Spike in heroin overdoses in Perth

A spike in heroin overdoses in Perth has prompted St John Ambulance to issue a warning about drug use.

On average, there have been 46 patients each month this year, compared to 30 every month in 2012.

"It's a fatal habit and accidental overdoses can happen easily," Metro Ambulance Service general manager James Sherriff said.

"Unlike some other drugs, heroin can cause the user to stop breathing, their heart stops and they require immediate resuscitation if they are to have any chance of survival."

Mr Sherriff said anyone who found a heroin user overdosing should place them in the recovery position to minimise their risk of choking before calling triple zero.