Substance Type

Substance Type

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Substance Use Disorder

What is Substance Use Disorder (SUD)?

Substance Use Disorder, or SUD, is the clinical name for the wide range of chronic diseases often referred to as addiction. SUD can be categorized as mild, moderate, or severe and specified to the type of substance a person is using. For example people who have a Substance Use Disorder around opioids are also referred to as having an opioid use disorder or OUD.

According to the National Institute on Drug Abuse (NIDA), addiction is a chronic, relapsing brain disease that develops in response to the use of an addictive substance. Symptoms include impaired control, social impairment, risky use, increased tolerance, and withdrawal. Drugs change the structure and functioning of the brain, impairing the part of the brain in charge of impulse control.

We tend to use Substance Use Disorder, Opioid Use Disorder, SUD, and OUD instead of addiction on our site since the term “addiction” can be stigmatizing and prevent people from engaging with proper treatment and other resources.

What is physical dependence?

Physical dependence can happen with the chronic use of many drugs including opioids like heroin, fentanyl, oxycodone, and hydrocodone. Prescription opioids can lead to physical dependence even if taken as instructed. When drugs such as opioids are stopped suddenly, withdrawal symptoms develop. With opioids, withdrawal symptoms include tearing up, runny nose, sweating, restlessness, nausea, vomiting, and diarrhea. Many describe withdrawal as the worst flu of their life.

Can SUD be treated?

Yes. Addiction/SUD is a chronic disease that can be treated and managed successfully by the use of behavioral therapy and/or medications such as methadone, buprenorphine, and naltrexone. Research shows that a combination of behavioral therapy plus medication is the most successful form of treatment.

Due to the chronic nature of addiction, relapses happen. However, this does not necessarily mean that treatment has failed, rather that treatment needs to be adjusted or reinstated. This is similar to relapses in other chronic diseases such as diabetes or hypertension which have a complex set of physiological and psychological factors that could lead to relapse.

Resources to learn more


According to the, National Institute of Drug Abuse, Addiction is a chronic disease characterized by drug seeking and use that is compulsive, or difficult to control, despite harmful consequences. Addiction can cause a physical or psychological dependence on a substance and many substances can cause an addiction, including alcohol, prescription medications and illicit drugs.

The initial decision to take drugs is voluntary for most people, but repeated drug use can lead to brain changes that challenge an addicted person’s self-control and interfere with their ability to resist intense urges to take drugs. These brain changes can be persistent, which is why drug addiction is considered a “relapsing” disease—people in recovery from drug use disorders are at increased risk for returning to drug use even after years of not taking the drug.


Alcohol is the most widely abused substance across most of the world, including in the United States. Legal to some extent in all 50 states, alcohol impacts numerous body systems, which in turn causes numerous effects in users. Alcohol creates feelings of euphoria and lowers inhibitions, but it also severely impairs judgment, perception, and reaction times. Alcohol is a central nervous system depressant, but it causes the most severe long-term damage to the liver.

There are many forms of alcohol, including:

  • Beer
  • Wine
  • Liquor


Barbiturates act on the central nervous system by slowing down its functioning. Barbiturates are derivatives of the chemical barbituric acid. Barbiturates were historically popular for the treatment of psychiatric and sleep disorders, and they are still used for anesthesia and treatment of a number of conditions such as epilepsy and headaches. Barbiturates are highly addictive, and they present a very high overdose risk as they cause many body systems to shut down.

Examples of barbiturates include:


Benzodiazepines, or Benzos, are a class of drugs that function by interacting with the neurotransmitter gamma-aminobutyric acid-A (GABA-A). Each Benzo interacts with GABA-A differently, which is why each Benzo impacts the body and mind differently. Benzos are prescribed to treat a wide variety of psychiatric and sleep conditions, but they are very commonly abused. Benzos are highly addictive, and can cause numerous medical and psychiatric problems when not used as intended.

Examples of Benzos include:

Additional Resources


Cannabinoids are a class of drugs that are chemically similar to tetrahydrocannabinol (THC), the active agent in marijuana. Cannabinoids create feelings of elation, known as a high, but they also negatively impact mental and physical functioning. Cannabinoids are the most widely abused drugs after alcohol, and they are increasingly gaining legal acceptance. Although considered less addictive than other drug classifications, cannabinoids can seriously damage a person’s mental and physical health.

