Anticholinergic agents are the treatment of choice because they block cholinergic receptors and are thought to balance the cholinergic and dopaminergic activity: procyclidine 5-10mg IV/IM or benztropine 1-2mg IV/IM.

If the symptoms are truly an acute dystonic reaction, there should be improvement of symptoms within 5 minutes of IV administration and 20 minutes if given IM. Patients would be expected to be symptom free in 30 minutes.

A second dose can be given if there has been no response after 10 minutes IV (30 minutes IM). However, if there continues to be no improvement, an alternative diagnosis and cause should be sought.

Prophylaxis is required for 48 to 72 hours to prevent recurrence of symptoms: procyclidine 5mg TDS. In practice, patients are usually given prophylaxis for up to a week.

Benzodiazepines are GABA agonist; they inhibit and antagonise excitatory dopaminergic neurons. They can be helpful in refractory cases of dystonia:

diazepam 2.5-10mg IV

However, paradoxically there are reports of acute dystonic reactions occurring after administration of procyclidine and other anticholinergics.

Antihistamines with anticholinergic activity are an option if Procyclidine is not available. For example Promethazine IV or IM, 25-50mg.

Learning Bite

Dystonia can be treated with IM/IV anticholinergics (e.g. procyclidine) or antihistamines (e.g. promethazine). (Evidence Grade 3a).