A woman has died in Wellington after drinking GHB directly from a bottle without measuring her dose, as police investigate five suspected overdose incidents across the district.

Inspector Wade Jennings confirmed police attended five incidents involving suspected GHB overdoses, with one death. Three people remain hospitalised and one person was treated and discharged.

The incidents occurred across Wellington district including Miramar, Brooklyn, Johnsonville and Upper Hutt.

"An investigation is underway and police are treating the matter as a priority given the risk to the public," Jennings said. "If you, or someone you know, are feeling unwell, please go to your nearest healthcare provider urgently."

Details of the fatal overdose

The woman was staying at a castle-like mansion in the Wellington hills, a property previously called Woofingtons and now known as Wellington Castle.

Travis Mackay, who owns the property, said the woman had been staying with him there and had been using GHB for years while trying to stop.

Mackay said the woman had decreased her intake from 300ml across a four-day period down to 6ml daily. On the day she died, she was unable to find her usual measuring device and drank from the bottle without measuring.

"I thought she'd just gone to sleep," Mackay said. He said they attempted CPR after realising something was wrong.

"She was an amazingly happy woman, always smiling and joking around … She really was trying to get away from that life and that toxic crap," he said.

Potency and contamination concerns

Drug Foundation executive director Sarah Helm said the organisation has seen increased GHB use throughout New Zealand.

"They're very potent, very easy to overdose on," Helm said. She warned against consuming GHB with alcohol and other depressants.

Testing data shows 46% of GHB samples between January and March were not what users expected.

GHB is often referred to as fantasy or liquid ecstasy.

Property history

Police raided the Woofingtons property in 2019, resulting in one staff member receiving a community detention sentence for having black powder in a pyrotechnic device.