Warnings of dangerous drugs containing pesticides and industrial paint at Gisborne's Rhythm & Vines have been sent to festival-goers' phones today.
Tairāwhiti DHB announced on their Facebook page around 4pm that drugs seized from the Rhythm & Vines site "have been found to contain dangerous compounds such as pesticides and industrial paint compounds as well as other drugs including antibiotics and paracetamol".
It is understood the substances were found in fake MDMA tablets, which were discovered in a car by security.
An estimated 21,000 people are attending tonight for the finale of the four-day festival that started on December 28.
St John's head paramedic stationed at the Gisborne music festival, Shane Clapperton, said they had treated people for drug overdoses during the festival, but would not specify if these were reactions to the known dangerous drugs
The statement on Tairāwhiti DHB's Facebook page by Medical Officer of Health Dr Margot McLean advised that compounds found in the seized drugs could cause serious immediate and long-term health problems and should be avoided.
Anyone who feels unwell after taking drugs should seek medical attention.
Clapperton, said paramedics had already treated 700 people at the festival so far .
They were currently treating about 50 festival-goers per hour for a range of mainly minor issues - many of them heat-related.
"The last two nights have been busy for us, but 95 per cent of it is minor," Clapperton said, who has worked at all 16 Rhythm & Vines festivals.
"We've seen people who have overindulged in alcohol and drugs but we've been able to look after those people on site at our medical tent.
"We've probably been a little bit busier but a lot of it's minor."