestion and dizziness.