Drug Dependency Units are usually led by a consultant psychiatrist specialising in drug or substance misuse and will be staffed by one or more of the following professions – social workers, psychiatric and general nurses, counsellors and clinical psychologists.

DDUs were established within the NHS in the 1960s in order to respond to the growing number of opiate users, and are predominately run by the NHS. They continue to provide services mainly to opiate users and traditionally they were the service that prescribed methadone. In establishing DDUs, the Government intended to draw prescribing away from GPs into specialist units. However, as drug prevalence increased over the next 30 years this became less realistic and in the light of recent moves towards community care, less desirable.

Increasingly DDUs will be one of a range of prescribers in any areas, with community agencies and now GPs also actively involved. In many areas DDUs are becoming specialised, seeking to use their skills to work with the most problematic drug users or those requiring the specialist skills of the multi–disciplinary team e.g. drug users with mental health problems, poly-drug users, pregnant women etc, those that cannot be managed by the GP. In these cases the DDUs are likely to leave the bulk of prescribing to community agencies and GPs. However, in some areas, particularly those with relatively low drug prevalence, DDUs may be the main or only prescriber. Some areas may not have a DDU but may have a consultant psychiatrist with some responsibility for drug misuse.

Most services will have a full time nurse, who can offer HIV & Hepatitis testing, Hepatitis B vaccinations, wound dressing and onward referral as necessary, for example to the tissue viability nurse. They can have very long waiting lists depending on the area, up to one year.