Delayed dyskinesia is divided into the following types according to the site of dyskinesia ① abnormal eye muscle movement: blinking, blepharospasm, etc.; ② abnormal facial muscle movement: facial muscle twitching, jerking and sad face, etc.; ③ abnormal mouth muscle movement: pouting, smacking, chewing, suction and lateral jaw movement, etc.; ④ abnormal tongue muscle movement: tongue extension, tongue contraction, wriggling and lip licking, etc.; ⑤ abnormal pharyngeal muscle movement: abnormal palate movement affecting pronunciation and (6) abnormal neck movement: slanting neck, backward neck, etc.; (7) abnormal trunk movement: uncoordinated trunk movement, odd posture, such as shrugging shoulders and retracting back, corkscrew, twisting spasm, diaphragm spasm producing grunting and breathing difficulties, sometimes the whole body swaying from side to side, repeated trunk flexion and extension, back and forth twisting, called body shaking sign; (8) abnormal limb movement: continuous flexion and extension of the distal limbs, called playing piano fingers (toes) sign. The proximal end is rarely involved, and a few of them show dance-like finger paddling movements, throwing movements, hand and foot squirming-like movements, repeatedly raising the hands or jumping on both legs. How to check for delayed dyskinesia? It occurs mostly in elderly patients, especially in women, with organic brain lesions, with heavy symptoms and slow recovery. It can be caused by various antipsychotic drugs, and is common with fluorine-containing antipsychotics such as fluphenazine, trifluoperazine and haloperidol, and mostly occurs after taking antipsychotics for more than 1 to 2 years, with the shortest period of 3 to 6 months and the longest period of 13 years. The main clinical manifestations are rhythmic stereotyped repetitive involuntary movements, early manifestations of tongue tremor or salivation, characteristic mouth movements in the elderly, and common limb involvement in younger patients. In children, the orofacial symptoms are more prominent, and the lower muscles are most often involved, showing the mouth-tongue-buccal triad (BLM syndrome) or cheek, tongue and mastication syndrome, showing repetitive and uncontrollable movements of the lips and tongue, such as involuntary continuous stereotyped chewing, sucking, tongue turning, tongue licking, pouting and cheek puffing, crooked jaw and neck turning, sometimes the tongue suddenly sticks out of the mouth involuntarily, called flytrap tongue sign, and in severe cases, slurred diction In severe cases, there is slurred speech and swallowing disorder. The involvement of trunk muscles shows body shaking, the involvement of distal limbs shows piano finger (toe) sign, the proximal limbs are rarely involved, a few show dance-like movements, aimless flapping, legs jumping, hand and foot twitching, twisting trunk movements and odd postures. Occasionally, the gastrointestinal tract is affected, with stomach discomfort, nausea and vomiting occurring after sudden discontinuation of the drug. The symptoms are aggravated by emotional stress and excitement and disappear during sleep. Some patients coexist with delayed sedentary inability, delayed dystonia, and pharmacogenic Parkinson’s syndrome, and symptoms are easily masked and exposed when the drug is reduced or discontinued. The first priority is to avoid risk factors. Clinicians should adhere to the following principle: only patients who really need the application of antipsychotics (e.g., schizophrenia) should be given them. Antipsychotics should never be used to treat neurosis or depression, much less as a sleeping pill for insomnia. This is because the onset of delayed movement disorder is not related to the size of the drug dose, and can occur even in small amounts. If delayed-onset dyskinesia occurs in a patient with schizophrenia, it should be weighed against the severity of the problem and should not be discontinued hastily.