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What Is Substance Use Disorder (SUD)?

Substance Use Disorder (SUD), also known as drug addiction or drug dependence, is a treatable mental health condition that affects over 20 million people in the USA alone. This condition alters behavior and thinking patterns, causing individuals to lose control over how they take certain substances.

Substance use disorder (SUD) is also considered a chronic brain disorder that affects the way a person’s brain functions, leading to a loss of control over their drug or alcohol use.

SUD involves both physical and psychological dependence on substances, such as alcohol, opioids, stimulants, cannabis, or other drugs. It typically involves a pattern of drug-seeking behavior, intense cravings, and difficulty in controlling or stopping substance use. People with SUD may also experience tolerance, meaning they need higher doses of the substance to achieve the desired effect, and experience withdrawal symptoms when they stop using the substance. People with SUD will continue to use substances despite it causing major social or interpersonal problems, such as failing to complete work or school commitments. SUD, otherwise known as addiction, can take over people’s lives.

It can be difficult to understand why some people turn to the use of substances as the answer is not always clear, even to the person using them. Some reasons include:


A common reason why people abuse substances is to escape life and its hardships. Whether their problems are due to grief, loneliness, or living with other mental health conditions, people may attempt to ease the pain with substances.


Other people take drugs and alcohol to experiment. Young people, in particular, may be curious about the effects of a drug, or simply take it to fit in with their friends. As teens and children are especially vulnerable, peer pressure can lead to SUD.


People may also develop SUD ‘accidentally’. For example, if someone is prescribed medication, either for severe pain or another issue, they can become addicted. In these cases, people may begin seeking alternate ways to obtain the prescription drug or take more than is prescribed.


As some drugs are believed to enhance performance in certain areas of life, people may abuse them. Believing these drugs will boost their success can lead people to SUD, addiction, and dependency.

Substances Associated With SUD

Substance use disorder (SUD) can be associated with various substances.  According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), there are 10 separate classes of drugs recognized in the diagnosis of SUD. These are:

  • Alcohol
  • Caffeine
  • Cannabis
  • Hallucinogens e.g., LSD, psilocybin mushrooms)
  • Inhalants (e.g., solvents, aerosols)
  • Opioids (e.g., heroin, prescription painkillers)
  • Sedatives (e.g., benzodiazepines, barbiturates)
  • Hypnotics (e.g. medications used to induce sleep or treat insomnia when misused or taken in higher doses than prescribed)
  • Stimulants (e.g., cocaine, amphetamines)
  • Tobacco

Signs and Symptoms of SUD

In Yourself

If you start to lose control over your substance-taking habits, you might have SUD. Reach out to a mental health care professional for support if you experience multiple of these symptoms. Common symptoms of SUD include:

  • Feeling strong urges to take the substance regularly
  • Common thoughts about the substance which overpower all other thoughts
  • Higher dosages of the substance needed for the same effect
  • Taking the substance daily
  • Inability to stop taking it once problems arise

For Someone Else

Spotting if someone has a substance use disorder (SUD) can be challenging, as individuals with SUD often hide or deny their behavior. However, there are certain signs and behaviors that may indicate the presence of SUD. When a loved one starts acting out of character and you believe they may have SUD, look out for these symptoms:

  • Appearing anxious, paranoid, or fearful without a reason
  • Showing an unusual lack of motivation like they are tired or “spaced out”
  • Periods of increased energy or instability
  • Sudden mood swings, irritability, or anger
  • Unexplained change in personality or attitude
  • Signs of financial strain or unusual borrowing of money, as individuals with SUD may prioritize obtaining substances over other essential expenses.
  • Physical signs such as bloodshot or glazed eyes, dilated or constricted pupils, changes in appetite or weight, unexplained bruises or marks, tremors, slurred speech, or impaired coordination.
  • A person starts spending time with a new group of friends or becomes isolated from their usual social circle. SUD can lead to changes in social relationships and the formation of new relationships centered around substance use.

Diagnosing SUD (DSM 5 Diagnostic Criteria for Substance Use Disorders)

Substance use disorder (SUD) is diagnosed through a comprehensive evaluation conducted by a qualified healthcare professional or addiction specialist. The diagnostic process typically involves the following steps:

  1. The healthcare professional will conduct an initial assessment by asking questions about the individual’s substance use patterns, substance use and medical history, mental health, and any associated symptoms or difficulties. This information helps form an initial impression of the presence and potential severity of SUD.

    To properly diagnose SUD the healthcare professional will refer to the diagnostic criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association.  It breaks the diagnostic criteria for Substance Use Disorder down into four main categories:

Impaired Control

  • Taking more of the substance, or taking it more frequently, than recommended
  • Wanting to cut down or stop, but being unable to

Social Problems

  • Neglecting relationships, failing to fulfill responsibilities
  • Giving up activities due to substances
  • Inability to complete necessary tasks (at home, school, or work)

Risky Behavior

  • Using in unsafe situations
  • Continuing to use substances despite negative effects

Physical Dependence

  • Building a tolerance to a substance and requiring more of it to have the desired effect
  • Experiencing withdrawal symptoms when a substance is not used
  1. A physical examination may be conducted to assess the individual’s overall health and identify any physical complications associated with substance use. Laboratory tests, such as blood or urine tests, may be conducted to detect the presence of substances in the body and assess their levels.
  2. The healthcare professional may conduct a psychological evaluation to assess for co-occurring mental health disorders or psychological factors that may contribute to or result from SUD.


