A dangerous stimulant is being sold as MDMA in Christchurch, drug testing organisation High Alert has warned.

High Alert said the stimulant is an Alpha-PVP like substance and has been detected in a brown powder presumed to be MDMA.

They said festival-goers are urged to take “extreme caution, and testing is recommended to help minimise risk.

“Drug checking services can identify when a substance is not what it has been sold as.

“If you or someone you know takes a substance thought to be MDMA and starts to feel unusual effects, call 111. Be honest about your drug use. It could save your life.

“People who consume this powder believing it to be MDMA are at risk of experiencing adverse effects and serious harm because Alpha-PVP and similar substances are more potent than MDMA, and they may inadvertently take multiple doses.

“The powder is believed to be widely circulating in the Christchurch region and may possibly be present in other regions.”

The High Alert website says the concern is people may already have the substance thinking its MDMA.

“It is important to never assume that what you have is the same as what you are being told it is. Misrepresentation can occur anywhere along the supply chain.”

It comes after the Hidden Lakes festival in Christchurch kicked off last night, with thousands of punters rolling in ahead of New Years Eve.