Medically Reviewed

Drug & Alcohol Addiction: Guide to Understanding Addiction

4 min read · 7 sections

Addiction is a complex condition that is often misunderstood.1 Demystifying this mental health issue can help people that struggle with addiction and their loved ones better understand the disease in order to address the problem.

This page will define some key terms, analyze the scope of substance use disorders in the United States, present the criteria used when diagnosing addiction, and go over available treatment options.

Definitions Related to Addiction and Substance Use

doctor explaining addiction to a patient

Addiction is a chronic, relapsing disorder that involves compulsive substance seeking and use despite negative and harmful consequences.2 The clinical term for this condition is called “substance use disorder” (SUD).3

It is helpful to understand terms related to substance use disorders such as:

  • Substance misuse (preferred term vs. substance abuse). Substance abuse has historically been described as using illicit drugs or using legal drugs or alcohol in unintended ways or in excessive quantities. This may include taking more than prescribed, taking someone else’s medication, or ingesting substances in unintended ways (e.g., intravenous drug use as opposed to oral use).4 There is a strong association between the term “abuse” and judgment or punishment, which is why many experts prefer to use the terms ”substance use” or “substance misuse.” The stigma surrounding addiction and mental health issues may make others afraid, angry, or distant toward people in need, and may deter people with substance use disorder from seeking professional help. Simple changes in language can help eliminate some of these barriers.5
  • Dependence is when someone’s body adapts to a substance, becoming so used to the substance being present in the system that when the individual cuts back on their use or quits, withdrawal symptoms emerge.6 Dependence often indicates addiction; however, in some cases, someone may be dependent on a medicinal drug without being addicted.3
  • Withdrawal refers to the psychological and physical symptoms that occur as a result of physiological dependence to a substance. Someone whose body has adapted so that it is dependent on a substance will experience withdrawal symptoms after reducing or ceasing their use of a substance.6
  • Person with a substance use disorder, formerly “addict.” People sometimes use the word “addict” to refer to someone with substance use disorder. “Addict” is another term that has fallen out of favor with professionals in the field of addiction treatment. Person-first language—for example, “a person with a substance use disorder,” or “person struggling with addiction”—more accurately implies the person in question has a problem, not that they are the problem.5
  • When someone with a substance use disorder abstains from using drugs or alcohol they are in recovery. Substance use disorder is a chronic, relapsing medical condition and, as such, there is no known cure. The rate of relapse for addiction is comparable to other chronic diseases like diabetes and cancer; however, just like those diseases, addiction can be successfully managed. Many people with SUDs are able to quit drugs and alcohol for good, leading fulfilling lives in recovery.7

Addiction Statistics

Millions of Americans struggle with a substance use disorder. In fact, addiction statistics compiled in 2020 show that among people 12 years old or older in the United States:8

  • 3 million (14.5%) struggled with a substance use disorder in the past year.
  • Alcohol use disorder (AUD) was the most common addiction, with around 28.3 million (10.2%) people struggling with it in the past year.
  • Roughly 18.4 million (4.3%) had an illicit drug use disorder in the past year.
  • Around 6.5 million (2.3%) had both an illicit drug use disorder and an alcohol use disorder in the past year.

Symptoms of Addiction

The following symptoms are used by medical professionals to determine the presence of a SUD:9

  1. Experiencing cravings to use substances
  2. Using substances in physically hazardous situations, such as while driving or playing sports.
  3. Missing or neglecting work, school, and family obligations due to substance use
  4. Continuing to use substances despite experiencing problems in your relationships with others
  5. Spending considerable time and effort seeking and using substances or recovering from their effects
  6. Taking substances longer than intended or in larger quantities than intended
  7. Wanting to cut down or quit using a substance but not being successful
  8. Giving up or decreasing participation in important relational, social, and occupational activities because of substance use
  9. Continuing to use substances even with the knowledge it has caused psychological or physical problems or exacerbated underlying conditions
  10. Developing tolerance to the substance. Tolerance develops as a result of the body adapting to chronic substance use to the point where a person needs increasing doses to feel the same desirable effects.
  11. Experiencing withdrawal when someone reduces use or abstains from use of a substance

Symptoms must be present within a 12-month period to meet the criteria for SUD. Please note that the final 2 criteria (tolerance and withdrawal) would not, by themselves, indicate substance use disorder in someone that has been prescribed a medication and is taking it as directed.9

Only physicians and qualified clinicians can diagnose substance use disorders. They use the criteria listed above to make the diagnosis after a thorough assessment.

While not used by clinicians in diagnosing someone with substance use disorders, the following physical, psychological, or behavioral warning signs of addiction may be cause for concern:10

  • Changes in appetite or sleep
  • Weight loss or weight gain
  • A decline in personal hygiene or grooming
  • Changes in friends, activities, and hobbies
  • Unexplained financial problems
  • Legal trouble and physical altercations
  • Changes in attitude and personality
  • Reduction in motivation
  • Sudden mood swings

What Are the Levels of Addiction?

