How long to take sildenafil citrate needs to be based on the patient’s condition, and can not be generalized, it is recommended to follow the doctor’s instructions for medication. The drug can be stopped when the symptoms disappear in the treatment of erectile dysfunction; the treatment of pulmonary arterial hypertension usually requires long-term use. Sildenafil citrate tablets are commonly used in the treatment of erectile dysfunction, the course of treatment depends on the patient’s own condition, and can be discontinued after the disappearance of symptoms. In clinical practice, the drug can also be used to treat pulmonary arterial hypertension (PAH, WHO group 1) in adults, which can improve exercise capacity and delay clinical deterioration, at which point the patient may need long-term medication. The exact duration of dosing also needs to take into account the patient’s tolerance as well as toxic reactions, so the course of treatment varies from patient to patient and should be strictly followed. After using the drug, patients may have headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness, rash and other adverse reactions. It is contraindicated for those who are allergic to the drug and should not be used by pregnant women. The drug should be applied under medical supervision.