TEN people have been charged with drug supply at a music festival in western Sydney and another 10 were taken to hospital for overdoses during a weekend of festival chaos at Ultra, Secret Garden and Good Life in the NSW capital.

Police searched 395 people at the Ultra Music Festival, which drew a 20,000 to Parramatta Park yesterday.

Twenty-nine revellers were issued with infringement notices, 28 for possession of MDMA and one for cocaine.

More than 40 charges were laid, including 10 for supplying a prohibited drug. A further 35 people were refused entry to the festival and 66 were removed.

Twenty-nine revellers were issued criminal infringement notices, 28 for possession of MDMA, and one for cocaine, along with 13 cannabis cautions.

One of the festival's revellers was caught on camera inside the event when he mistook a 9 News cameraman for a drug dealer.

"Are you selling caps at all?" the festival-goer asks the cameraman.

"Nah, no, no, no," the cameraman quickly replies.

It comes after three teenagers, including a 13-year-old, were charged with supplying drugs at a different under-18s dance festival at Sydney Olympic Park on Saturday.

Three males, two 17-year-olds and a 13-year-old, were allegedly caught carrying MDMA caps at Goodlife Lost City 2019 at Sydney Showground. They were arrested and charged with supplying drugs.

Police were told two teenagers were taken to hospital with suspected drug-related health issues.

Both have since been released.

A 16-year-old male was issued a court attendance notice for drug possession.

Police seized more drugs on Saturday at the two-day Secret Garden festival in Camden and at the Red Hot Chili Peppers concert in the Hunter Valley.

One officer had snot blown on him at the Hope Estate winery venue as he attempted to eject a 25-year-old man for intoxication at 9pm.

The arrests and hospitalisations come after a spate of overdoses at music festivals over summer, including the deaths of five people in NSW alone between September and January.