Viagra is the trade name and generic name of Sildenafil Citrate Tablets. The effectiveness of Sildenafil Citrate Tablets lasts for about 0.5 to 4 hours. Sildenafil citrate tablets are suitable for the treatment of male erectile dysfunction, generally recommended that patients take sildenafil citrate tablets on demand about 1 hour before sexual activity, the drug effect generally lasts for about 0.5~4 hours, the specific duration is related to the patient’s personal constitution and other factors. Common adverse reactions to Sildenafil Citrate Tablets include dizziness, lightheadedness, hypotension, and abnormal ejaculation. Sildenafil Citrate Tablet is contraindicated for patients who are taking nitrate drugs, such as nitroglycerin and sodium nitroprusside. In addition, it is contraindicated for patients who are allergic to Sildenafil Citrate or any of the excipients. Sildenafil citrate tablets must be used in accordance with medical advice, before using the drug need to consult a professional physician or pharmacist, if you are taking antihypertensive drugs or nitric acid and other drugs need to inform the physician or pharmacist, in order to avoid adverse consequences.