Sildenafil is taken on an as-needed basis for the treatment of erectile dysfunction, there is no set frequency of use, but it can be taken up to once a day, some doctors may recommend taking the medication once a day, as prescribed by your doctor. It may be taken daily for the treatment of pulmonary arterial hypertension, but should be taken as directed by your doctor. Sildenafil is mainly used to treat erectile dysfunction, and for most patients, it is best to take it as needed about one hour before sexual activity, but it can be taken anytime from half an hour to four hours before sex, up to once a day, and sildenafil does not work without sexual stimulation. When used to treat erectile dysfunction, some doctors will recommend that patients take sildenafil regularly (once a day), but not every doctor will so recommend, the drug instruction manual does not have the corresponding dosage, if the doctor recommends regular use, follow the doctor’s instructions. Sildenafil can also be used to treat pulmonary arterial hypertension, when it can be taken daily, the dosage and frequency of the drug varies among different groups of people, and should be followed by the doctor’s instructions. After taking this product, patients may experience hypotension, chest pain, migraine, palpitations, atrioventricular block, palpitations, premature ejaculation, urinary frequency, vision loss, tinnitus, conjunctivitis, headache, nasal congestion, rash, dyspepsia, and other adverse reactions, the use of organic nitrites, patients allergic to the product, patients using guanylate cyclase stimulant patients prohibited this product. It is recommended that patients who are unwell go to a regular hospital in time and follow the doctor’s instructions for medication.