The generic name of Viagra’s drug is sildenafil citrate, and no matter which pharmaceutical manufacturer produces this product, it is professionally certified before being marketed, and its efficacy is similar, so it is recommended that patients follow the doctor’s instructions for medication. Sildenafil belongs to phosphodiesterase type 5 and is mainly used clinically to treat erectile dysfunction. Regardless of which manufacturer produces this product, its efficacy is all tested and in line with national standards, and there is no significant difference. However, the drug is a prescription drug and should be applied strictly under the guidance of a doctor. Side effects that often occur with the use of sildenafil include nausea, rash, dizziness, headache, dyspepsia, back pain, myalgia, visual abnormalities, etc. It is contraindicated in patients who are allergic to sildenafil and the drug should not be used in combination with nitrate drugs.