Substance Use Disorder and Mental Illness

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Substance Use Disorder and Mental Illness

Substance Use Disorder and Mental Illness

Substance use disorder is a condition in which a person is dependent on a substance, such as drugs or alcohol. A mental illness is a condition that occurs when someone experiences changes in mood, behavior, or thinking. Sometimes, these two conditions can occur at the same time (co-occurring disorders) and may be diagnosed together (dual diagnosis).

What is the relationship between substance use disorder and mental illness?

Substance use disorder and mental illness can share symptoms and can have similar causes, such as exposure to stress or changes in brain chemicals. The risk for developing both of these conditions can be passed from parent to child (inherited). People with mental illnesses sometimes use drugs to try to relieve symptoms, and this can lead to substance use disorder. Substance use disorders occur more often in people who have depression, schizophrenia, anxiety, or personality disorders.

Also, when some drugs are used regularly, they can cause people to have symptoms of mental illness.

What are the signs or symptoms?

Symptoms vary widely for substance use disorder and mental illness, especially because these conditions can be present at the same time.

Signs of a substance use disorder

  • Failure to meet responsibilities at home, work, or school.
  • Using substances in risky situations, such as while driving or using machinery.
  • Taking serious risks to get drugs or alcohol.
  • Spending less time on activities or hobbies that used to be important.
  • Changes in personality or attitude for no reason, such as angry outbursts, symptoms of anxiety, or unusual giddiness.
  • Trying to hide the amount of drugs or alcohol used.
  • Increased substance use over time, or needing to use more of a substance to feel the same effects (developing a tolerance).
  • Physical symptoms may include:
    • Sudden weight loss or gain.
    • Sleeping too much or too little.
    • Uncontrolled trembling or shaking (tremors), slurred speech, or lack of coordination.
  • Continuing to use alcohol or a drug even though using it has led to bad outcomes or consequences, such as losing a job or ending a relationship.

Signs and symptoms of mental illness

  • Withdrawing from friends and family, or sudden changes in social behaviors or hobbies.
  • Aggression toward people and animals.
  • Repeatedly breaking serious rules or breaking the law.
  • Persistent feelings of sadness, hopelessness, or thoughts of suicide.
  • Having persistent thoughts or urges that are unpleasant or feel out of control (involuntary). The person may feel the need to act on the urges in order to reduce anxiety.
  • False beliefs (delusions).
  • Seeing, hearing, tasting, smelling, or feeling things that are not real (hallucinations).
  • Other signs include:
    • Sleeping too much or too little.
    • Weight loss or weight gain.
    • Being easily distracted.
    • Extreme mood changes (mood swings).
    • Confused thinking or trouble concentrating.

How is this diagnosed?

Substance use disorder and mental illnesses can be difficult to diagnose at the same time because of how varied and complex the symptoms are. Because these conditions can interact, one condition may be missed. This is why it is important to be completely honest with your health care provider about substance use and your other symptoms.

Diagnosing your condition may include:
  • A physical exam.
  • A review of your medical history and your symptoms.

Your health care provider may refer you to a mental health professional for a psychiatric evaluation. This may include assessments of:
  • Your use of substances.
  • Your risk of suicide.
  • Your risk of aggressive behaviors.
  • Your lifestyle, environment, and social situations.
  • Your medical health.
  • Your mental health and behavioral history.

How is this treated?

Three people participating in a support group.

It is best to treat substance use disorder and mental illness at the same time (integrated treatment approach). Treatment usually involves more than one of the following methods:
  • Detox. This refers to stopping substance abuse while being monitored by trained medical staff. This is usually the first step in treatment. Detox can last for up to 7 days.
  • Rehabilitation. This involves staying in a treatment center where you can have medical and mental health support all the time.
  • Medicines to relieve symptoms of mental illness and to control symptoms that are caused by stopping substance abuse (withdrawal symptoms).
  • Support groups. These groups encourage you to talk about your fears, frustrations, and anxieties with others who have the same condition.
  • Talk therapy. This is one-on-one therapy that can help you learn about your illness and learn ways to cope with symptoms or side effects.

Follow these instructions at home:


  • Take over-the-counter and prescription medicines only as told by your health care provider.
  • Do not stop taking medicines unless you ask your health care provider if it is safe to do that.
  • Tell your health care provider about any medicine side effects that you experience.


  • Exercise regularly. Aim for 150 minutes of moderate exercise (such as walking or biking) or 75 minutes of vigorous exercise (such as running) each week.
  • Eat a healthy diet with plenty of fruits and vegetables, whole grains, and lean proteins.
  • Avoid caffeine and tobacco. These can worsen symptoms and anxiety.
  • Do not drink alcohol or use drugs.
  • Try to get 7–9 hours of sleep each night. To do this:
    • Keep your bedroom cool and dark.
    • Do not eat a heavy meal during the hour before you go to bed.
    • Do not have caffeine before bedtime.
    • Avoid screen time during the few hours before bedtime. This means not watching TV and not using a computer, mobile phone, or tablet.

General instructions

  • Follow your treatment plan as directed. Work with your health care provider to adjust your treatment plan as needed.
  • Attend support group or therapy sessions as directed.
  • Explain your diagnosis to your friends and family. Let them know what your symptoms are and what things cause your symptoms to start (triggers).
  • Avoid triggers or stressors that may worsen your symptoms or cause you to use alcohol or drugs. Spend time with family and friends who do not use substances.
  • Make time to relax and do self-soothing activities, such as meditating or listening to music.
  • Keep all follow-up visits. This is important.

Where to find support

You may find support for coping with substance use disorder and mental illness from:
  • Your health care providers or your therapist. These providers can treat you or can help you find services to treat your condition.
  • Local support groups for people with your condition. Your health care provider or therapist may be able to recommend a support group. This may be a hospital support group, a National Alliance on Mental Illness (NAMI) support group, or a 12-step group such as Alcoholics Anonymous (AA) or Narcotics Anonymous (NA).
  • Family and friends. Let them know what they can do to best support you through your recovery process.

Where to find more information

  • Substance Abuse and Mental Health Services Administration (SAMHSA):
    • National Helpline, to talk with a person who can help you find information about treatment services in your area: 1‑877‑726‑4727 (1‑877‑SAMHSA7)
  • U.S. Department of Health and Human Services mental health services:
  • National Alliance on Mental Illness (NAMI):

Contact a health care provider if:

  • Your symptoms get worse or they do not get better.
  • You have negative side effects from taking medicines.
  • You want to discuss stopping medicines or treatment.
  • You start using a substance again (have a relapse).

Get help right away if:

  • You have thoughts about harming yourself or others.

If you ever feel like you may hurt yourself or others, or have thoughts about taking your own life, get help right away. Go to your nearest emergency department or:
  • Call your local emergency services (911 in the U.S.).
  • Call a suicide crisis helpline, such as the National Suicide Prevention Lifeline at 1-800-273-8255 or 988 in the U.S. This is open 24 hours a day in the U.S.
  • Text the Crisis Text Line at 741741 (in the U.S.).


  • Substance use disorder and mental illness can occur at the same time (co-occurring disorders), and they may be diagnosed together (dual diagnosis).
  • These conditions can be difficult to diagnose at the same time. It is important to be completely honest with your health care provider about your substance use and your other symptoms.
  • It is best to treat substance use disorder and mental illness at the same time (integrated treatment approach).
  • Identifying new ways to deal with triggers and difficult situations is an important part of recovery.
  • Keep all follow-up visits. Attend support groups or treatment programs as directed.

This information is not intended to replace advice given to you by your health care provider. Make sure you discuss any questions you have with your health care provider.