The generic name for Viagra is sildenafil, and an erection is not required while taking sildenafil for impotence. Sildenafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). The drug needs to be taken before sex, has a certain time limit, can improve the patient’s impotence condition, but if the patient does not have the need for sex, may not need to deliberately erection. It is contraindicated in patients who are allergic to sildenafil and those who are using nitrates. Common adverse reactions to the drug include headache, flushing, dizziness, nasal congestion, indigestion, and visual abnormalities. Patients are advised to seek medical attention in time and use the drug under the guidance of a doctor, avoiding private diagnosis and purchase for consumption. If adverse reactions occur, patients are advised to stop the drug in time.