The UK has a residential Narconon Drug Rehab building in Hastings, as well as 'ambassadors' around the country in Bristol, Glasgow, Guildford, London, Manchester, Surrey and Sussex as well as those aimed at the muslim community and the arts community. The UK prisons ombudsman has recommended to prison governors that Narconon rehabilitation programs not be used in prisons, however some schools in the UK use Narconon; The Sunday Times said this was because schools are less aware of Narconon's links to the Church of Scientology.

Narconon doesn't tell potential clients or their families that it is a front-group of the cult of Scientology (why does this matter?). Its methods have been described as ineffective and unscientific, and staff are often not medically trained. This is because techniques used in Narconon were created by Scientology founder L. Ron Hubbard, and some of the so-called rehab techniques are the same techniques as the early stages of Scientology. Aspects of the Narconon 'programme' are considered unsafe, such as administration of the extremely high levels of vitamins, especially Niacin and consecutive days of long hours in the Sauna.

In April 2012 in Quebec, Canada, a Narconon Rehab facility was closed down by the authorities. They found it was preying on the vulnerable, that there was no medical supervision or scientific basis to the treatment, that at least four clients were taken to hospital in recent months because of methods used at the centre, and out of 55 criteria, 46 necessary improvements were identified of which 26 were critical. The recording below is an interview with a former client and staff member of the now closed Narconon 'rehab' facility.

The Quebec case is not alone. In Kazakhstan, the director of the local Narconon center was found guilty of the illegal practice of medicine.