Viagra is the trade name, the generic name is sildenafil, the effect of taking a capsule of sildenafil at the age of 30 also varies from person to person, and can usually last for 4 hours. However, if the sex life is not lasting caused by premature ejaculation, the drug does not have a therapeutic effect, and premature ejaculation is applied to drugs such as Dapoxetine. Sildenafil is mainly used to treat erectile dysfunction. After the drug is taken, a good erection can usually be maintained within 0.5 to 4 hours, and the erection will disappear after sex is over. However, if the sexual life is not lasting because of premature ejaculation, the use of this drug is not therapeutic effect, at this time, you can apply Dapoxetine and other drugs for treatment. Common adverse reactions to the use of the drug are mainly headache, flushing, dizziness, nasal congestion, indigestion, visual abnormalities and so on. Sildenafil is forbidden to be combined with nitrate drugs, this drug is contraindicated for women, people who are allergic to this product, children, and people whose recent cardiovascular state does not allow them to have sex. Sildenafil is not recommended for long-term use, and it is recommended to go to the hospital for a detailed examination to clarify the cause of the disease and then treat it, so as not to cause damage to the body. The drug should be applied under medical supervision.