SSRIs, also known as 5-hydroxytryptamine reuptake inhibitors, are the most widely used and the earliest of the new antidepressants, of which there are about six in clinical practice, including citalopram, escitalopram, sertraline, paroxetine, fluvoxamine and fluoxetine. The mechanism of action is to increase the concentration of 5-hydroxytryptamine in the synaptic gap, thus increasing the reuptake of 5-hydroxytryptamine in the postsynaptic membrane, thus achieving the antidepressant effect. Compared with the original first class antidepressants, the effect of these drugs is smaller, especially the sedative effect is smaller, at the same time, it is also more convenient to take, as long as one meal per day can be taken, the effect of these drugs is relatively strong, may take 1-2 tablets can play a very good antidepressant effect, in the clinical application more and more widely, but there are also some restrictions, individual patients, especially adolescents in the In the early stages of using these drugs, the sudden increase of 5-hydroxytryptamine in the postsynaptic membrane leads to irritability and an increased risk of impulsivity and suicide. It is recommended that these drugs be used under medical supervision and with caution.