A 13-year-old boy is among the dozens of people charged with drug supply following a weekend of music festivals.

He was arrested, along with two 17-year-olds, for supplying MDMA caps at the Goodlife Lost City under 18s festival at Sydney Olympic Park on Saturday.

Another boy was caught in possession of drugs, while two others were hospitalised for drug-related issues.

Police were also out in force at the Ultra Music Festival Parramatta Park on Sunday.

10 people have been charged with supplying drugs, 29 have been issued with infringement notices for drug possession and a further 10 people were taken to hospital by ambulance.

There was also the Secret Garden Music Festival being held at Camden.

Final numbers are yet to be released for the two-day festival but at least 65 people have been caught in possession of drugs.

And, police were disappointed in the behaviour of attendees of the Red Hot Chili Peppers concert at the Hope Estate winery in the Hunter Valley.

44 people were caught with MDMA, cocaine and cannabis.