Depression or depressive disorders (Depression) is a persistent pessimism and lack of interest caused by a state of mind, a mental illness that seriously affects family, work, school, life, sleep and eating habits. Mood disorders include depression, bipolar disorder, alcohol or drug and other disease-induced mood disorders, etc. Depression mainly manifests as low mood, lack of interest, pessimism, slow thinking, lack of initiative, self-blame, poor eating and sleeping, worrying about suffering from various diseases, feeling unwell in many parts of the body, and in severe cases, suicidal thoughts and behaviors. Depression has become the fourth most disabling disease in the world, and according to the World Health Organization (WHO), by 2020, depression will become the second most disabling disease after cardiovascular disease, posing a serious public health risk. In the United States, 3.4% of depressed patients commit suicide, and 60% of those who commit suicide suffer from depression or other mood disorders. The diagnosis of depression is based on the patient’s complaints and what his or her family or friends tell him or her; laboratory or instrumental tests cannot diagnose depression. The age of onset of most depression is between 20 and 30 years, with a peak between 30 and 40 years and another age of onset between 50 and years. Depression is generally twice as common in women as in men, and urban residents have a higher incidence of depression than rural residents. Statistics from 2010 show that 4.3% of the world’s population suffers from depression, while the incidence of depression is 3% in Japan, 3 to 17% in the United States, and 8 to 12% in most countries, with major depression occurring in 3 to 5% of men and 8 to 12% of women in North American countries. Statistics show that the annual incidence of depression in China in 2012 was 5% to 10%. The etiology of depression is related to biological, psychological, and social factors, life events, environment, and drug and alcohol abuse, etc. Depression can be classified as atypical depression, stress depression, postpartum depression, menopausal depression, and seasonal affective disorder. The main treatments for depression are pharmacological, psychological and electroconvulsive therapy. depressed patients under 18 years of age are usually treated by psychological therapy, moderate and severe depression can be treated by psychological combined with pharmacological therapy, and electroconvulsive therapy can also be applied for severe depression. The main treatment for depression is antidepressant therapy, which should be applied continuously for at least 6 months to prevent recurrence of depression. Antidepressants mainly work by acting on neurotransmitters in the brain such as 5-hydroxytryptamine, norepinephrine or dopamine, and research shows that these neurotransmitters are related to the regulation of human mood. The main categories are as follows: 1, selective 5-hydroxytryptamine reuptake inhibitors: This class of antidepressants is widely used in recent years, mainly fluoxetine, paroxetine, sertraline, citalopram, fluvoxamine, escitalopram. These drugs are taken once a day, and the adverse effects are mainly gastrointestinal discomfort, sexual dysfunction, transient anxiety or sleep disturbance. These drugs have little effect on cardiac function, but citalopram has been reported to prolong the cardiac QT interval, and these drugs should be avoided in combination with monoamine oxidase inhibitors and should be used 2 to 4 weeks apart. Adolescent patients should be monitored for suicidal thoughts and behaviors when taking them. 2. 5-hydroxytryptamine and norepinephrine reuptake inhibitors: ? The mechanism of action of these drugs is to inhibit the reuptake of 5-hydroxytryptamine and norepinephrine to exert antidepressant effects. Adverse effects include decreased sleep, weight loss, dizziness, headache, nausea, vomiting, increased heart rate, increased blood pressure, and sexual dysfunction. Adolescent patients should pay attention to monitoring suicidal thoughts and behavior when taking. 3, tricyclic and tetracyclic antidepressants: tricyclic antidepressants are mainly promethazine, amitriptyline, clomipramine and doxepin. These drugs often cause dry mouth, constipation, blurred vision, urinary retention, cognitive or memory impairment and other anticholinergic adverse reactions, glaucoma, prostate enlargement and heart disease patients are prohibited. Tricyclic antidepressants and monoamine oxidase inhibitors should be avoided in combination, and should be applied 2 to 4 weeks apart. The main tetracyclic antidepressants are Maputtiline and Mianserin. 