Discover the mild and serious side effects of Viagra (sildenafil). Learn how to manage symptoms safely and when to seek medical help. Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. 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. Learn about the side effects of Viagra (sildenafil), from common to rare, for consumers and healthcare professionals. Viagra is a phosphodiesterase 5 (PDE5) inhibitor. It works by causing more blood to flow to the penis for an erection. This can be beneficial for ED. But it can also cause side effects, such as headaches, flushing, and upset stomach. Serious side effects are rare, but they can happen too. “The little blue pill” known as Viagra is the world’s most popular erectile dysfunction medicine. It’s also the source of many inaccurate medical myths. Viagra (sildenafil) is a brand-name prescription drug that’s used to treat erectile dysfunction (ED). Learn about side effects, warnings, dosage, and more. 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 (impotence) in men. Learn which Viagra side effects are common and harmless, which ones need medical attention, and how your dose and health history affect your risk. This article breaks down eight common and serious side effects of Sildenafil, how to manage them, and when to seek medical help. One of the most frequently reported side effects of Sildenafil is a headache, which occurs in a significant number of users.