Sildenafil citrate is a western drug used to improve erectile dysfunction and is a selective type 5 phosphodiesterase inhibitor, which can quickly fill up the penile body within a certain period of time to achieve an erection and hard enough to play a supplementary therapeutic role. The drug is usually taken about an hour before sexual intercourse, and requires sexual stimulation before it can take effect, and lasts about 4-6 hours. However, older patients and patients with cardiovascular disease need to be cautious about using it, as dizziness, nausea, headache and even fainting may occur in severe cases. In addition, if the erectile function of the penis is examined by the hospital and is caused by other diseases, such as chronic prostatitis and so on, then you cannot take sildenafil citrate, you need to resolve the original disease first and see the recovery before deciding.