Generally sildenafil efficacy lasts for about half an hour to four hours, but there is variability in the exact time due to different factors such as the patient’s body type, condition, and the drug manufacturer. Sildenafil is a type 5 phosphodiesterase inhibitor, mainly used to treat erectile dysfunction. According to relevant authoritative information, under normal circumstances, sildenafil efficacy can last about half an hour to four hours. However, the duration varies due to different factors such as each patient’s physical condition, the severity of the condition and the dose of the drug. The common contraindications of Sildenafil are women, children and so on. Secondly, some patients may experience adverse reactions such as fatigue, facial edema, abdominal pain, tachycardia, and vomiting after taking this drug. Patients must take Sildenafil under the guidance of a doctor, not without authorization, so as not to delay the condition and adversely affect the health.