Sildenafil is clinically used for the treatment of erectile dysfunction, Sildenafil can only be taken once in 24 hours and cannot be taken again after 8 hours. Sildenafil is a medication that is taken on an as-needed basis. Continuous use is not recommended as there are many adverse effects as well as the drug also has some toxicological effects. Common side effects of sildenafil include facial flushing, muscle pain, fatigue, and headache, which can usually be relieved quickly, and most of the relief does not affect the next dose of the drug. If there is no relief for a long time or heart symptoms such as angina occur, seek medical attention and do not take sildenafil again. It is contraindicated in patients who are allergic to any of the ingredients in this product. Sildenafil can enhance the antihypertensive effect of nitrate. Therefore, it is contraindicated in patients taking any dosage form of nitrate, either regularly or intermittently. Sildenafil is not indicated for use in women. In summary, patients are advised to closely monitor the extent and duration of side effects and to seek medical attention and specialist help for any such abnormalities.