Would-be first aiders have been administering ice cube "enemas", in the belief that it will revive people who have overdosed on the party drug GHB.
Drug and medical experts are warning against inserting ice cubes into the rectums of unconscious people, saying it could cause seizures and stroke, and has no benefits.
Paul Dillon, from the NDARC, said: "An overdose in a club is embarrassing enough for the person involved. The sight of the person with their pants around their ankles having people inserting ice cubes is beyond humiliating and potentially dangerous."