4, selective norepinephrine reuptake inhibitors; the main drug is reboxetine, the drug through the inhibition of neuronal presynaptic membrane norepinephrine reuptake, enhance the central nervous system norepinephrine function and play antidepressant effect, the drug can be tried in the treatment of panic disorder and attention deficit hyperactivity disorder, the drug in the United States is not approved for marketing applications. Reboxetine common adverse reactions include insomnia, nausea, excessive sweating, dry mouth, constipation, etc. It is prohibited in narrow-angle glaucoma, cardiovascular disease, epilepsy, bipolar disorder, urinary retention, prostatic hypertrophy and the application of monoamine oxidase inhibitors. 5, norepinephrine and dopamine reuptake inhibitors: its representative drug is bupropion, bupropion is adapted to the treatment of various types of depressive disorders, its selective 5-hydroxytryptamine reuptake inhibitors compared to sexual dysfunction and gastrointestinal discomfort caused by fewer side effects. 6, norepinephrine and specific 5-hydroxytryptamine antidepressants: the representative drug is mirtazapine, its main mechanism of action is to increase the central nervous norepinephrine and 5-hydroxytryptamine levels, strengthen the norepinephrine and 5-hydroxytryptaminergic nerve function, but also has a certain degree of antagonism to histamine H1 receptors, with anxiolytic and sedative effects, adverse effects mainly weight gain. 7, 5-hydroxytryptamine receptor antagonists and 5-hydroxytryptamine reuptake inhibitors: representative drugs for trazodone, is a 5-hydroxytryptamine enhancer, compared with other antidepressants, adverse reactions are less and light, anxiolytic effect is fast-acting, does not cause increased blood pressure, less likely to cause sexual dysfunction. 8, monoamine oxidase inhibitors: monoamine oxidase inhibitors are the first class of antidepressants used in clinical practice, mainly phenelzine, isocarbophosphate and morcobetamine, these drugs and tyramine-rich foods such as cheese, yeast, chicken liver, alcohol, as well as some analgesics, birth control pills, other antidepressants when combined can make the patient’s blood pressure rise, should be avoided, other side effects include insomnia, anxiety, weight gain and sexual dysfunction. Other side effects include insomnia, anxiety, weight gain and sexual performance disorders. 9, other antidepressants: including tianeptine, St. John’s wort extract, vilazodone and vortioxetine, etc. Tianeptine structurally belongs to the tricyclic antidepressants, but does not differ from the traditional tricyclic antidepressants, has a unique pharmacological effect, can increase the reuptake of presynaptic 5-HT, increase the storage of 5-HT in the vesicle and play the antidepressant effect, adverse effects are significantly lighter than the traditional tricyclic antidepressants, such as sedation, anticholinergic and cardiovascular system, less adverse effects, more common are dry mouth, constipation The more common ones include dry mouth, constipation, insomnia, dreaminess, dizziness, nausea, irritability and nervousness. St. John’s wort extract is a natural drug, its main active ingredient is chrysin, its pharmacological mechanism of action is complex, it has effects on central 5-hydroxytryptamine and norepinephrine, St. John’s wort extract has good efficacy on mild and moderate depression, with mild adverse effects, such as gastrointestinal reactions, dizziness, fatigue and sedation, but in clinical application, attention should be paid to photosensitivity reactions, St. John’s wort extract is used as a first-line antidepressant in European St. John’s wort extract is used as a first-line antidepressant in European countries. Vilazodone is a 5-hydroxytryptaminergic antidepressant approved for marketing in the United States in 2011. It increases central nervous 5-hydroxytryptaminergic activity by inhibiting 5-hydroxytryptamine reuptake, and common adverse effects include nausea, vomiting and constipation. The mechanism of action of vortioxetine is mainly related to the inhibition of 5-hydroxytryptamine reuptake and the enhancement of central nervous 5-hydroxytryptamine activity. Common adverse effects of vortioxetine include nausea, vomiting and constipation.