Some people who drink alcohol, use illegal drugs, or misuse prescription or nonprescription medicines may develop substance use disorder. This means that a person uses these substances even though it causes harm to themselves or others.

Substance use disorder can range from mild to severe. The more signs of this disorder you have, the more severe it may be. Moderate to severe substance use disorder is sometimes called addiction. People who have it may find it hard to control their use of these substances.

When a person has substance use disorder:

• They may argue with others about the amount of alcohol or drugs they're using.
• Their job may be affected because of their substance use.
• They may use alcohol or drugs when it's dangerous or illegal, such as when they drive.
• They may have a strong need, or craving, to use alcohol or drugs.
• They may feel like they must use it just to get by.

A person might not realize that their substance use is a problem. They might not use alcohol or drugs in large amounts when they use it. 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 an unconscious attempt at self-treatment for another problem, such as depression.

Using alcohol or drugs can put others at risk. For example, a woman who uses alcohol while pregnant puts her 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 problems, 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 and drugs may be more likely to engage in risky behaviors. For example, they may not use condoms during sex. And they may have more than one sex partner. This increases a person's chance of having an unintended pregnancy and getting sexually transmitted infections (STIs), hepatitis B, and human immunodeficiency virus (HIV). 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

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. Someone may have alcohol use disorder if they find it hard to control their use and they keep using alcohol even though it's having harmful effects on their life.

People who drink alcohol are more likely to have poor grades or job performance. They're more likely to use tobacco products and to experiment with illegal 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 and behavior problems, like high blood pressure; liver, heart, brain, and nervous system problems; and problems with digestion. It may also cause sexual problems, osteoporosis, and cancer.

The use of alcohol with medicines or illegal drugs may increase the effects of each.

Recreational and illegal drugs

People who use marijuana or illegal drugs, such as methamphetamines, cocaine, heroin, or other "street drugs," may develop substance use disorder. They may use drugs to get a "high" or to relieve stress and emotional problems.

Drugs like ecstasy (MDMA), ketamine, GHB, Rohypnol, and LSD may be found at all-night dances, raves, trances, or clubs. These drugs are known as "club drugs." They account for increasing numbers of drug overdoses and emergency room visits. Inhalants like nitrous oxide may also be used at these clubs.

Drugs come in different forms and can be used in different ways. They can be smoked, snorted, inhaled, or taken as pills. They can be put in liquids or food. They can be put in the rectum or vagina or be injected with a needle. Teens and young adults may be at risk for becoming victims of sexual assault or violent behavior in situations where these drugs are used.

Prescription and nonprescription 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 nonprescription medicines, such as cold medicines that have dextromethorphan in them, are being misused by teens and young adults as a way to get a "high."

Household products

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