Viagra is a drug used for the treatment of male penile erectile dysfunction. The effect of Viagra can last for 4 hours and can improve sexual performance very well, but the specific effect still varies from person to person and has a certain relationship with the patient’s basic sexual life and erectile status, in addition to promoting erection, it can also properly prolong the duration of sexual life. It is generally recommended to be taken 1 hour before sex to have a better therapeutic effect. The efficacy of Viagra has been shown to last for 4 hours, but it usually has a better therapeutic effect in the first 2 hours and a weaker effect in the next 2 hours, which is related to the metabolism time of the drug in the body. Generally, after oral administration, the blood concentration of the drug reaches its peak in half an hour to 2 hours, and for most patients, the time when the blood concentration reaches its peak is 1 hour, so it is recommended that patients take it 1 hour before sex, so that it can play a better therapeutic effect. Viagra may cause side effects such as heartburn, flushing, and heart burden in those who take it, so it is recommended not to take the drug on your own, but under the guidance of a professional doctor.