More than 30 people have been hospitalised after attending separate music festivals in Sydney and regional Victoria, with three still fighting for life after suspected drug overdoses.

At least 25 people aged between 16 and 25 were hospitalised on Saturday and Sunday following three events across Sydney, and more than half of them needed to be treated on site by critical care medical teams.

“I believe six of those … had tubes down their throat to assist their breathing,” NSW Health Minister Brad Hazzard told reporters in Sydney on Monday.

“There would have been parents, mums, dads, other family and friends wondering whether they would come home from those music festivals.”

The medical crews were deployed by the NSW government to the Hardcore Til I Die, Rolling Loud and Electric Gardens festivals as part of a range of extra safety measures.

Sarah Coombes from NSW Ambulance said a number of those treated “likely would not have survived” had there not been increased medical support on site.

“Or, if they did survive, would not have survived neurologically intact,” she told reporters.

Dr Coombes said a majority of the patients came from Saturday’s Hardcore Til I Die event at Homebush.

A small number remain in hospital – a majority of whom are expected to fully recover, she said.

Police charged dozens of people with drug-related offences across all three Sydney festivals, including a 17-year-old Castle Hill boy who was allegedly found with 579 capsules and $2075 at the Hardcore Till I Die Festival.

In Victoria, revellers at the Rainbow Serpent Festival near Ballarat, will start packing up and winding down on Monday after four days of the event with police planning a targeted drug-driving blitz in the area.

A woman in her 20s and a 24-year-old Ivanhoe man are in a critical condition in hospital after suspected drug overdoses.

In the 24 hours to 7.30am on Monday, Victoria Police caught 13 people with drugs, and issued drug diversions or cannabis cautions.

Three men were arrested for a range of offences including drug trafficking and possessing proceeds of crime during the same period.

The event went ahead amid political debate about pill testing after five people died from suspected drug overdoses at NSW festivals since September.

-with AAP