Substance Use Disorder

How addiction affects the brain

Substances trigger large releases of dopamine in the brain's reward circuit, teaching the brain to seek them out. With repeated use:

• the reward system adapts, so ordinary pleasures feel less rewarding and more of the substance is needed (tolerance)
• stress systems become more active when the substance wears off, causing withdrawal and negative feelings
• the prefrontal cortex, which controls decisions and impulses, becomes less effective

This combination makes stopping very hard, even when a person sincerely wants to. Addiction is recognized as a chronic, treatable medical condition, like diabetes or high blood pressure.

DSM-5 criteria

Substance use disorder is diagnosed when at least 2 of these occur within 12 months:

Impaired control

1. using more or for longer than intended
2. wanting or trying to cut down without success
3. spending a lot of time getting, using or recovering
4. cravings

Social impairment

1. failing at major roles at work, school or home
2. continuing despite relationship problems caused by use
3. giving up important activities

Risky use

1. using in physically dangerous situations, such as driving
2. continuing despite physical or psychological problems caused or worsened by use

Pharmacological criteria

1. tolerance
2. withdrawal

Tolerance and withdrawal from medicines taken as prescribed (for example, opioids for pain) do not count by themselves.

Common types

Risk factors

• genetics: family history accounts for a large share of risk
• early use: starting in adolescence, when the brain is developing
• trauma: childhood abuse, neglect and adverse experiences
• mental health conditions: depression, anxiety, ADHD, PTSD, bipolar disorder
• environment: peer use, availability, stress, poverty, social isolation
• method: smoking or injecting leads to faster addiction

Signs to look for

• changes in mood, sleep, appetite or energy
• withdrawing from family, friends and activities
• problems at work or school
• secrecy, lying, money problems or missing valuables
• changes in appearance or hygiene
• smell of alcohol or smoke, drug paraphernalia
• physical signs such as bloodshot eyes, tremors, needle marks or frequent nosebleeds

Health effects

• overdose and death
• infections, including HIV and hepatitis C from shared needles
• liver disease, heart disease, stroke, lung disease, cancers
• injuries and accidents
• depression, anxiety, psychosis and suicidal thoughts
• pregnancy complications and neonatal withdrawal

Treatment

Treatment is individualized and often long-term. Many people need several attempts; relapse is common and is a signal to adjust treatment, not a failure.

Medicines

• Opioid use disorder: buprenorphine, methadone and extended-release naltrexone. These medicines cut the risk of overdose death substantially.
• Alcohol use disorder: naltrexone, acamprosate, disulfiram; others off-label.
• Tobacco: varenicline, nicotine replacement, bupropion.
• Withdrawal management: medically supervised detox for alcohol, benzodiazepines and opioids. See withdrawal syndrome.

No FDA-approved medicines yet exist for stimulant or cannabis use disorders, but behavioral treatments work.

Behavioral therapies

• cognitive behavioral therapy (CBT)
• motivational interviewing
• contingency management: rewards for negative drug tests; highly effective for stimulant use
• family therapy, especially for adolescents

Support and recovery

• peer support groups: Alcoholics Anonymous, Narcotics Anonymous, SMART Recovery
• recovery coaches and sober living
• treatment of co-occurring mental health conditions

Harm reduction

• naloxone to reverse opioid overdoses
• fentanyl test strips
• syringe services
• never using alone

Frequently asked questions

What are the signs of substance use disorder?

Signs include using more than intended, failed attempts to cut down, cravings, spending a lot of time using or recovering, neglecting responsibilities, continuing despite problems, tolerance and withdrawal. Changes in mood, behavior, friends and finances are common.

Is addiction a disease?

Yes. Major medical organizations recognize substance use disorder as a chronic medical condition involving changes in brain function. Like other chronic diseases, it has genetic and environmental causes, can relapse, and responds to treatment.

What is the most effective treatment for addiction?

The most effective approach combines medicines (where available, such as buprenorphine or methadone for opioids, or naltrexone for alcohol) with behavioral therapy and support. Treatment should address co-occurring mental health conditions and be adjusted over time.

Is it dangerous to stop drinking or using drugs suddenly?

It can be. Stopping heavy alcohol or benzodiazepine use suddenly can cause seizures and delirium, which can be fatal. Opioid withdrawal is rarely life-threatening but very uncomfortable and raises overdose risk if use resumes. Get medical advice before stopping.

How can I help a loved one with substance use disorder?

Express concern without blame, learn about treatment options, encourage professional help, and keep naloxone on hand if opioids are involved. Support groups such as Al-Anon and family therapy help families. SAMHSA's helpline (1-800-662-4357) can guide you to services.