Substance Use Disorder (SUD) refers to the uncontrolled use of substances despite harmful consequences. People with SUD continue to use substances even when they know it is causing or will cause problems in their lives.

What Is Substance Use Disorder?

Substance Use Disorder (SUD) refers to the uncontrolled use of substances despite harmful consequences. People with SUD have an intense focus – sometimes called an addiction – on using a certain substance(s) such as alcohol, tobacco, or other psychoactive substances, to the point of impairing their ability to do activities in their daily lives. People continue to use substances even when they know it is causing or will cause problems in their lives.

Repeated drug use can lead to changes in the way the brain functions. These changes can last long after the immediate intoxication disappears. "Intoxication" is a feeling of intense pleasure and euphoria caused by an addictive substance; with each different substance, there will be different "drunken" symptoms. When using the substance continuously, a person's tolerance will increasingly increase, meaning their need for more of the substance. In addition, stopping substance use can lead to withdrawal symptoms and intense cravings, which often cause anxiety.

People with substance use disorders may have distorted thoughts and behaviors, with common symptoms including intense cravings, personality changes, unusual actions, and so on. This is due to changes in brain areas involved in judgment, decision-making, learning, memory, and behavioral control.

Common Types Of Substances


Immediate impact

Long-term impact

Potential for addiction

Central nervous system calming agents (soothing, analgesic, and anxiety-reducing)

Wine, beer, alcoholic substances

Reduce anxiety, relax

Reduce inhibition

Reduces the ability to think, weakens the body's coordination


Overdose effects:



Breathing may stop and death may occur

The body depends on substances

Severe "withdrawal" syndrome

Destroy the brain

Cirrhosis and other serious diseases

Fetal alcohol syndrome


Opiates, painkillers (including morphine painkillers)

Increase excitement, reduce anxiety

Reduce inhibition

Reduces the ability to think, weakens the body's coordination


Overdose effects:



Breathing may stop and death may occur

Tolerate the dose quickly

Moderate “withdrawal” syndrome


Sedatives, sleeping pills, anxiety relievers

Reduce anxiety

Reduces the ability to think, weakens the body's coordination


Overdose effects:

Breathing may stop, and the heart may stop beating


Especially dangerous when used with alcohol

Severe "withdrawal" syndrome

The body is seriously dependent on substances

Medium to high

Group of central nervous system stimulants (stimulates the nervous system, creates excitement, increases activity, inhibits appetite)


Generate more energy

Increase concentration

Chronic insomnia

Anxiety, depression

Stomach problems


Amphetamine, Methamphetamine, Cocaine

Increase physical and psychological stimulation

Increase activity and violent behavior

Increase pleasure

Reduce inhibitions, loss of judgment

Loss of sleep, loss of appetite

Overdose effects:

Psychotic psychosis

Convulsions, cardiac arrest, death

Physical damage, rapid aging

The body is seriously dependent on substances

Brain damage


Group of hallucinogens (alter consciousness, distort perception, and cause hallucinations)

LSD, Mescaline

Increase sensation intensity

"Distortion" of reality


The feeling of seeing inside



Overdose effects:

Severe confusion, panic

Temporary psychosis (in severe cases)

There is no physical dependence, but psychological dependence may appear


Narcotic group (produces dissociation such as sleepwalking)

Ketamine, MXE

Cause confusion

Reduce pain perception

Distorted feelings

Feelings of separation, dissociation, loss of connection

The body is seriously dependent on substances

Impaired bladder and kidney function

Memory decline

Reduced sociability 


A group of substances with many chemical components, causes many effects


Create energy, relax

The body is seriously dependent on substances

Cardiovascular and digestive problems



Increase pleasure

Relax, reduce anxiety

Increase sensation intensity

Overdose effects (infrequent):

Causes anxiety, panic, paranoia

Reduced motivation to work and social relationships

Impaired short-term and long-term memory

Headache, poor coordination


Inhalants (gasoline, paint, glue...)


Increase pleasure


Overdose effects:

Vomiting, choking when vomiting

Stop breathing, death

The body is seriously dependent on substances

Cause brain damage

Impair hearing function

Cause damage to the kidneys and other internal organs

Depends on each case

Ectasy (Thuốc lắc , MDMA)

Increase energy

Distort feelings

Feel connected and connected to people

Damage the brain, affecting memory and thinking

Nerve destruction

Cause convulsions

Damage to the kidneys and heart



Relax, feel peaceful

Increase sexual desire and pleasure


Overdose effects:

Dizziness, nausea

Loss of coordination

Difficulty breathing, respiratory failure


Lost memory

Loss of consciousness lasts 3 - 4 hours

Dangerous when combined with other sedatives, especially alcohol (can lead to death)

Severe memory problems

Cardiovascular and respiratory diseases


High anxiety


Common types of addictive substances and their effects

Signs And Symptoms

The fundamental characteristic of a substance use disorder is a set of cognitive, behavioral, and physiological symptoms that indicate an individual's continued substance use despite serious associated problems with substances. Diagnostic and Statistical Manual of Mental Disorders: Fifth Edition Text Revision (DSM-5 TR) provides groups of criteria for diagnosing this disorder, including:

Criterion Group 1: Impaired Control Over Substance Use

1. The individual may take the substance in larger amounts or over a longer period than was originally intended. 

2. The individual may express a persistent desire to cut down or regulate substance use and may report multiple unsuccessful efforts to decrease or discontinue use. 

