Addiction is a complex medical condition that is characterized by the compulsive use of harmful substances despite negative consequences.[1] Addiction is a severe form of a substance use disorder. People can develop an addiction to various illegal drugs, such as cocaine, heroin, and ecstasy, as well as prescription medications like opioid pain killers, tranquilizers (sleeping pills), and prescription stimulants. Alcohol, marijuana, and nicotine are also addictive substances and can lead to substance use disorders.

What ends up as an addiction may have started with the experimental use of recreational drugs in social situations. For some people, it stops there. For others, drug use continues and the frequency or quantity of drug use increases over time. As time goes on, the person may need larger doses of the drug to get the same effects of the drug (this is called tolerance). They may find it difficult to go on without the drug. At this stage, attempts to quit using may cause intense cravings and make the person physically ill with uncomfortable symptoms (called withdrawal symptoms). Physical and psychological dependence on the drug and fear of withdrawal symptoms can drive a person with a substance use disorder to continue using.

What is Addiction?

People with severe substance use disorders (drug addiction or alcoholism) can be intensely focused on obtaining and using the substance to the point that it consumes their life. The continued use of harmful drugs and alcohol, despite knowing that it will cause (or has caused) all kinds of problems, is a characteristic feature of addiction. Professional treatment at a drug rehab facility is often required to help people with substance use disorders recover from addiction.

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) specifies [2] that the diagnosis of a substance use disorder requires that the person has presented with at least two of the following diagnostic criteria within the last 12 months, and that the person has also suffered distress or impairment owing to the use.

  1. Using a substance in larger amounts or for a longer time period than desired
  2. Unable to cut down despite wanting to do so
  3. Spending lots of time each day obtaining the substance, consuming the substance, or recuperating from use
  4. Experience of cravings or urges
  5. Failure to meet social or professional obligations, with substance use being responsible in whole or in part
  6. Usage continues in spite of recognition from the user that it is leading to professional, social, or family issues
  7. Stopping or cutting back on professional, social, or family activities as a result of use
  8. Using in physically threatening environments, or usage causing harm in a mental or physical sense
  9. Persistent use despite knowing the substance is contributing to or causing a problem (physically or mentally)
  10. Tolerance such that increasing amounts of a substance are needed to get the desired effect
  11. Physical withdrawal effects or symptoms are felt as the quantity of the substance in the body decreases

Addiction Statistics in the United States

Adolescents and young adults are the future of the country, and drug and alcohol addiction in this age group are particularly concerning. Monitoring the Future is an annual survey of teenagers in the U.S. to measure use of drugs, alcohol, and nicotine among young people. In 2019, over 42,000 students participated in the survey. [3] More than half of all 12th graders reported alcohol use in the past year. Roughly 38% reported use of any illicit drug, with marijuana being the most commonly used drug (36%). More than 6% of 12th graders reported daily marijuana use. There is some good news, however. Prescription drug misuse (Vicodin, OxyContin) among teenagers had risen to worrisome levels in 2003, with about 10% of 12th graders reporting Vicodin use within the past year. In 2019, this number had fallen to around 1%. Similarly, use of Adderall (a prescription stimulant) among teenagers has improved from about 7% in 2014 to less than 4% in 2019.

Addiction puts people at risk of drug overdose deaths. Drug overdoses are the leading cause of injury-related preventable deaths in the United States. More than 70,000 Americans died of drug overdoses in 2017 alone.[4] According to the Surgeon General of the United States, one in seven Americans is battling substance use disorders, but only 10% receive the necessary treatment.[5] In the United States, the use of tobacco, alcohol, and illicit drugs results in estimated costs of over $700 billion annually. These costs come in the form of lost work productivity, health care, and crime. [6]

Addiction and the Human Brain

Addiction is a chronic, relapsing disorder that involves physical and psychological dependence on drugs or alcohol. People with addiction may pursue the habit even to the point of putting themselves and their loved ones in harm’s way. Many people with substance use disorders are aware they have a problem but cannot stop alcohol or drug use. Why do some people struggle with quitting drugs or alcohol? The answer lies in the science of addiction and the chemistry of the addicted brain.

Different drugs have distinct patterns of addiction, and the severity varies with dose and length of use. Addiction affects many organs in the body but has a particularly notable impact on the brain. As the addiction to drugs or alcohol progresses over time, changes occur in the brain chemistry and brain circuitry of the user.

When a person first begins using a drug, the brain is flooded with feel-good chemicals such as dopamine, which activate the brain’s natural reward system. This results in the person’s desire to continue using the drug to achieve positive effects. However, with repeated use of the drug, there is a decrease in functioning of the brain’s dopamine system, as well as other changes in brain chemistry. This can result in feelings of distress when the person does not have the drug in their body (when they are in withdrawal). The person learns that, to alleviate symptoms of withdrawal, they just need to consume more of the drug. This can become a vicious cycle: the person feels great from the drug, then feels horrible when they do not have the drug, so the brain learns to get more of the drug. [7] Eventually, additional brain changes can even further decrease someone’s ability to resist strong cravings for the drug. It is these changes in the brain that cause an addiction to spiral out of control. [8]

Risk Factors and Causes of Drug and Alcohol Addiction

Millions of people are exposed to addictive substances every year, but the vast majority do not develop an addiction. What makes some people more likely to experiment with illegal drugs and progress toward a harmful pattern of use? Addiction is a disease, and like many diseases, several factors contribute to its development. The factors that lead to alcohol and drug addiction are broadly classified as environmental and genetic factors.

