What is addiction and how does it affect health?

Short answer
Addiction is a chronic, relapsing condition in which a person compulsively seeks and uses a substance or engages in a behavior despite harmful consequences. It results from changes in brain circuits that control reward, motivation, memory and self-control. Addiction can seriously damage physical health, mental health, relationships, work or school performance, and increase risk of overdose and early death.

What addiction is (key points)
- Substance addiction: compulsive use of alcohol, opioids, stimulants, nicotine, cannabis, benzodiazepines, etc.
- Behavioral (process) addictions: gambling, gaming, internet use, sex, shopping, etc. They don’t involve a drug but can produce similar compulsive patterns and brain changes.
- Core features: tolerance (needing more to get the same effect), withdrawal (unpleasant symptoms when stopping), craving, loss of control, and continued use despite harm.
- Medical model: addiction is best understood as a disorder of the brain’s reward, stress and self-control systems — not a moral failing.

How it affects the brain
- Increased dopamine signaling tied to reward and learning reinforces drug-taking or the behavior.
- Repeated exposure leads to neuroadaptation — reduced sensitivity to natural rewards, stronger cravings, and impaired decision-making (prefrontal cortex dysfunction).
- These brain changes make quitting hard and increase relapse risk even after long periods of abstinence.

How it affects physical health (examples)
- Alcohol: liver disease (fatty liver, hepatitis, cirrhosis), pancreatitis, cardiovascular disease, cancers, accidents.
- Opioids: respiratory depression and fatal overdose, constipation, hormonal problems, increased risk of infections if injected.
- Tobacco/nicotine: COPD, emphysema, lung cancer, heart disease, stroke.
- Stimulants (cocaine, methamphetamine): heart attack, stroke, arrhythmias, dental problems, severe weight loss, mental health symptoms.
- Injecting drugs: higher risk of HIV, hepatitis B and C, bacterial infections, endocarditis.
- Prescription medication misuse: organ damage, overdose, interactions with other drugs.
- Behavioral addictions: sleep disruption, poor nutrition, sedentary lifestyle, increased stress, social and financial harms; may indirectly worsen physical health.

How it affects mental and social health
- Higher rates of depression, anxiety, psychosis, and suicide.
- Impaired cognition (attention, memory, planning).
- Relationship breakups, family stress, job loss, legal problems, financial hardship.
- Stigma and isolation can worsen outcomes and delay help-seeking.

Withdrawal and overdose
- Withdrawal symptoms vary by substance (shaking, sweating, anxiety, nausea, seizures, delirium tremens with severe alcohol withdrawal). Some withdrawals can be life-threatening and require medical supervision.
- Overdose can be fatal (especially with opioids and combinations of central nervous system depressants). Naloxone can reverse opioid overdose if given promptly.

Treatment and harm reduction (effective approaches)
- Addiction is treatable. Approaches include psychosocial therapies (cognitive behavioral therapy, motivational interviewing, contingency management), mutual-support groups (AA, NA), and medication-assisted treatments where available (methadone, buprenorphine, naltrexone for opioid use disorder; nicotine replacement, bupropion, varenicline for tobacco; acamprosate/disulfiram for alcohol in some cases).
- Harm reduction reduces immediate risks: safer use practices, sterile injection equipment, supervised consumption sites, naloxone distribution, and overdose education.
- Integrated care that treats co-occurring mental health conditions and social needs (housing, employment) improves outcomes.

When to seek help
- If use is causing problems (health, relationships, work) or you experience loss of control, tolerance, withdrawal, or strong cravings.
- Seek urgent help for severe withdrawal symptoms, signs of overdose (unresponsiveness, slow/shallow breathing, very small pupils), or thoughts of harming yourself or others.

Practical next steps
- Talk with a primary care doctor, addiction specialist, or mental health professional.
- If immediate danger or suspected overdose, call emergency services right away.
- If you’re in the United States, you can contact SAMHSA’s National Helpline at 1-800-662-HELP (4357) for treatment referral, or call 988 for immediate crisis support. If elsewhere, contact local health services or emergency numbers.

If you want, tell me more about the substance or behavior you’re concerned about and whether you or someone else needs urgent help — I can give more specific information and next steps.