Viagra is the trade name and the generic name is sildenafil citrate tablets. Taking one sildenafil citrate tablet will last for about 0.5 to 4 hours. The exact duration is somewhat related to an individual’s physical condition. Sildenafil citrate tablets are commonly used to treat erectile dysfunction. It usually needs to be taken within 0.5~4 hours before sexual intercourse. The duration after taking it is also within this range, and the exact duration is related to factors such as individual’s physical condition. When using Sildenafil Citrate tablets, sexual stimulation is necessary for it to work. The main common adverse effects of Sildenafil Citrate Tablet are headache, flushing, dizziness, nasal congestion, indigestion, and visual abnormalities. Sildenafil is forbidden to be used in combination with nitrate drugs, and the drug is contraindicated for women, people who are allergic to the product, children, and people whose recent cardiovascular status makes them unfit for sexual intercourse. Patients taking sildenafil citrate tablets should consult a doctor before using the drug, and take it under his guidance, do not take it blindly on your own.