Auckland Police are worried about a spate of incidents involving the date-rape drug GHB.

They say seven people have needed hospital treatment in just 48 hours.

GHB is a class B substance, it has side effects including sweating, loss of consciousness, vomiting and hallucinations.

Detectives are now looking into cases, in which women have been taken to hospital having consumed an unconfirmed illegal substance.

Detective Senior Sergeant Marcia Murray said the consequences of taking illegal substances can be life threatening, and police want people to recognise the risk they are taking.

"If you are taking substances where you don't know where it is from or what it contains, you are taking a very serious risk with your health."

She said people should seek medical attention if they have taken a drug because of how quickly things can take a turn for the worse.