Viagra generally refers to sildenafil citrate tablets, which are generally not recommended for normal use, and can be taken by those who meet the indications, ranging from 25 to 100mg per day, depending on their circumstances. Commonly used medications for the treatment of erectile dysfunction include sildenafil citrate tablets, which are generally recommended for dosage of 50mg/dose for most patients who meet the indications, and need to be increased to 100mg or reduced to 25mg depending on the user’s tolerance and the degree of efficacy of the medication, while taking it up to once a day; however, it is not recommended for use in normal people. The drug should be contraindicated in patients who are on guanylate cyclase agonists, nitrate drugs or who are allergic to one of the components of the product. Adverse reactions to the use of the drug include nasal congestion, headache, hot flashes, myalgia, back pain, dyspepsia, nausea, abnormal vision, rash, dizziness. The specific use of the drug in question should be under the supervision of a specialist.