Premier Daniel Andrews says he will not reconsider his opposition to recreational drug testing despite a mass overdose on Friday night at a Festival Hall rave.

However, drug law reform advocates say legalising drug testing could potentially save lives.

Nine people were taken to hospital, some of them in a critical condition, after being treated for suspected drug overdoses at the I Am Hardstyle event at the West Melbourne venue. Several others affected made their own way to hospital.

An 18-year-old man was still fighting for life and another three, including a 17-year-old man, remained in hospital on Sunday night.

Ambulance Victoria state health commander Paul Holman said on Saturday the overdoses could have proved lethal if partygoers hadn't received medical help as quickly as they did.