Viagra generally refers to sildenafil citrate tablets, regardless of which manufacturer produces, its side effects are similar, including dizziness, headache, visual abnormalities, etc. Patients are advised to follow the doctor’s instructions to standardize the use of medication. Sildenafil citrate tablets can increase the blood flow to the cavernous body of the penis in men, and are clinically used in the treatment of male erectile dysfunction. Regardless of which manufacturer produces this product its side effects are similar, there is no significant difference, its commonly occurring side effects are visual abnormalities, dizziness, headache, rash, back pain, myalgia, nasal congestion, nausea, dyspepsia and so on. It is contraindicated in patients with known hypersensitivity to the product and in patients taking nitrates. It is recommended to consult a physician before using the drug and should not be used blindly.