Problems relating to alcohol or drugs occur across a spectrum of levels of consumption and may be physical, psychological or social in nature. At one extreme, there is a small but significant proportion of people who develop dependence and may require both intensive and extensive support. However, on a population level, huge reductions in the harm caused by psychoactive substances could be made if everyone was encouraged to use a bit less. All health and social care professionals should be able to screen for potential alcohol use disorders, deliver brief advice and refer on to specialist services where appropriate. They should also have an awareness of the common illicit drugs and the potential problems these drugs are associated with. The evidence base for treatment of substance use disorders has developed over the past 30 years, and clinicians should be positive and optimistic that meaningful change in behaviour can be achieved. Prompt referral to the right level of support and treatment may prevent future problems. Recovery support services play a crucial part in sustaining any gains made in treatment, and many people recover without using professionally directed treatment at all. It is estimated that approximately 10 per cent of the population of the USA is in remission from a substance use disorder of any severity.

This chapter starts by describing the key features of drug use disorders and how to assess them, including using objective tests of substance use. The principles of medical treatment are described, incorporating harm reduction strategies, medically assisted withdrawal, agonist therapies and relapse prevention. Opiates are used as a case study to consider the theory and practicalities of each approach, before describing how to integrate psychosocial interventions into an integrated approach to treatment. Stimulants and cannabis are then considered, before a review of the overarching concept of recovery and its application in recovery-orientated systems of care.

This chapter considers the assessment and diagnosis of alcohol use disorders, including the use of screening and a comprehensive assessment process, incorporating an evaluation of substance use and dependence alongside psychological and social wellbeing. A spectrum of treatment approaches are then described, beginning with strategies for managing the intoxicated patient and reducing the harms of alcohol consumption. The importance of preparation and planning for successful medically assisted withdrawal or detoxification is emphasised. Psychosocial interventions form the core of treatment of alcohol use disorders, delivered alongside pharmacotherapies for relapse prevention. Comorbid mental health disorders are considered, before reviewing the importance of patient-reported outcome measures in establishing the outcome of effective treatment for alcohol use disorders.