Treatment of OCD is tricky, treatment is poor, and outcomes are often unsatisfactory. The treatment effect is better for those whose compulsions are dominant. OCD is slow to take effect, its efficacy is calculated on a monthly basis, a dose needs to be observed for more than a month to see the efficacy, the efficacy of OCD is often incomplete, not completely cured, it is recommended to take medication for life to maintain the efficacy, some patients stop medication relapse after re-treatment more difficult to see the effect. Any drug that blocks 5-HT2 receptors may lead to OCD. Medications that increase 5-HT in the synaptic gap are capable of treating OCD. OCD, including OCD induced by antipsychotics, is treated in the same way (in the case of OCD induced by the psychotropic drug clozapine, the drug clozapine needs to be stopped first and replaced by haloperidol or pentoxifylline, which have no effect on 5-HT receptors, otherwise it will not be very effective). Clomipramine 150mg to 250mg per day may be effective, but the drug has significant side effects, takes at least 2 months for symptoms to improve, and is 70% effective. Excessive doses may even cause toxicity. Because of its side effects, its use is limited. A commonly used drug for OCD is the SSRI. Several drugs have similar efficacy for OCD, and adequate doses are the key to treatment. To treat OCD, fluoxetine is often twice as much as the amount of medication used for depression. For the treatment of OCD, fluoxetine 40 mg/day is usually needed, and a few patients need fluoxetine 60 mg/day or more. If fluoxetine alone does not work, clomipramine may be used, but at most 50 to 75 mg. clinically potent, 20 mg fluoxetine, is equivalent to 20 mg paroxetine (or 75-100 mg sertraline, or 150-200 mg fluvoxamine, or 30-40 mg citalopram, or 10-20 mg escitalopram). If other SSRI drugs are applied, the dose can be referred to fluoxetine dose. Other antidepressants, as long as they can block the recycling of 5-HT, also have more or less anti-compulsive effects. However, mirtazapine may induce obsessive-compulsive disorder (because it also blocks 5-HT2 receptors), so it should not be used to treat OCD.