An Overview of Substance Use

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Substance abuse is a pattern of harmful use of any substance for mood-altering purposes. "Substances" can include alcohol and other drugs (illegal or not) as well as some substances that are not drugs at all.

"Abuse" can result from using a substance in a way that is not intended or recommended, or from using more than prescribed. To be clear, someone can use substances and not be addicted or even have a substance use disorder, as defined in the "Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition" (DSM-5).

This article discusses what constitutes harmful substance use, illegal substance use, and prescription drug misuse. It also covers some of the substances that are more frequently abused as well as the risks of substance misuse.

What Is Harmful Use?

Health officials consider substance use as crossing the line into substance abuse if that repeated use causes significant impairment, such as:

  • Disabilities
  • Failure to meet responsibilities
  • Health issues
  • Impaired control
  • Risky use
  • Social issues

In other words, if someone drinks enough to get frequent hangovers; uses enough drugs that they miss work or school; smokes enough marijuana that they have lost friends; or often drinks or uses more than they intended to use, their substance use is probably considered misuse or harmful use. However, there is a broad range of substance abuse in today's society.

Illegal Drug Use

Generally, when people talk about substance abuse, they are referring to the use of illegal drugs. Drugs of abuse do more than alter mood. They can cloud judgment, distort perceptions, and alter reaction times, all of which can increase the risk of accident and injury.

These drugs got to be illegal in the first place because they are potentially addictive or can cause severe negative health effects. Some believe that any use of illegal substances is dangerous and, therefore, abusive.

In the United States, the most commonly used illegal drugs, in order, are:


Substance abuse usually refers to the use of illegal drugs such as cocaine, heroin, and methamphetamine. These substance are illegal because of their high risk for abuse and dangerous side effects.

Recreational Drug Use

Some people argue that casual, occasional use of some drugs is not harmful and is merely use, not abuse. The most vocal of the proponents of recreational drug use are those who smoke marijuana. They argue that marijuana is not addictive and has many beneficial qualities, unlike the "harder" drugs.

But recent research has shown that even marijuana may have more harmful physical, mental, and psychomotor effects than first believed. Each year, new scientific studies find more ways that long-term marijuana use is harmful to your health.

In addition, the National Institute on Drug Abuse (NIDA) reports that people who use marijuana can become psychologically dependent, and therefore addicted. NIDA estimates that 9% of people who use marijuana will become dependent, and the percentage rises to 17% for those who began using the drug in their teens.

Prescription Substance Misuse

Prescription substance misuse has risen substantially over the last few decades. The National Institute on Drug Abuse estimates that between 8% to 12% of U.S. patients who are prescribed opioid pain relievers develop a substance use disorder.

According to the Centers for Disease Control and Prevention (CDC), the number of opioid-related deaths increased by 5% between 2018 and 2019, with an average of 38 people dying each day from prescription opioid overdoses in 2019.

In the U.S., there are three main classes of prescription drugs commonly misused: Opioids, central nervous system depressants, and stimulants. These include:


Substance abuse can also involve misusing prescription medications that have the potential for dependence.

Other Commonly Abused Substances

Alcohol, prescription, and over-the-counter medications, inhalants and solvents, and even coffee and cigarettes can all be used to harmful excess. Many children have their first encounter with substance abuse by using inhalants, simply because they are found in many common household products and, therefore, readily available.


Alcohol is legal for adults over the age of 21 in the United States, and there is nothing wrong with having a couple of drinks with friends or to unwind on occasion. But, it doesn't take much alcohol to reach a harmful level of drinking, and that is when alcohol use can turn into alcohol abuse.

Drinking five or more drinks for men (four for women) in any one sitting is considered binge drinking, which can be harmful to your physical and mental health in many different ways.


Nicotine is the single most abused substance in the world. Although smoking has declined in recent years, it is estimated that 40 million Americans are still addicted to nicotine in spite of its well-publicized harmful effects.

Again, just because it is legal, doesn't mean it can't be abused. The fact that the negative health effects of nicotine take a long time to manifest probably plays a role in the widespread abuse of tobacco.


Whereas nicotine is the most abused drug, caffeine is the most commonly used mood-altering drug in the world. And yes, too much caffeine can be harmful to your health.

Studies have also found a link between caffeine use and several psychiatric syndromes, including caffeine-induced sleep disorder and caffeine-induced anxiety disorder. People diagnosed with generalized anxiety disorder, panic disorder, primary insomnia, and gastroesophageal reflux are usually advised to reduce or eliminate regular caffeine use.


