Viagra is the trade name, the generic drug name is sildenafil citrate tablets, the method of eating is oral, the regular recommended dose is 50mg, need to be taken one hour before sex in advance. Sildenafil citrate tablets, mainly used for the treatment of sexual dysfunction, the regular recommended dose is 50mg, for patients with drug resistance, the oral dose can be adjusted between 25~100mg, and can be used up to once a day. Patients with reduced hepatic and renal function need to take a reduced dose, the specific time dosage needs to be used under the guidance of a doctor. Men during the use of sildenafil citrate tablets, if panic, chest tightness, dizziness, nausea, chest pain and other symptoms, should immediately stop sex, go to the hospital for timely medical treatment. Individual patients can also experience abnormal erection or long erection after taking the drug, which should be promptly consulted to avoid prolonged erection and excessive congestion of the penis, which can lead to damage to the penile tissues. Some patients need sildenafil citrate tablets to treat erectile dysfunction, it is recommended that patients use it according to medical advice under the guidance of a doctor, to avoid blind use or increase the dosage, resulting in adverse reactions.