Studies in adoptive and twin families show that genetics plays a major role in the development of substance use disorders. In other words, addiction tends to run in families. This does not necessarily mean someone is “doomed” to a fate of addiction if a family member has suffered from addiction. However, if a person has a first-degree relative (e.g., parent, sibling) with a drug or alcohol addiction, they are at greater risk of developing an addiction themselves. For example, scientists have identified genes which increase the risk of smoking in adolescents by threefold. [9]

Also, studies show there can be an overlap in genetic influences for various types of addictions, for example, alcoholism and illicit drug dependence. A family history of one type of addiction, therefore, can predispose a person to develop another type of addiction.

However, genetics are not the only factors that influence drug and alcohol abuse. A few other individual characteristics that increase risk include:

  • Psychiatric conditions like conduct disorder, depression, anxiety, and attention deficit hyperactivity disorder (ADHD) increase the risk of developing problematic substance abuse and addiction. Using drugs can become a way of coping with the painful emotions associated with these disorders.
  • The earlier in life a person first uses alcohol or drugs, the higher is the risk of developing drug dependence later in life [10]
  • Sexual minority individuals (LGBTQ) are more likely to suffer from addiction compared to heterosexual (i.e., straight) individuals. [11]

Environmental factors also play a key role in why some people struggle with addiction and others do not. Some of the environmental factors that can increase the likelihood of substance use and ultimately addiction include:

  • Easy availability of drugs and alcohol
  • Social pressure that is either direct (e.g., peer pressure, especially in youth) or indirect (e.g., what seems “normative” among peers)
  • Exposure to trauma, adversity, or difficult life situations
  • Lack of social support
  • Family dynamics (e.g., lack of parental supervision in teenagers)
  • Socioeconomic status
  • Type of drug used (some drugs, such as cocaine and opioid painkillers, are highly addictive and can result in more rapid development of dependence than other drugs like marijuana).

If you look at the list above, it becomes clear why so many rock stars and celebrities battle addiction. They have no shortage of money, easy access to drugs, grueling schedules, constant pressure to succeed, and a culture that encourages substance use, all of which combine to form a cocktail of addiction that sometimes proves deadly.

Recognizing Addiction in a Loved One

When a person is in the grips of severe alcohol or drug addiction, they may be unable to help themselves. It is often the responsibility of family members and friends to spot addiction in a loved one. Recognizing addiction is an important first step in getting the affected person the help they need to recover. Possible signs and symptoms that a loved one may be suffering from a substance use disorder include:

  • Poor performance at work or school, such as missed deadlines, incomplete assignments, a drop in grades, or job loss.
  • A lack of interest in previously enjoyed hobbies
  • Neglecting relationships, or having problems in relationships because of substance use
  • Taking unnecessary risks
  • Physical withdrawal symptoms like sweating, trembling, or vomiting, when the person does not have the substance
  • Increased tolerance to the substance (needing more to get the same effect)

Identifying drug or alcohol abuse early allows the person to get help before the potentially irreversible consequences of addiction occur, such as acquiring an infection like HIV through shared needles, losing employment, permanently damaging relationships, getting arrested or incarcerated, damaging one’s reputation, or losing custody of a child. With time, family and children of a person suffering from addiction can become severely impacted by the behavior. [12]

Common Addictions in the United States

Addiction impacts the lives of millions of Americans and claims thousands of lives each year. According to SAMHSA, nearly 165 million people in the US used substances (tobacco, alcohol, or illicit drugs) within the past month, and about 20 million had a substance use disorder related to their use of alcohol or illicit drugs. [13] Some addictions are more common and more deadly than others. Here are some of the most common substances to which people in the United States are addicted.


Approximately 140 million Americans report alcohol use within the past month. About 67 million are binge drinkers, defined by 5+ drinks (for men) or 4+ drinks (for women) on the same occasion on at least 1 day in the past 30 days. Moreover, close to 17 million are heavy drinkers (reporting 5 or more days with binge drinking events, in the past 30 days). [14] Alcoholism claims 93,000 lives each year in the U.S. [15] It affects people across age, gender, race, and socioeconomic status. Excessive use of alcohol is linked to more than 200 diseases and injury conditions, which affects almost 15 million Americans. It can affect the brain, heart, liver, and pancreas, cause many types of cancers, and weaken the immune system. While the prevalence of alcohol use disorder is higher in men, women are at greater risk of severe brain and other organ damage from alcohol addiction. [16]