So-called "designer drugs" and synthetic drugs, such as bath salts and synthetic marijuana, are not (yet) illegal, but can be abused and can possibly be more dangerous than other drugs.

Other designer drugs that are commonly misused include:

  • Amphetamines
  • Ecstasy
  • LSD
  • GHB
  • Ketamine
  • Rohypnol (date rape drugs)
  • PCP

Anabolic Steroids

Anabolic steroids have no mood-altering or intoxicating properties, but they can still be misused. Using anabolic steroids to enhance performance or develop muscles and strength is abusive because of the negative side effects of steroid use. These can range from merely annoying to life-threatening in some cases. If using a substance can cause you harm, it is substance abuse. Theoretically, almost any substance can be abused.


Substance abuse often involves substances including alcohol, nicotine, caffeine, synthetic drugs, and anabolic steroids. 

Risks of Substance Misuse

When society determine that using certain substances is harmful, it places legal prohibitions on their use. This is to both protect individuals' wellbeing and shield society from the costs involved with related healthcare resources, lost productivity, the spread of diseases, crime, and an increased risk of homelessness (although the impact of criminalization has been open to considerable controversy).

For many legal substances, the line between use and abuse is not clear. Is having a couple of drinks every day after work to unwind use or abuse? Is drinking two pots of coffee in the morning to get your day started use or abuse? Is smoking a pack of cigarettes a day substance abuse?

Generally, in these situations, only the individual can determine where use ends and abuse begins. The question to ask is whether the use is causing harm or resulting in:

  • Physical health problems: Substance abuse can increase the risk of physical health issues including heart disease, stroke, and cancer.
  • Mental health problems: Substance use often co-occurs with mental health problems, but it can also worsen or contribute to the onset of some conditions as well.  
  • Risky or dangerous behavior: Substance use can increase the risk of risky behaviors, such as driving while intoxicated and engaging in unprotected sex.
  • Legal risks: Using illegal substances means an increased risk of legal consequences, which can include arrest and incarceration.


Substance abuse poses both individual and societal risks. For individuals, it can lead to health problems, mental health issues, risky behavior, and legal problems. For societies, substance abuse can increase the costs associated with health problems and lost productivity. It can also contribute to social problems such as crime.

A Word From Verywell

Has your substance use become harmful? If you think this may be true for you, you are certainly not alone. According to the latest estimates, about 27.1 million Americans—approximately one in every 10 people—misuse substances.

Are you hesitant to seek help for your substance use? Again, you are not alone. In 2015, an estimated 21.7 million people needed substance use treatment, but only three million actually received any treatment. If you have tried to quit or cut back on your own and found you were not able to do so, you may want to try other options and learn more about treatment for substance abuse.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

Frequently Asked Questions

  • What is substance abuse?

    The most common definition is a pattern of harmful use of any substance for mood-altering purposes. Substances can include alcohol, prescription and over-the-counter drugs, illegal drugs, inhalants and solvents, nicotine, and even coffee.

  • What is a substance use disorder?

    The DSM-5 recognizes substance-related disorders resulting from the use of 10 separate classes of drugs: alcohol; caffeine; cannabis; hallucinogens (phencyclidine or similarly acting arylcyclohexylamines, and other hallucinogens, such as LSD); inhalants; opioids; sedatives, hypnotics, or anxiolytics; stimulants (including amphetamine-type substances, cocaine, and other stimulants); tobacco; and other or unknown substances.

    Substance use disorders span a wide variety of problems arising from substance use and cover 11 different criteria.

  • What causes substance abuse?

    Substance abuse is a complex problem that is influenced by a number of factors. There is no way to predict who will become addicted to drugs, but a combination of influences can increase a person's risk of developing an addiction. Genes, the presence of other mental health conditions, developmental factors, and environmental influences all play a role. 

  • How can people prevent substance abuse?

    Family history, peer pressure, and recreational drug use are all risk factors for substance abuse. Being aware of these risks can help you take steps to avoid using substances in the first place. Seeking treatment for mental health conditions can also play a role in prevention. If you use substances for recreational purposes, misuse prescription medications, or take substances for the purposes of becoming intoxicated, talk to your doctor about your treatment options.

  • How is substance use treated?

    Treatment for substance abuse may involve behavioral therapies, medications, or a combination of different approaches. Cognitive behavioral therapy (CBT), contingency management, and motivational enhancement therapy are a few types of therapy that may be used. Medications are also available that can help people with opioid, nicotine, or alcohol addiction.

14 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Buddy T
Buddy T is an anonymous writer and founding member of the Online Al-Anon Outreach Committee with decades of experience writing about alcoholism.