Psychiatric co-morbidity associated with pheniramine abuse and dependence

The abuse of cough syrups containing antihistamines and codeine is being increasingly noted. The abuse of antihistamines alone has also been reported. The use of antihistamines alone or in combination with other substances of abuse may predispose individuals to develop psychiatric symptoms or syndromes as a part of intoxication, withdrawal or as co-morbid conditions. We present two case reports to highlight the occurrence of co-morbid psychopathology in association with antihistamine abuse and dependence. Case I used high doses of pheniramine for about 2 years and became suspicious of his wife; he even doubted the paternity of his yet-to-be-born child. The associated behavioural abnormalities suggested that he was acting out on the delusion. He also had seizures associated with the intake of a high dose of pheniramine. Case II had multiple substance use, and dependence on alcohol and pheniramine. He demonstrated abnormal behaviour suggestive of psychosis and organic brain syndrome that persisted for a few days and remitted on discontinuation of the substances. These two cases demonstrate the occurrence of psychotic syndromes associated with heavy pheniramine use. The psychopathology can vary from an independent psychotic syndrome to an organic brain syndrome-like disorder.