Overview
Substance use disorder (SUD) is a chronic, relapsing brain condition characterised by compulsive use of alcohol, drugs, or other substances despite serious harmful consequences. It ranges from mild misuse to severe addiction. The substances involved include opioids, stimulants, alcohol, cannabis, and others. SUDs are treatable medical conditions, not moral failures.
How common is it?
Approximately 3 million people in the UK have some form of substance use disorder. About 280,000 adults are in contact with drug treatment services each year. Opioid-related deaths in the UK number over 4,500 per year.
Causes and risk factors
Substances hijack the brain's reward system by flooding it with dopamine. With repeated exposure, the brain adapts, requiring more of the substance to achieve the same effect (tolerance) and producing withdrawal when the substance is not taken.
Common risk factors
- Genetic factors (50% heritable for most SUDs)
- Early initiation of substance use (adolescent brain is particularly vulnerable)
- Mental health conditions (anxiety, depression, PTSD, ADHD) increase risk
- Trauma and adverse childhood experiences
- Social environment: peers, availability, norms
- Chronic pain treated with opioids
- Socioeconomic disadvantage and unemployment
- Previous addiction to any substance
Symptoms
- Strong craving or urge to use the substance
- Loss of control over the amount or duration of use
- Spending large amounts of time obtaining, using, or recovering from the substance
- Failing to meet obligations at work, school, or home
- Continuing use despite relationship, health, or legal problems
- Withdrawal symptoms when not using the substance
- Tolerance: needing more to achieve the same effect
- Giving up important activities because of substance use
When to see a doctor
Seek help from a GP, drug and alcohol service, or helpline. Naloxone (for opioid overdose) should be available to anyone using opioids or those who know them. In an overdose emergency, call 999 immediately.
Diagnosis
AUDIT-C for alcohol, DAST-10 for drugs as brief screening tools. DSM-5 SUD criteria assess severity. Urine drug screen. Blood tests for liver function, hepatitis B/C, HIV.
Treatments
Opioid agonist therapy
Methadone or buprenorphine (Subutex, Suboxone) are the most effective treatments for opioid use disorder. They eliminate withdrawal, reduce cravings, and dramatically reduce overdose death, crime, and HIV transmission. Highly under-utilised.
Naltrexone
Blocks the euphoric effects of opioids and alcohol. Monthly injectable naltrexone (Vivitrol) improves adherence. Effective for alcohol use disorder and as adjunct treatment for opioid use disorder.
Medically assisted withdrawal
Supervised detoxification from alcohol (benzodiazepines), opioids (lofexidine, buprenorphine), or benzodiazepines to prevent dangerous withdrawal complications.
Psychological therapies
Motivational enhancement therapy, CBT, contingency management, and 12-step facilitation. Most effective combined with pharmacotherapy. CBT and contingency management particularly evidence-based.
Naloxone for overdose reversal
Intranasal or IM naloxone rapidly reverses opioid overdose. Should be prescribed to all patients on opioid agonist therapy and available to families. Can be life-saving when administered before ambulance arrival.
Self-care and lifestyle
- Remove substances from the immediate environment where possible
- Identify personal triggers and develop non-substance coping strategies
- Build a social support network of people supportive of recovery
- Peer support groups (AA, NA, SMART Recovery) provide long-term support
Prevention
Prevention focuses on delaying initiation of substance use in adolescents, early identification and treatment of mental health conditions, and reducing social and environmental risk factors. Harm reduction measures (needle exchanges, supervised consumption sites, naloxone distribution) save lives even before full recovery.