New critical care teams stationed at Sydney music festivals may have stopped several people from dying or receiving serious injuries, health officials say.

Three revellers are fighting for life and eight others remain in hospital after a series of suspected drug overdoses at music festivals in Victoria and NSW at the weekend.

While three men aged in their 20s are in a critical condition after apparent overdoses at the Rainbow Serpent Festival near Ballarat in Victoria, NSW health officials believe $500,000 worth of increased medical support saved lives at three Sydney events.

A 20-year-old man was taken off life support in Sydney on Monday after 25 people - aged between 16 and 67 - left the Hardcore Till I Die, Rolling Loud and Electric Gardens events on Saturday and Sunday in an ambulance.

NSW Health said five people were still in hospital on Monday afternoon and that drugs were likely a factor in 15 of the cases.

Six people thought to have overdosed at the Rainbow Serpent Festival remain in hospital, including the three critical men.

Paramedics in NSW believe new teams of critical care medical staff at the Sydney festivals were the reason nobody died.

Sarah Coombes from NSW Ambulance said some drug-affected patients were agitated, delirious and had extremely high temperatures, which can "effectively cook" their organs and muscles.

"A number of patients were treated that likely would not have survived had the increased medical support not been on site - or, if they did survive, would not have survived neurologically intact," she told reporters on Monday.

Dr Coombes said early intervention meant people didn't need to wait until they arrived at hospital for live-saving treatment.

"By aggressively sedating to control the patient and then doing the life support measures necessary, we were able to control the amount of work the body is doing ... and then aggressively reduce the body temperature."

The NSW government spent about $500,000 over 10 days on harm reduction measures for the three festivals, including on the critical care teams, roving drug educators and free electrolyte drinks.

Health Minister Brad Hazzard plans to introduce legislation to force festivals held from March to foot the bill for the extra measures.

But he again ruled out supporting pill testing which is backed by several leading medical associations.

Mr Hazzard called pill testing a "sideshow" while Premier Gladys Berejiklian said she didn't want the culture of people thinking it was okay to take ecstasy.

"It is not acceptable to take ecstasy and think it is not going to affect you, your friends or your loved ones," the premier told reporters.

Nine people across the Sydney festivals were charged with drug supply, including two 17-year-olds, one of whom allegedly had 579 capsules and $2075 on him.

Some 84 people, mostly from the Electric Gardens event, were charged with drug possession while about 26 others were given cautions or on-the-spot fines.

Victoria Police caught 13 people with drugs, and arrested three men for a range of offences including drug trafficking and possessing proceeds of crime.