All five people rushed to hospital following a suspected drug overdose on a boat off South Stradbroke Island in south-east Queensland have been discharged from hospital.

Four men and one woman were rushed to hospital on Sunday afternoon, with one man unconscious and in a critical condition.

Initially, revellers made a frantic call to emergency services just after 5:00pm reporting six people had lost consciousness at the Dirty Funken Beats island party.

Paramedics said the sixth person left the scene before they arrived.

They were told the group in their 20s took the drug fantasy, with Patrick Berry from the Queensland Ambulance Service later confirming they appeared to have consumed illicit drugs.

Mr Berry said a private boat was used to rush the group to hospital on the nearby Gold Coast.

"With any unknown recreational drug we don't know how much they have taken and what the long term effects are going to be for those individuals," he said.

This morning, a Robina Hospital spokesman said all five people were discharged.

Last night, one man was taken to Robina Hospital with the remainder going to Gold Coast University Hospital.

Superintendent Ben Hanbidge from the Gold Coast said police were investigating but were yet to charge anyone.

"Certainly we're very keen to hear from anyone who might have been at that rave party that might have some information about this alleged drug taking," he said.

"We'd be keen to hear from them because these people really were one step away from dying and I don't think they realise just how dangerous it is to take these sorts of drugs in these environments."

Superintendent Ben Hambidge said he would look at the approval process in place for such events.

"We have to look at what the approval process is and the risk management strategies," he said.

"The fact they are isolated makes it a more difficult proposal to police and deal with and respond to in case of an emergency."

The ABC understands the company responsible for the Stradbroke Island event also hosted a cruise on Sydney Harbour at Easter.

It was reportedly shut down by police amid allegations of drug overdoses by partygoers.