Researchers believe there could be 46,000 crack cocaine users aged 15-44 in London, suggesting one in every hundred young adult Londoners could be a user.
Research published online in the Society for the Study of Addiction, shows how researchers from Imperial College London and the University of Bristol, used statistical modelling to estimate the number of crack cocaine users aged between 15 and 44 across London.
Dr Matthew Hickman, from Imperial College London, and an author of the paper, said: "Although crack cocaine use has been a cause for concern in many countries since the 1980s, there has not been the predicted epidemic across the UK until now. We must be cautious but the analysis suggests there is a substantial problem.
"With almost 60 percent of crack-cocaine users also opiate users, part of the increase in use is driven by heroin users, which has implications for treatment and prevention"
The researchers looked at data for 12 London boroughs from a number of sources reporting crack cocaine use, including numbers in specialist drug treatment, arrested, accident and emergency and community surveys, and the numbers of injecting drug users.