A drug harm reduction advocate says an "early warning system" needs to be set up to prevent drug harm in New Zealand.

It comes after 13 people were hospitalised in Christchurch after taking a drug falsely sold as ecstasy.

The pills were later found to be N-Ethylpentylone - a drug three times stronger than ecstasy.

Wendy Allison is director of Know Your Stuff - a group that lets people test their drugs at music festivals.

She put out an alert about N-Ethylpentylone three weeks before the mass hospitalisation.

She told Mike Hosking that this incident is just the latest in her experience, and says it is not surprising that this happens. 

"In an illicit market, dishonest is rewarded and there is no quality control and no comeback for product misrepresented as an other product."

She says having an early warning system would help inform the public about new, dangerous substances as soon as possible. When people find our their drugs aren't what they're supposed to be, most people don't take them.

The system would see coroners, pathologists, emergency departments and St John share drug information.

Allison also believes that the government needs to support initiatives that allow people to test their drugs to avoid similar outcomes to what happened in Christchurch.

LISTEN TO WENDY ALLISON TALK WITH MIKE HOSKING ABOVE