What is substance (alcohol or drug) use?

Alcohol and drug use: Overview

Some people who drink alcohol, use marijuana or other drugs, or misuse prescription or over-the-counter medicines may develop substance use disorder. This means that a person uses these substances even though it causes harm to themself or others.

A person who has substance use disorder will have two or more of these symptoms:

  • Using more of the substance or using it for a longer time than they ever meant to.
  • Not being able to cut down or control their use.
  • Spending a lot of time getting or using the substance or recovering from the effects.
  • Having a strong need, or craving, for the substance.
  • Not being able to do their main jobs at work, at school, or at home.
  • Continuing to use, even though the substance use hurts their relationships.
  • Not doing important activities because of their substance use.
  • Using substances in situations where doing so is dangerous, such as driving.
  • Using the substance even though they know it's causing health problems.
  • Needing more of the substance to get the same effect or getting less effect from the same amount over time (tolerance).
  • Having uncomfortable symptoms when they stop using the substance or use less (withdrawal).

Substance use disorder can range from mild to severe. The more symptoms of this disorder you have, the more severe it may be.

A person might not realize that their substance use is a problem. They might not use alcohol or drugs in large amounts at one time. Or they might go for days or weeks between drinking episodes or using drugs. But even if they don't drink or use drugs very often, their substance use could still be harmful and put them at risk.

Alcohol and drug use may be a person's way of trying to self-treat another condition, such as depression.

Using alcohol or drugs can put others at risk. For example:

  • Using alcohol while pregnant puts the baby at risk for problems from fetal alcohol syndrome. Alcohol may affect the baby's growth and development, behavior, and ability to learn.
  • Children who are exposed to alcohol or drug use in the home may develop mental health conditions, such as depression and anxiety. They may have behavioral problems and trouble with learning and do poorly in school. And they may be more likely to develop substance use disorder.
  • Alcohol and drugs can affect a teen's brain development. They can also affect emotional and social development. Alcohol use can cause changes in a teen's alertness, perception, movement, judgment, and attention. This can make it harder for teens to think, learn, reason, and make good choices.

People who use alcohol or drugs may be more likely to engage in risky behaviors. For example, they may not use condoms during sex. Or they may have more than one sex partner. This increases the risk of unintended pregnancy and sexually transmitted infections (STIs). They may drive when "high" or when they've had too much to drink. This may increase the risk of injury or car crashes.


Alcohol is part of many people's lives. It may have a place in cultural and family traditions. So it may be hard to know when someone is drinking too much and when it's a sign of alcohol use disorder.

People who drink too much alcohol are more likely to have poor grades or job performance. They're more likely to use tobacco products and to experiment with marijuana or other drugs. And their drinking may increase their risk of getting hurt or being in a car crash.

Over time, drinking too much alcohol may cause health problems, like high blood pressure, problems with digestion, and liver, heart, brain, and nervous system problems. It may also cause sexual problems, osteoporosis, and cancer.

The use of alcohol with medicines, marijuana, or other drugs may increase the effects of each. Using alcohol along with opioids increases the risk of opioid overdose.

Recreational drugs

People who use drugs such as marijuana, cocaine, heroin, or meth, may develop substance use disorder. People use many drugs for recreational purposes, including some that are also used as medicines. Examples include opioids, ketamine, and LSD. People may use drugs to get a "high" or to relieve stress and emotional problems.

Drugs come in different forms and can be used in different ways. They may be smoked, snorted, inhaled, or taken as pills. They may be put in liquids or food. They may be put in the rectum or vagina or be injected with a needle.

Teens and young adults may be at higher risk of being victims of sexual assault or violent behavior in situations where drugs are used.

Prescription and over-the-counter medicines

Some people misuse prescription medicines, like opioids (such as OxyContin and Norco), benzodiazepines (such as Valium and Xanax), and stimulants (such as Ritalin and Adderall). Misusing prescription medicines can cause serious harm and, in some cases, even death.

Some over-the-counter medicines, such as cold medicines that have dextromethorphan in them, are being misused by teens and young adults as a way to get "high."


Glue, shoe polish, cleaning fluids, and aerosols are common products with ingredients that can also be used to get a "high."

What are signs of substance use?

Signs that a person is using substances such as drugs or alcohol include behavior changes and physical changes. Substance use is more likely to cause changes in behavior than physical signs.

Behavior changes

These may include:

  • Changes in sleeping or eating habits, such as trouble sleeping or eating more or less than usual.
  • Paying less attention to dressing and grooming.
  • Up-and-down moods, a mood or attitude that is getting worse, or not caring about the future.
  • Sneaky behavior, lying, or stealing.
  • Poor family relationships, or relationships that are getting worse.
  • New problems at work or school, or problems with the law.
  • Not keeping up with old friends and activities. The person may find new friends and not want old friends to meet them.

These signs don't always mean that a person is using substances. They could be a sign of depression, stress, or another medical condition.

Physical changes

These may include:

  • Red eyes, a sore throat, a dry cough, and feeling tired.
  • Needle marks on the arm or other area of the body.
  • Small "pinpoint" pupils in the eyes.
  • Losing weight without trying.

What can you do if you're worried about your own or another person's alcohol or drug use?

If you are concerned about your own or another person's alcohol or drug use, learn what steps to take to help yourself or someone else.

  • Do not ignore the problem.
  • Know the signs of substance use. These include being unable to cut down or control use, continuing to use even though it hurts a person's relationships, and having problems at work, school, or home.
  • Make an appointment with a doctor or another health professional, such as a counselor, to discuss steps for getting treatment.
  • Find out when support groups, such as Alcoholics Anonymous (AA) or Narcotics Anonymous (NA), meet. These self-help groups help members get sober and stay that way. There are also support groups for family members and friends.
  • Ask the other person if they would accept help. Don't give up after the first "no." Keep asking. If the person agrees, arrange for help that same day.
  • Provide support for the other person during detox or other treatment.
  • Help set up community services in the home, if needed. Older adults may benefit from services like home care, nutritional programs, transportation programs, and other services.
  • Help with decision-making. Some people who misuse substances can't process information or communicate their decisions well.
  • Check out what services are available in your area.
    • If you work, talk to your human resources department about getting a referral to your employee assistance program, if your employer offers it.
    • Contact the national Substance Abuse and Mental Health Services Administration (SAMHSA) to learn about treatment programs in your area. Call the SAMHSA help line at 1-800-662-HELP (4357) or go online to www.samhsa.gov/find-help. Talking to someone about your feelings about substance use can help.

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The content above contains general health information provided by Healthwise, Incorporated, and reviewed by its medical experts. This content should not replace the advice of your healthcare provider. Not all treatments or services described are offered as services by us. For recommended treatments, please consult your healthcare provider.