Promethazine, 25-50 mg intravenously or intramuscularly, has been used less frequently but it works and it is readily available in most emergency departments and doctors' bags. Popular American texts 2, 3 recommend diphenhydramine 1-2 mg/kg up to 100 mg by slow intravenous injection, and the current Oxford Handbook of Clinical Medicine 4 suggests procyclidine, but neither of these drugs is available in Australia as a parenteral preparation. If there is no response the dose can be repeated after 10 minutes, but if that does not work then the diagnosis is probably wrong. Most patients respond within 5 minutes and are symptom-free by 15 minutes. Trunk muscles and less commonly limbs can be affectedĭystonia responds promptly to the anticholinergic benztropine 1-2 mg by slow intravenous injection. May be accompanied by trismus, risus sardonicus, dysarthria and grimacing The tongue does not swell, but it protrudes and feels swollen When severe the back is involved and the patient arches off the bed. Spasm of the extraorbital muscles, causing upwards and outwards deviation of the eyes Manifestations of acute dystonia Oculogyric crisis If there is any doubt, it is reasonable to treat as an acute dystonic reaction in the first instance, and investigate further if there is no response.