What Causes SUD?

As SUD is a complex mental health condition, there is no “cause.” However, there are certain conditions that predispose people to SUD, including:

  • Co-current mental health disorders. Some people who struggle with other mental health disorders may attempt to mask their symptoms through drugs and alcohol.
  • Biological factors. Certain biological factors can contribute to the development of SUD. These include genetic predispositions, variations in brain chemistry and structure, and individual differences in metabolism and response to substances. Some individuals may have a heightened vulnerability to developing SUD due to these biological factors.
  • Peer pressure. Particularly for young people, peer pressure remains a common cause of substance use, which may turn into SUD.
  • Early exposure to drugs. Adolescents are particularly vulnerable to developing a SUD due to their state of underdevelopment.
  • Stressful environment. For some, SUD is triggered by a major life change or significant event like losing a loved one.
  • Chronic pain. Some people with chronic pain may self-medicate to manage symptoms.

It’s important to remember that these conditions are not causal of SUD. People can live with multiple of the above conditions and not develop SUD or have none and develop SUD.

Dual Diagnosis and Co-Occurring Disorders

Many people with SUD have a second diagnosis, meaning they have a co-occurring disorder.  Some common co-occurring disorders with SUD include:

  1. Depression. Depression often co-occurs with SUD. Individuals may turn to substances as a way to self-medicate or alleviate symptoms of depression, while substance use can also exacerbate depressive symptoms.
  2. Anxiety Disorders. Conditions such as Generalized Anxiety Disorder, Panic Disorder, Social Anxiety Disorder, or Post-Traumatic Stress Disorder (PTSD) can co-occur with SUD. Substance use may initially provide temporary relief from anxiety symptoms but can ultimately worsen anxiety in the long run.
  3. Bipolar Disorder. Bipolar Disorder, characterized by episodes of mood swings ranging from depression to mania, can co-occur with SUD. Substance use can complicate the management of bipolar symptoms and increase the severity of mood episodes.
  4. Schizophrenia. Individuals with Schizophrenia are more vulnerable to developing SUD. Substance use can worsen symptoms of schizophrenia and interfere with treatment effectiveness.
  5. Personality Disorders. Various Personality Disorders, such as borderline personality disorder or antisocial personality disorder, can co-occur with SUD. These disorders may contribute to impulsive behavior and difficulties in managing substance use.
  6. Eating Disorders. Conditions like Anorexia Nervosa, Bulimia Nervosa, or Binge Eating Disorder can co-occur with SUD. Substance use can be related to attempts to manage weight, cope with emotional distress, or control food cravings.
  7. Attention-Deficit/Hyperactivity Disorder (ADHD). ADHD often co-occurs with SUD, as individuals with ADHD may use substances as a means of self-medication or to cope with difficulties related to attention, impulsivity, or hyperactivity.

To locate a Substance Abuse Counselor near you browse the LifeStance provider directory by selecting “Alcohol and Drug Use Issues” in the “Treatment Areas” drop-down box.

How to Cope With SUD

If you are struggling with your relationship with substances, there is no need to suffer in silence. Seeking professional help might seem overwhelming, but trained SUD professionals at LifeStance are there to support you. Tell your family and friends that you are seeking support for your SUD—it may help you ensure a support network is available when you need it most.

Recovering from an addiction will leave a gap in your free time and thoughts, and it’s best to fill this intentionally. Pick up a new hobby to distract yourself from the temptation to take any substances and enrich your life at the same time. Exercise-related hobbies are a particularly good choice as movement releases endorphins into the bloodstream, uses excess energy, and boosts physical health. Many people find group activities to be especially beneficial due to the accountability and community that comes with them.

When to Seek Emergency Help

In some instances, seeking emergency help is essential. Call 911 in case of:

  • If an individual has taken a potentially toxic or excessive amount of a substance and is displaying symptoms of an overdose, such as unconsciousness, difficulty breathing, severe confusion, seizures, or chest pain, call emergency services (911 in the United States) immediately. Prompt medical attention is crucial in cases of overdose.
  • Suicidal Ideation or Threats. If someone with SUD expresses thoughts of self-harm or suicide, it is essential to take it seriously. Contact emergency services or a local crisis hotline immediately. Stay with the person until help arrives and remove any potential means of self-harm.
  • Severe Withdrawal Symptoms. In some cases, withdrawal from certain substances can be life-threatening. If someone is experiencing severe withdrawal symptoms, such as delirium, hallucinations, seizures, extreme agitation, or high blood pressure, seek immediate medical attention. It is recommended to call emergency services or go to the nearest emergency department.
  • Loss of Consciousness or Unresponsiveness. If an individual with SUD loses consciousness, is unresponsive, or is difficult to awaken, it may indicate a medical emergency. Call for emergency medical assistance right away.
  • Injuries or Accidents. If substance use has led to accidents, injuries, or other medical emergencies, seek immediate medical attention. This includes situations such as falls, severe burns, or injuries sustained while under the influence of substances.
  • Dangerous or Aggressive Behavior. If someone with SUD is displaying dangerous or aggressive behavior, and the situation is escalating or poses a threat to themselves or others, contact emergency services for assistance.