Psychosis linked to Vic synthetic cannabis

Victorians looking to get high have been warned to steer clear of a new batch of "toxic" synthetic cannabis after 20 people were hospitalised in a psychotic state.

The Alcohol and Drug Foundation issued a warning to health professionals after two major Melbourne hospitals reported a spike in patients presenting with psychosis in recent weeks.

Those affected had reportedly taken Blue Lotus, a synthetic cannabis marketed as a herbal drug.

ADF program manager Julie Rae says users often underestimate the toxic effects of synthetic drugs.

Cannabis normally depresses the nervous system but synthetic drugs like Blue Lotus often over-stimulate the body.

That over-stimulation could result in symptoms similar to ice-induced psychosis.

"Nobody knows what is in these concoctions, they are toxic," Ms Rae told AAP on Friday.

Synthetic cannabis can also be known as Kronic, Northern Lights, Mojo, Lightning Gold and Godfather.

It can be smoked or drunk as tea and can cause irregular heartbeat, racing thoughts, anxiety, psychosis, violent behaviour and even death.

The Victorian health department warns the sale of synthetic drugs is illegal.