Mirtazapine is an antidepressant and anxiolytic drug that usually takes 2-4 weeks to work. If the patient still does not see any effect after 2-4 weeks, the dose can be increased appropriately as prescribed by the doctor. If the dose of mirtazapine is increased to the maximum dose, and after 2-4 weeks, there is still no significant effect, then it can be considered that mirtazapine has no significant therapeutic effect on the patient. In conclusion, the onset of action of mirtazapine is usually 2-4 weeks, and there are individual differences in patients. Mirtazapine has a long metabolism time, with a half-life of 20-40 hours, so it is usually taken once daily. Because of its sedative effect, mirtazapine is generally recommended to be taken at bedtime, and once a day is usually sufficient to have a good therapeutic effect. The specific use of mirtazapine must follow the advice of the doctor. Mirtazapine also has certain side effects, as excessive sedation can cause drowsiness, lethargy, and in some cases, headache and dizziness. The more obvious side effects can cause weight gain or obesity, have a certain effect on blood glucose, which may cause blood glucose to rise, and can induce manic episodes in patients with bipolar disorder.