The arrests came after a blitz on crowd safety at the five-day festival in Pyalong in central Victoria.

Inspector Libby Murphy said the presence of drugs at festivals was "really concerning".

"I'm amazed that people are willingly gambling with their lives by taking these dangerous substances," Inspector Murphy said.

"At the end of the day, as a user, you really have no idea what you are putting in your body, and you have no idea what it will do to you."

Police also cautioned 12 people on possession of cannabis and issued two drug diversion notices.

They confirmed other Earthcore attendees had been taken to hospital after drug use.

The Earthcore festival also saw a small tornado - or willy-willy - which festival goers have dubbed the 'Doofnado'.

The arrests follow the death of a 25-year-old woman at Sydney's Stereosonic music festival on Saturday.

The woman suffered a cardiac arrest believed to be caused by a drug overdose. Seventy other attendees were charged with drug offences.

Victoria Police is currently finalising its preparations for this weekend's Stereosonic music festival and details will be released later this week.