Substance use disorders are categorized as mild, moderate, or severe.9

The levels of addiction are determined by the number of diagnostic criteria present. These levels describe the severity of the substance of use disorder and are usually defined as:9

  • Mild if 2 to 3 criteria are present.
  • Moderate if 4 to 5 criteria are present.
  • Severe if 6 or more criteria are present.

It is important to note that if you think you meet the criteria for a mild SUD, it doesn’t mean you shouldn’t seek help. Without treatment, substance use disorders can persist and lead to increasing negative consequences, up to and including death.2

Learn more on the progression of substance use disorder in our guide to the stages of addiction.

Risk Factors and Causes of Addiction

While there is no single cause for addiction, there are certain risk factors that can increase someone’s risk of developing a substance use disorder.2 Risk factors can stem from:2

  • Having a genetic predisposition to addiction. Researchers believe this accounts for at least half someone’s propensity for developing a substance use disorder.
  • Someone’s upbringing or living environment. Living with people that misuse substances (especially during childhood) has a positive impact on the likelihood of someone developing an addiction themselves.
  • Having a mental health disorder. Around 50% of people that suffer from a form of mental illness will also suffer from addiction and vice versa.11
  • Using substances at an early age.
  • Having a specific method of ingesting the drug (smoking and intravenous drug use, for example, increases a drug’s addictive potential).

Not everyone that has experienced the above risk factors will develop an addiction; however, a person’s likelihood of developing substance use disorder increases with the number of risk factors they have.2

How Addiction Impacts the Brain

Chronic use of drugs and alcohol impacts areas of the brain responsible for motivation, behavior reinforcement, and processing emotions like stress, thinking, problem-solving, forming habits, and even functions that are vital to survival like heart rate and breathing.12 Some changes to the brain may last well after someone quits substance use, which may explain why some people relapse years after getting sober.1

When a person initially uses drugs or alcohol, their goal is not to develop a disorder. While they may consciously choose to take drugs or alcohol at first, as the brain changes from regular use, it becomes increasingly difficult to control.2

Many substances of misuse act either directly or indirectly on the brain’s reward circuit, where dopamine and other important neurotransmitters and brain chemicals not only contribute to  the euphoric “high” associated with substance use but also act to reinforce it.12

Over time, the damage caused to these  areas and structures of the brain has functional consequences and may diminish someone’s ability to feel pleasure and joy from things they once found enjoyable, motivating them to continue using substances despite the detrimental effect on their overall wellbeing.12

The brain also connects environmental cues to drug use, which can be a significant obstacle to someone’s sobriety. Certain areas, smells, people, or situations can trigger cravings in someone that has a substance use disorder.12

Fortunately, there are evidence-based approaches to treatment that can help reverse some of the damage, helping people not only break free from substance dependency, but recognize and avoid triggers, develop healthy coping mechanisms, and repair unhealthy thought and behavioral patterns related to substance use.1

Addiction Treatment Options & Success

Recovery is possible, though it is a complicated process that , for many people, requires professional help.13 This section will provide an overview on the ways in which substance use treatment facilities operate, and things to consider when seeking addiction treatment.

holding hands, productive group therapy session for addiction treatment

No single treatment plan is appropriate for everyone. Effective addiction treatment includes comprehensive individualized care, allowing the patient to safely detox from drugs and alcohol and addressing the numerous factors that contribute to their substance use.1 In addition to the patient’s substance use, an individualized approach also takes into account things like co-occurring disorders, social issues, and vocational needs,

Rehabilitation programs can take place in both outpatient and inpatient rehab settings and typically has multiple components. These programs may use a combination of various behavioral therapies, medication, peer support, and psychoeducation to help patients achieve their goals.1,14

The duration of treatment will also vary per individual, and it is important that a patient remains in treatment for an adequate time in order to meet the goals of their treatment plan. It is not unusual for treatment to evolve, and continual assessments will be made during treatment that may include adjustments as needed.

In 2019, 42% of people 12 years old or older that were enrolled in a treatment program successfully completed treatment, and an additional 21% of discharges were transferred to further substance use programs.15

While relapse prevention is a key part of many rehabilitation programs, relapse after rehab does not necessarily indicate the failure of treatment. For many people, relapse is part of their path to recovery and just means treatment needs to be adjusted.1 It can take multiple attempts for someone to achieve long-term recovery.

If you or a loved one struggles with addiction, please reach out to an American Addiction Centers (AAC) admissions navigator at to learn about our various evidence-based treatment facilities across the United States.

Learn more about addiction with our Addiction 101 Guide.

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