Four people have been hospitalised in New South Wales after suspected ecstasy overdoses, police say.

Three men and a woman, all aged between 20 and 22, were taken to hospital overnight after taking the illicit drug, which was obtained at house parties and a licensed premise in the Cronulla area.

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Police said the group all ingested a hallucinogenic drug in the form of a small blue pill with a scissor logo stamped on it.

Three of the four have since been discharged, while one of the men remains under observation in hospital.

The incident follows the death of 19-year-old Georgina Bartter at the Harbourlife music festival where she reportedly had an allergic reaction after taking one-and-a-half ecstasy tablets.

And on Monday four men in Sydney’s CBD were also treated for a suspected drug overdose.

NSW Ambulance Paramedics treated the men separately when they were called to a George Street nightclub four times between 7pm and 10pm.

Police say the men took the drug gamma-hydroxybutyric acid (known as GHB).

Investigations are underway for both cases.

Meanwhile, More than 200 kilograms of chemicals used to make MDMA has been uncovered at a large drug laboratory on Sydney’s northern beaches.

NSW drug squad police are dismantling the lab discovered at a chemical factory at Warriewood on Friday.

Police were called to the factory following an explosion and fire with officers discovering the mezzanine level had been turned into a lab.

With AAP, ABC