Drug-induced movement disorders

Dopamine antagonists (eg antipsychotic drugs, metoclopramide, prochlorperazine) are the most common cause of iatrogenic movement disorders, especially in children. The effect of the drug can be acute (occurring immediately or soon after administering the drug) or tardive (resulting from chronic use and even persisting after stopping the drug).

The most common acute syndromes are acute dystonia (eg oculogyric crisis), acute akathisia and drug-induced parkinsonism. See definitions and management.

Classical tardive dyskinesia is the best known complication of long-term antipsychotic drug use, with a prevalence of around 20%. It is more likely to occur in elderly people, in females and with longer treatment. Tardive dystonia, another tardive syndrome characterised by more sustained movements with postural deformities, can be severe and even life-threatening. It can occur days to years after starting treatment with dopamine antagonists. Akathisia and tics can also occur as a tardive syndrome.

Treatment for established tardive syndromes is often ineffective, so prevention and early detection are important. Use dopamine antagonists at the lowest effective dose and regularly assess whether the patient needs continued treatment. While anticholinergic drugs are first-line treatment for generalised dystonia, no evidence supports their use for tardive syndromes.

When a tardive syndrome occurs in a patient who needs ongoing treatment for psychosis, seek expert advice.

Selective serotonin reuptake inhibitors can also induce abnormal movements.