Substance use and addiction

A substance use disorder is a health condition in which a person keeps using alcohol or a drug even though it is causing harm. It changes how the brain handles craving, stress and choices. It is not a weakness or a lack of willpower.^1,2

This condition affects people of every age, job and background, including older adults. It is common, and it is treatable. This page gives the big picture and links to each topic in this section.

What is a substance use disorder?

A substance use disorder means that using a substance has taken hold of a person's life. The person may use more than planned, find it hard to cut down, and keep using despite problems at home, at work or with health.¹

Two body changes are common. Tolerance means needing more of a substance to get the same effect. Withdrawal means feeling sick or shaky when the substance wears off.¹

Doctors rate the disorder as mild, moderate or severe. For alcohol, they count how many signs of the disorder a person has. Two to three signs is mild, four to five is moderate, and six or more is severe.³ You can read the signs in detail on signs of a substance use problem.

Why it is a treatable health condition

Addiction is a chronic condition, which means it can come and go over time. Experts compare it to heart disease. Both can often be prevented and treated, and both can be serious if left alone.²

Stress can bring on a return to use, and brain changes can last a long time after someone stops.² That is why treatment is not a one-time fix. Many people need support over months or years. A return to use is common and does not mean treatment has failed. It is a sign that the plan needs a change. Read more on treatment and recovery.

Person-first words matter too. Saying "a person with a substance use disorder" instead of "an addict" or "an alcoholic" reduces shame. Shame keeps many people from asking for help.

How common is it?

Alcohol is the most common problem. In 2024, about 27.9 million people age 12 and older (9.7%) had an alcohol use disorder in the past year. Among adults, it was about 27.1 million, or 10.3%.⁴

Overdose deaths are a major concern. The U.S. had 79,384 drug overdose deaths in 2024. That is down from about 105,000 in 2023, but it is still a great many lives.^7,9 About 68 in 100 of the 2024 deaths involved an opioid. Most of those involved a strong, man-made opioid such as fentanyl.⁹

Alcohol

Alcohol is legal and common, so its harm is easy to miss. In the U.S., one standard drink is about 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of spirits.¹⁰ The CDC defines moderate drinking as no more than 2 drinks a day for men and 1 a day for women. Bingeing means 4 or more drinks on one occasion for women, or 5 or more for men.¹¹ Drinking can raise the risk of several cancers, liver disease, high blood pressure, falls and depression.¹¹

Three medicines are FDA-approved for alcohol use disorder. They are not habit-forming.³ Read more on alcohol use disorder.

Opioids and overdose

Opioids include prescription pain medicines, heroin and fentanyl. Illegally made fentanyl is a major danger. Opioids slow breathing, and too much can stop it.^9,7

Signs of overdose include being very sleepy, not waking up when spoken to loudly, slow or stopped breathing, and small pupils.⁷ Call 911 right away.

Naloxone is a safe medicine that can reverse an opioid overdose. It comes as a nasal spray or an injection, and anyone can use it with no medical training. It can restore breathing in 2 to 3 minutes. More than one dose may be needed, especially with fentanyl. It does no harm if the overdose was not from opioids.⁷ The FDA approved the first nonprescription naloxone nasal spray in March 2023, and the CDC says it is now sold over the counter in all 50 states.^7,12

After giving naloxone, call 911 and stay with the person until help arrives, or for at least four hours.⁷ You cannot give it to yourself, so tell someone you live with where it is kept. Most states also have Good Samaritan laws that protect people who call for help.⁷ Using alone raises the risk, because no one is there to call for help.

Three medicines can treat opioid use disorder: methadone, buprenorphine and naltrexone. They help with cravings and withdrawal, and they lower the chance of an opioid overdose.¹³ Strong evidence Read more on opioids and overdose.

Cannabis, sedatives and stimulants

Cannabis (marijuana). About 3 in 10 people who use cannabis have a cannabis use disorder. Strong, concentrated THC products are linked to more severe symptoms. Cannabis is also linked to mental health problems such as psychosis, though scientists do not yet fully understand how.¹⁴ It slows reaction time, so it is unsafe before driving.¹⁴

Sedatives and sleeping pills. Benzodiazepines (such as lorazepam and diazepam) are used for anxiety and sleep. The FDA requires a boxed warning, its strongest kind, about misuse, addiction, physical dependence and withdrawal. Stopping suddenly can cause seizures. Do not stop on your own. Ask your doctor about a slow, planned taper. Mixing these medicines with opioids or alcohol can cause deadly breathing problems.⁶

Stimulants. Methamphetamine is a very addictive stimulant that can quickly lead to dependence. It can also raise body temperature to a dangerous level.¹⁵ Stimulants include cocaine and misused ADHD medicines as well. Read more on cannabis, sedatives and stimulants.

Substance use and other mental health conditions

Many people with a substance use disorder also live with depression, anxiety or bipolar disorder. Shared causes include stress, trauma and genes. Each problem can make the other worse.¹ Treatment works best when both are treated together.¹

See our pages on depression, anxiety and PTSD and trauma. If you are having thoughts of suicide, call or text 988. Use our safety plan tool to prepare for hard moments.

Substance use in later life

Older bodies handle alcohol differently. Less body water and muscle mean the same drink leads to a higher blood alcohol level. Balance, attention and driving are affected more.¹⁶ Many older adults take medicines that mix badly with alcohol, such as sleep or anxiety pills, opioid pain medicines, aspirin and acetaminophen. The mix raises the risk of falls, bleeding, liver damage and slowed breathing.^16,17

Substance use in older adults is often missed, because signs like confusion, falls or poor sleep are blamed on aging. Read alcohol, medicines and older adults and alcohol in later life. Check your medicines with our medicines and mood guide.

Getting treatment

Treatment can include medicines, talk therapy, support groups, or a mix. NIMH lists several therapies, including cognitive behavioral therapy (CBT), motivational interviewing and contingency management (small rewards for healthy steps).¹ Start with your primary care doctor, who can refer you to a specialist.¹ You can also call the SAMHSA National Helpline at 1-800-662-4357. It is free, private and open every day, all day, in English and Spanish.⁸

Supporting someone you love

You cannot force a person to change, but you can help. Staying calm, avoiding blame, and learning about treatment all matter. Look after your own health too. Read helping a family member, how to start a conversation and caregiver burnout. More support is on our help page.

All substance use topics

• Signs of a substance use problem
• Alcohol use disorder
• Opioids and overdose
• Cannabis, sedatives and stimulants
• Treatment and recovery
• Helping a family member
• Alcohol, medicines and older adults

In this section

When to get help

See a doctor if you or someone you love is using more than planned, cannot cut down, or is having problems because of it. You do not have to wait until things are very bad.

Education only. This page is general information written from the sources listed. It is not medical, legal or financial advice and does not replace a doctor, therapist or lawyer who knows your situation. How we write and check pages.