Parliament has voted in favour of reclassifying the drug ketamine - known as Special K - and imposing tougher controls on its importation and storage.
The drug, which is mainly used by vets as an anaesthetic, is taken by recreational drug users for its hallucinogenic effects.
The Expert Advisory Committee on Drugs says ketamine poses a moderate risk of harm and should be listed as a class C4 drug.
The reclassification means hospitals and veterinarians will have to keep the drug under lock and key and stiffer penalties for its illegal importation or supply.
There was cross-party support for the move when it was put to Parliament on Tuesday afternoon but a date has still to be set for the change to be made.