Sildenafil generally refers to sildenafil citrate tablets, and the normal recommended dose for adults is 20mg at a time. The active ingredient in this product is sildenafil citrate, which is used in the treatment of pulmonary arterial hypertension in adults and is beneficial in improving exercise capacity as well as slowing the progression of the condition. In general, the recommended dose for adults is 20mg three times a day. If a dose is missed, a double dose at once should be avoided. For patients taking other medications, dosage adjustments should generally be made only after a risk assessment has been performed. There are many contraindications and adverse reactions, such as hypersensitivity to the active ingredients and excipients of the drug, severe liver damage, recent stroke or history of myocardial infarction, initial severe hypotension is prohibited, prohibit the combination with a variety of drugs, etc. Therefore, this product should only be used in the initiation of treatment and monitoring of the patient’s treatment by physicians experienced in the treatment of pulmonary arterial hypertension, and should not be self-administered.