Priligy is the trade name, the main ingredients are sildenafil and dapoxetine; and Viagra is the trade name of sildenafil, the main ingredient is sildenafil, so the difference between the two lies in the effect of dapoxetine and the adverse reactions, the former adverse reactions appear more probable. Sildenafil is mainly used for the treatment of erectile dysfunction, can be used for people who can not get an erection, the use of general can appear postural hypotension, abdominal pain, diarrhea, nausea and other adverse reactions. And it is contraindicated in people who have recently or are using nitrates, guanylate cyclase stimulators and people who are allergic to sildenafil. Dapoxetine is mainly used to treat people with poor ejaculatory control and premature ejaculation. Adverse effects such as anxiety, abdominal pain, diarrhea, and hypotension can occur with its use. It is contraindicated in people who are allergic to dapoxetine or have severe pathologic heart disease, as well as people with a history of mania or major depression, recent use of monoamine oxidase inhibitors, thioridazine, serum reuptake inhibitors, potent cyp3a4 inhibitors, and people with moderate to severe liver damage.