3. The individual may spend a lot of time obtaining the substance, using it, or recovering from its effects. In some instances of more severe substance use disorders, virtually all of the individual’s daily activities revolve around the substance. 

4. The individual exhibits an intense desire or urge for the drug. This can happen at any time but is more likely when in an environment where the drug previously was obtained or used.

Criterion Group 2: Social Impairment 

5. Regular substance use can lead to failure to fulfill major role obligations at work, school, or home. 

6. The individual may continue to use substances despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the substance. 

7. Important social, occupational, or recreational activities may be abandoned or reduced due to substance use.

Criterion Group 3: Risky Use Of The Substance

8. Individuals use substances even in situations in which it is physically hazardous. 

9. The individual may continue to use a substance despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substance. The key issue when evaluating this criterion is not the existence of a problem but the individual's failure to abstain from substance use despite the consequences.

Criterion Group 4: Pharmacological Criteria

10. Signs of Drug Tolerance include requiring a markedly increased dose of the substance to achieve the desired effect or a markedly reduced effect when the usual dose is consumed.

11. Withdrawal syndrome occurs when blood or tissue concentrations of a substance decline in an individual who has maintained prolonged, heavy use of the substance. After developing withdrawal symptoms, individuals tend to consume the substance to relieve these symptoms.

Tolerance and withdrawal symptoms may occur during the appropriate use of prescribed medications given as part of medical treatment (e.g., opioid analgesics, sedatives, stimulants), therefore, it is not counted when diagnosing substance use disorders.

Substance use disorders occur at many different levels. As a general estimate of severity, a mild substance use disorder is suggested by the presence of two to three symptoms, moderate by four to five symptoms, and severe by six or more symptoms. Changing severity across time is also reflected by reductions or increases in the frequency and/or dose of substance use, as assessed by the individual’s report, report of knowledgeable others, clinician’s observations, and biological testing. 

WARNING: The symptoms listed are for reference only. If you suspect that you have substance use disorder, see a psychologist for an accurate diagnosis.

Substance Use Disorder Treatment

Drug Detox

This is the first step in the recovery process. Medically supervised detox helps individuals move through the process safely and stably. During detox, the individual may be given appropriate medications (depending on the substance of abuse) to help minimize withdrawal symptoms and prevent relapse.

Inpatient Rehabilitation

The individual will remain in a treatment facility and receive around-the-clock care and monitoring. Inpatient rehabilitation can take place in different settings, such as a hospital or residential facility.

Outpatient Rehabilitation

Intensive forms of outpatient rehabilitation include partial hospitalization or intensive outpatient programs. These programs require individuals to participate in treatment for several hours each day or once a week, depending on the severity of the disorder.

Psychological Therapy

Behavioral therapies are commonly used to address substance use disorders, including:

  • Cognitive Behavioral Therapy (CBT): helps change thoughts and behavioral patterns that contribute to substance abuse.

  • Motivational Interviewing: helps increase motivation, stop substance abuse, and create positive changes.

  • Contingency management: helps abstain by using positive reinforcement.

  • Identifying alternative and healthier ways to seek pleasure, as a way to replace the need for drugs.

How To Help A Relative Or Friend With A Substance Use Disorder?

Sometimes, realizing that someone you love is facing a substance use problem can cause great difficulty and stress. Here are some helpful tips so you and your loved ones can deal with this situation more effectively:

  • Learning about substance dependence and addiction is an important first step.

  • Show your support by talking to them about your concerns and committing to their treatment. Like other chronic illnesses, the sooner substance use disorder is treated, the better.

  • Show love and care, focus on specific behaviors, and avoid criticism, which may discourage them from sharing.

  • Don't expect them to change without support. Treatment, help, and new coping skills are needed to overcome addiction.

  • Continue to be there for them as an ongoing process of support, and let them know that you are always here and willing to help when needed.

You also need to note some things to avoid as follows:

  • Avoid lectures, threats, bribes, or emotional appeals, as they can embarrass the person and lead to isolation or forced drug use.

  • Don't hide, lie, or justify your behavior; open and honest communication is important so people with substance use disorders get the help they deserve.

  • Avoid confronting people who are intoxicated; you probably won't be able to have a meaningful or reasonable conversation, and this could lead to violence.

  • Try not to feel self-conscious or ashamed about their behavior, or make negative judgments; people with substance use disorders are suffering from an illness, like any other illness, and any specific person or action does not cause the illness.

  • Don't join them; drinking or using alongside someone who has a substance use disorder harms not only them but also yourself.

If you feel you are having symptoms of a substance use disorder, go to a medical facility for a timely examination and diagnosis, or contact the Vietnam-France Psychology Institute via Hotline: 0979.158.463 for specific advice. Early intervention is key to improving health and quality of life.


[1] Tâm bệnh học. Đặng Hoàng Minh

[2] What Is a Substance Use Disorder?.

[3] What is a Substance Use Disorder (SUD)?.

[4] Substance Use Disorder (SUD).



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Phone: 0979.158.463 (Business hours)


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