Viagra (sildenafil) is a highly-efficient medication specially designed for the treatment of erectile dysfunction, also known as ED. This condition can occur in men as young as twenty, which is why Viagra is getting more and more popular these days. It’s important to take this medicine exactly as prescribed. Before you will be given your prescription, your health care provider will probably want to know if there are any medical conditions that may potentially interfere with the success of your treatment. The following ones are important to be mentioned: penis conditions, blood system cancers, coronary artery disease, kidney disease, eye problems, bleeding disorders, active stomach ulcers, recent stroke, heart failure, recent heart attack, very high or low blood pressure, liver disease, and sickle cell anemia. Viagra is not likely to cause any side effects that re serious, but some side effects are still possible. The following ones are common at the beginning of the treatment: color vision problems, headaches, diarrhea, nasal congestion, facial flushing, nausea, and stomach pain. In case you are also taking medications for impotence, rifamycins, azole antifungals, alpha-blocker medications, HIV protease inhibitors, mibefradil, cimetidine, erythromycin, or high blood pressure medicines, tell you doctor in advance to exclude the possibility of drug interactions.