Sildenafil is a drug used for the treatment of penile erectile dysfunction, and clinical practice has confirmed that it works well when used rationally under the guidance of a physician. Sildenafil is a first-generation type V phosphodiesterase inhibitor that increases blood flow in the intracavernous arteries of the penis to produce an erection. It is rapidly absorbed after oral administration and takes effect in 10-40 minutes. Food can have an effect on absorption and needs to be taken on an empty stomach. The effect lasts about four hours with good erection hardness. Also, note that sildenafil needs to be taken with sexual stimulation in order to work properly, and the maximum daily dosing frequency is once. If side effects occur during the course of the medication, the medication should be stopped immediately and the symptoms will disappear slowly after 6-8 hours. This drug is a prescription drug and must be used under the guidance of a doctor, please follow the medical advice.