[An anticholinergic syndrome with hallucinatory psychosis after diphenhydramine poisoning]

A 27-year-old female student was hospitalized as an emergency because of gait and speech disorders which had developed over just a few hours. Conflicts with her partner and frequent alcohol abuse were reported. It was not possible to interview the patient herself. Consciousness was clouded by optical and acoustic hallucination. Body temperature was 38.1 degrees C: the skin was warm and dry, the tongue dry. Heart rate was 120/min, blood pressure 150/100 mm Hg. Neck and limb muscle tone was increased. Hallucinatory psychosis, encephalitis and alcohol withdrawal delirium were considered in the differential diagnosis.

There was hypokalaemia, slightly increased serum creatinine and metabolic alkalosis. The alcohol level was 0.18%. The ECG was normal except for sinus tachycardia.

In the meantime, two empty packets of 20 tablets each had been found in the patient's flat. They had contained Vivinox and Sediat (total of 1.5 g diphenhydramine), so that a central anticholinergic syndrome due to an overdose with this drug could be assumed. The diphenhydramine level was 2.8 micrograms/ml. After administration of altogether four times 2 mg physostigmine and 5 mg diazepam intravenously and normalization of electrolytes the symptoms regressed within 12 hours. The patient then admitted to having taken the drugs with suicidal intent. She was transferred to the psychiatric department because of the risk of further suicidal attempts.