Frequent use of ketamine may cause memory problems, scientists have said. Ketamine is a drug popular with clubbers.
The University College London boffins came to the conclusion after carrying out a range of memory and psychological tests on 120 people.
From analyses, they found frequent users performed poorly on skills such as recalling names, conversations and patterns, reports The BBC.
Used as an alternative to ecstasy among clubbers, ketamine - or Special K - acts as a stimulant and induces hallucinations.
The study has been published in the Addiction journal.
Lead researcher Dr Celia Morgan said: "Ketamine use is increasing faster than any other drug in the UK, particularly among young people, and has now become a mainstream club drug.
"However, many young people who use this drug may be largely unaware of its damaging properties and its potential for addiction.
"We need to ensure that users are informed of the potentially negative consequences of heavy ketamine use."