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Substance Use Disorder or Dependence

What is substance use disorder or dependence?

Substance use disorder (SUD)

Substance use disorder (SUD) is a recognized health condition. It refers to the use of illegal or legal substances in a harmful way. Alcohol is the most commonly used legal drug. SUD causes serious problems at work, school, in relationships, and with the law.

Substances that are often used in this way include:

  • Alcohol.

  • Marijuana.

  • Tobacco.

  • Prescription medicines, such as pain pills, stimulants, or anxiety pills.

  • Methamphetamine.

  • Cocaine.

  • Opiates.

  • Anabolic steroids.

  • Hallucinogens.

  • Inhalants.

Substance dependence

Substance dependence is the use of drugs or alcohol that continues even when serious problems are linked to their use. Signs of dependence include:

  • You need more of the drug to get an effect.

  • You constantly think about getting or using the drug.

  • You have withdrawal symptoms if you reduce or stop using the drug.

  • You spend a lot of time getting, using, and recovering from the effects of the drugs.

  • You withdraw from social and recreational activities.

  • You keep using the drug. You do it even when you know that your ongoing use is causing problems. These include physical, psychological, economic, and family or social problems.

About Xylazine

Xylazine is a sedative and pain reliever approved for animals only. It is not approved or safe for humans. Xylazine has recently been linked to drug overdoses. It has been found in illegal drugs such as heroin and fentanyl. It has also been linked to severe side effects such as:

  • Slow heart rate and breathing.

  • Low blood pressure.

  • Coma.

  • Skin sores.

Care for xylazine overdose or exposure is aimed at helping the body recover.

What causes substance use disorder or dependence?

The cause of SUD and dependence is unclear. It likely includes a mix of genetic, environmental, and emotional factors. The first use of drugs or alcohol is voluntary. But more use quickly changes how the brain feels pleasure. It often changes the structure of the brain. Over time a person no longer has control. There is a compulsive need for the drug.

What are the symptoms of substance use disorder or dependence?

These are the most common behaviors that signal you have a problem with drug or alcohol use:

  • You get high on drugs or get drunk on a regular basis.

  • You lie, especially about how much you are using or drinking.

  • You stay away from friends and family members.

  • You have given up activities you used to enjoy, such as sports or spending time with non-using friends.

  • You talk or think a lot about using drugs or alcohol.

  • You believe you need to use or drink to have fun.

  • You pressure others to use or drink.

  • You get in trouble with the law.

  • You take risks, such as sexual risks or driving under the influence of a substance.

  • Your work suffers due to substance use before, after, or during working or business hours.

  • You miss work due to substance use.

  • You risk your financial security and that of your family to buy drugs or alcohol.

  • You feel depressed, hopeless, or have suicidal feelings.

Many of these symptoms may be caused by other medical problems or mental health conditions. Always see your doctor for a diagnosis.

How is substance use disorder or dependence diagnosed?

A family doctor, psychiatrist, or qualified mental health provider can diagnose substance use disorder. Depending on the substance used, the frequency of use, and the length of time since you last used, your doctor may note:

  • Weight loss.

  • Memory and thinking problems.

  • Constant fatigue.

  • Red eyes.

  • Little concern for hygiene.

  • Unexpected problems in heart rate or blood pressure.

  • Depression, anxiety, agitation, irritability, or sleep problems.

  • Seizures and hallucinations seen in delirium tremens related to alcohol withdrawal.

How is substance use disorder or dependence treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how bad the condition is.

Treatment is serious and complex. People with SUD or dependence can’t simply stop using. Treatment programs have many different components. You can take part in inpatient or outpatient treatment programs. Programs are often based on the type of substance used. They include:

  • Detoxification, if needed.

  • Medicines for withdrawal, to reduce cravings, and to restore normal brain function.

  • Behavioral therapy.

  • Long-term medical follow-up and support.

  • Counseling for both you and any family affected.

  • Support groups.

What are possible complications of substance use disorder or dependence?

Complications of SUD or dependence vary depending on the drug or substance being used. They may include:

  • Liver damage.

  • Heart damage.

  • Memory and thinking problems.

  • Increased risk for infections, such as HIV and other sexually transmitted infections.

  • Pneumonia.

  • Tuberculosis.

  • Injuries to yourself or others.

  • Weight loss.

  • Sleep disturbances.

  • Sexual dysfunction.

  • Depression.

  • Thoughts of suicide.

  • Suicide attempts.

  • Anxiety.

  • Psychosis.

  • Fatal accidental overdoses.

Can substance use disorder or dependence be prevented?

You can do many things to prevent SUD or dependence in your home and community, including:

  • Follow alcohol and drug control laws and policies. This includes obeying the age 21 minimum legal drinking age. And prohibiting the sale of alcohol to intoxicated people.

  • Be a positive role mode. Don't drink. Or if you do, drink responsibly and don't use drugs. Never drive after using substances.

  • Empower young people not to drink or use other drugs.

  • Store prescription medicine and alcohol safely.

  • Correctly dispose of any medicines. Do not share prescription drugs with others.

Key points about substance use disorder or dependence

  • SUD is a recognized health disorder that refers to the use of illegal or legal substances in a harmful way.

  • SUD causes serious problems at work, school, in relationships, and with the law.

  • Substance dependence describes the use of drugs or alcohol that continues even after it has caused serious problems.

  • There are many different treatment programs for SUD. You may need inpatient or outpatient help or a combination of both.

  • SUD is a lifelong condition. It needs ongoing care to manage correctly.

Next steps

Tips to help you get the most from a visit to your doctor:

  • Know the reason for your visit and what you want to happen.

  • Before your visit, write down questions you want answered.

  • Bring someone with you to help you ask questions and remember what your doctor tells you.

  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new directions your doctor gives you.

  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you do not take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your doctor if you have questions, especially after office hours and on weekends.

Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Online Medical Reviewer: Stacey Wojcik MBA BSN RN
Date Last Reviewed: 7/1/2025
© 2000-2025 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.