Serotonin syndrome secondary to tramadol and citalopram

A 78-year-old lady, on citalopram, presented with confusion after a recent fall and commencement of tramadol for pain. Initial examination was unremarkable, routine bloods were normal and an urgent CT brain scan excluded haemorrhage. Subsequent examination after further deterioration revealed tachycardia, global myoclonus, increased tone, hyperreflexia and bilateral upgoing plantars. Serotonin syndrome secondary to tramadol, in combination with the selective serotonin re-uptake inhibitor citalopram, was suspected. Revision of her history, a lumbar puncture, an EEG and serum creatine kinase excluded alternative diagnoses. Symptoms resolved completely on discontinuation of both drugs. Serotonin syndrome is an under-recognised disorder of excessive serotonergic activity [1]. It can be caused by a number of pro-serotonergic drugs used in everyday clinical practice in older adults [2]. The risk of toxicity increases with co-prescription of culprit drugs. A high degree of clinical suspicion is needed to make the diagnosis which, if missed, can be fatal.