Viagra (sildenafil) is the world’s most popular medicine used for the treatment of male impotence. It is available online and can be purchased without prescription, but it’s very important to make sure you do need to be taking Viagra for your condition. In case you are also taking nitrates, isosorbide dinitrate, or isosorbide mononitrate it’s not recommended to take Viagra as this may lead to a sudden drop of blood pressure, which may result in fainting, stroke, or a heart attack. Viagra is available by a prescription and comes in diamond-shaped blue tablets of 25 mg, 50 mg, and 100 mg. The symptoms of an overdose include nausea, irregular heartbeat, fainting or lightheadedness. Avoid using more of Viagra than prescribed by your health care provider, as this can lead to serious health effects. According to one of the studies in some rare cases sildenafil (Viagra’s active compound) may lead to vision impairment, sudden loss of hearing, stroke, intraocular pressure, heart attack and hypotension. However, it was also found that people with a number of risk factors may be more prone to this symptom – those that smoke regularly, are older than 50 or have some health problems, such as diabetes, high blood pressure, high cholesterol etc. Priapism is an erection that lasts longer than 4 hours and is usually painful. This side effect may lead to a permanent damage of the penis, which is why it is recommended to seek immediate medical help if you notice the signs of priapism. Patients with a history of priapism are at a higher risk of developing this condition and they may need to abstain from taking Viagra at all due to that. Other serious side effects that are possible can be irregular heartbeat, sudden vision loss, shortness of breath, ringing in your ears, vision changes, feeling light-headed, chest pain, sudden hearing loss, sweating, nausea, general ill feeling, and swelling in your hands. Any of the side effects mentioned are supposed to be reported to your health care provider as soon as possible to prevent them from getting worse. To make sure the initial dose of Viagra is safe and efficient for you, report to your health care provider any health problems you have, as some of them can lower the effectiveness of Viagra while others can be risk factors for developing serious side effects. The following medical conditions are supposed to be reported to your health care provider before you start the treatment: heart attack, pulmonary veno-occlusive disease, heart disease, blood circulation problems, kidney disease, stomach ulcer, blood cell problems, bleeding disorder, stroke, high cholesterol, liver disease, diabetes, conditions affecting the shape of the penis, irregular heartbeat, high or low blood pressure, and chest pain. If you think Viagra is not working properly for you, talk to your health care provider, but never alter the dose based on your own judgment. Taking more of this medicine is not going to make your treatment more efficient or cure your erection.