Hippocampal ischaemia from accidental 5-Hydroxytryptophan (5-HTP) overdose case report.

We report severe reversible hippocampal ischaemia following an accidental 5-Hydroxytryptophan (5-HTP) overdose. Serious consequences from 5-HTP overdose have not been reported. A 44-year-old previously well man ingested ten times the recommended dose of 5-HTP powder. After four hours he developed marked antegrade and retrograde amnesia, disorientation and confusion in the absence of loss of consciousness, seizure activity or features of serotonin toxicity. Magnetic resonance imaging (MRI) of the brain on day two revealed extensive symmetrical restricted diffusion bilaterally in the hippocampi, suggestive of ischaemia or seizure. Electroencephalogram was normal. Short and long-term memory improved sufficiently to return to work after two months. MRI at eleven months was normal. The most likely mechanism is drug-induced hippocampal ischaemia resulting from marked increase in 5-HTP.