Examples of cannabinoids include:

Additional Resources


Also called opiates, opioids are derived from either the drug opium or chemicals designed to mimic it. Opioids work by interacting with neurotransmitters in the brain and blocking the signals that they are sending. This enables opioids to serve as powerful pain killers, but it also can cause feelings of intense pleasure, leading to addiction. Opioid addiction is one of the most serious problems faced by America today. Opioids are some of the most addictive of all known substances, and they are some of the deadliest.

Some of the most well known opioids include:

  • Heroin
  • Fentanyl
  • Oxycodone

Additional Resources

Other Drugs


Hallucinogens, sometimes referred to as dissociatives, alter the user’s perception of reality, often resulting in auditory and visual hallucinations, a process known as “tripping.” Although hallucinogens are generally less addictive than other drug classifications, their immediate impacts are generally more severe and dangerous.

Examples of hallucinogens include:

  • LSD
  • Psychedelic Mushrooms
  • PCP


Also known as, “uppers,” the primary use of stimulants is to increase energy, concentration, and wakefulness. Stimulants are said to provide a “rush.” In the short term, stimulants are believed to increase productivity and performance, while producing an excited high of pleasure. In the long term, stimulants are incredibly addictive and have a very high potential for abuse.

Examples of stimulants include:

  • Adderall
  • Amphetamines (Meth)
  • Cocaine
  • Ecstasy (MDMA)

These drugs increase alertness and heart rate, producing an effect of increased confidence, and energy. Large doses of these drugs can result in anxiety, panic, seizures, headaches, stomach cramps, aggression and paranoia.


Depressants, or also commonly known as “downers”, cause feelings of relaxation and tiredness by slowing the central nervous system to produce a calming effect. While many serve legitimate purposes in the fight against mental illness and sleep deprivation, they are very commonly abused because they may also create feelings of euphoria. Depressants are not only some of the most highly addictive drugs, but they are also some of the most highly dangerous and likely to cause overdose.

Examples of depressants include:

  • Alcohol
  • Opiates
  • Benzodiazepines
  • Barbiturates

Some of these substances are often prescribed to relieve pain, help you sleep or in the case of alcohol, used recreationally when socializing. However, when taken in excessive amounts or in combinations with other drugs, depressants can depress normal functions such as breathing and heart rate until they eventually stop, resulting in brain damage or death.


Inhalants are a vast range of chemicals that are ingested primarily by breathing them in, or huffing. Most inhalants are commonly used materials that are in no way designed to be ingested by humans. While there is incredible variety between inhalants, most produce feelings of a high. Inhalants are less studied than most other drugs. While they tend to be less addictive than many other substances, the use of inhalants is incredibly dangerous and causes many serious health effects.

Examples of commonly abused inhalants include:

  • Paint thinner
  • Nail polish remover
  • Gasoline
  • Air duster

Tobacco and Nicotine

According to the CDC, tobacco use is the leading cause of preventable disease, disability, and death every day in the United States. Cigarette smoking causes more than 480,000 deaths in the US each year and increases health risks for stroke and coronary heart disease by to 2-4 times. In addition to these effects, smoking harms nearly every organ of the body and affects a person’s overall health.

Tobacco & Nicotine come in many forms as such as:

  • Cigarettes
  • Cigars, Cigarillos
  • Electronic Cigarettes (vape pens, Juuls, etc.)
  • Smokeless Tobacco (chewing tobacco, snus, snuff, etc.)
  • Waterpipes (Hookah, Shisha)

As of 2017, about 34 million US adults smoke cigarettes. Every day approximately 2,000 people under the age of 18 smoke their first cigarette, with more than 300 becoming daily cigarette smokers. Currently, the CDC’s National Tobacco Control Program is the only nationwide prevention program however; Indiana has launched the Tobacco Quitline recognizing the importance of reducing secondhand smoke.

Additional Resources:

Youth and Parents

This page provides several useful websites and resources for parents and teens that want to learn more about substances and addiction. For more information about these sources contact Diamond Justus at


Last Updated: April 2024