ENERGY drinks may be interfering with anti-psychotic medication in schizophrenia patients and causing them to relapse.

Writing in the latest Medical Journal of Australia, psychiatrist David Menkes describes the case of a 27-year-old man with schizophrenia who had two separate psychotic events a week apart after consuming Demon Energy Shots.

Demon Shots, widely available in Australia and New Zealand in 60ml bottles, contain 200mg of caffeine, plus other ingredients which may have stimulant properties.

"Although case reports and a later controlled study suggest that high doses of caffeine may exacerbate psychosis, this has only recently been observed with energy drinks," said Associate Professor Menkes, of the University of Auckland.

"This case provides evidence that some patients with treated schizophrenia may be vulnerable to exacerbation of their illness by caffeine-containing energy drinks."

Professor Menkes said he suspected the caffeine in the drinks was reversing the effects of anti-psychotic medication which blocked the brain chemical, dopamine.

"Caffeine promotes the release of dopamine," he said.

He's called for more research into the problem.

"People with psychotic illnesses should be aware of the risk, which probably varies from person to person," Professor Menkes said.

Originally published as Energy drinks "exacerbate'' psychosis