In 2018, about 60 million Americans used a tobacco product in the past month, and 47 million of those reported smoking cigarettes in particular. An estimated 672,000 adolescents (aged 12–17) reported smoking cigarettes within the past month. [17] Tobacco products are easily available and contain as many as 5,000 chemicals, dozens of which have been linked to heart disease, lung disease, and cancer. Globally, an estimated one quarter of the world’s adult population smokes daily. [18] Smoking accounts for 30% of all cancer deaths and 87% of lung cancer deaths. [19] Despite the dangers of cigarette smoking, the tobacco lobby in the United States is a powerful political force and works behind the scenes to advance a pro-tobacco agenda, so that tobacco products can be sold to the American public without hindrance from lawmakers.

standing cigarette burning out


The National Survey on Drug Use and Health (NSDUH) in 2018 found that more than 43 million Americans had used marijuana in the past year, corresponding to nearly 16% of the population. The legalization of recreational marijuana use in the US was kicked off by Colorado in 2012. As of mid-2020, it was legal to buy and consume marijuana recreationally in 11 US states plus D.C. Despite the increasing legalization by more and more US states, marijuana has many short- and long-term effects on the human brain. [20] The active psychotropic ingredient in marijuana, THC, can alter senses, change mood, and impair memory and thinking. High doses of marijuana can cause hallucinations, delusions, and psychosis.

Prescription Opioids

Opiate abuse has increased dramatically in the United States over the past couple of decades. Based on SAMHSA estimates in 2018, approximately 10 million people in the US misused prescription pain relievers, such as Vicodin, Percocet, and OxyContin, within the past year. The number of prescriptions written for opioid pain pills in the U.S. increased from 76 million in 1991 to 219 million in 2011. These powerful drugs work by blocking pain signals and releasing large amounts of dopamine in the human brain. Repeated misuse of prescription pain relievers can lead to addiction, which is associated with a variety of health complications. [21]

Although methadone and suboxone are often used to treat serious addictions, they can also be addictive if misused.


Benzodiazepines (benzos) are a class of drugs used to treat panic attacks, depression, anxiety, insomnia, and seizures. Most people who are prescribed benzos take them as directed, but some people misuse these drugs and develop an addiction to them. An estimated 5.4 million Americans misused prescription benzodiazepines in the past year, including nearly 400,000 adolescents (aged 12–17), according to SAMHSA’s 2018 survey. Benzodiazepine abuse often occurs as part of polysubstance abuse, where benzos are used to enhance the effects of other drugs, putting the users at risk of drug overdose and death.[22] Despite the risks of misuse and addiction, benzos continue to play an important role in pharmacotherapy for anxiety disorders. 


Cocaine is a highly addictive stimulant drug that is sold on the street as crack, snow, rock, coke, and blow. According to SAMHSA, an estimated 5.5 million Americans are past-year users of cocaine, including 112,000 adolescents (aged 12–17). Cocaine floods the human brain with dopamine[23], leading to feelings of extreme happiness and energy. However, long-term use of cocaine is associated with several health effects and the risk of overdose and death. Street dealers often mix cocaine with harmful substances to increase profits, putting the lives of cocaine users at risk. People who are addicted to cocaine need stronger and more frequent doses of the drug over time to feel the same high. They experience uncomfortable withdrawal symptoms if they decrease or stop cocaine use. Treatment at a drug rehab facility is recommended to recover from addiction to cocaine (including crack cocaine).

Prescription Stimulants

Prescription stimulants, such as Adderall, Ritalin, Concerta, and Dexedrine, are medications used to treat conditions like attention deficit hyperactivity disorder (ADHD) and narcolepsy (uncontrolled excessive sleepiness). [24] The National Survey on Drug Use and Health (NSDUH) in 2018 found that roughly 5 million people in America reported past-year misuse of prescription stimulants, including nearly 400,000 adolescents aged 12–17. College students and busy professionals sometimes misuse prescription stimulants to improve performance through increased alertness, energy, and attention. Popular slang words for these drugs are uppers, speed, and vitamin R. Misuse of prescription stimulants can lead to harmful health effects, including heart problems, psychosis, and addiction.


Ecstasy (MDMA or Molly) is a hallucinogenic drug that produces feelings of warmth, pleasure, and energy, along with a distortion in the perception of time and senses. Other hallucinogens include LSD, PCP, peyote, mescaline, psilocybin mushrooms, ketamine, and DMT. An estimated 5.6 million Americans, or 2% of the population, reported past-year hallucinogen use on the 2018 NSDUH survey. MDMA (ecstasy) was initially a popular party drug but is now abused by a broader demographic of Americans. Commonly called Molly, ecstasy increases the activity of brain chemicals, dopamine, serotonin, and norepinephrine, which are associated with pleasure, elevated mood, and reward. However, MDMA can affect the body’s temperature regulation system and damage the kidneys, liver, and heart, sometimes even leading to death.[25]


Heroin is an opioid drug made from the seeds of the opium poppy plant. It is sold on the street as big H, smack, hell dust, and horse. The 2018 SAMHSA survey found that an estimated 800,000 Americans used heroin in the past year. Heroin is misused because it binds to opioid receptors in the human brain and produces temporary feelings of euphoria. However, long-term heroin use can lead to addiction and a variety of health effects. Drug dealers often cut heroin with additives to increase its street value, which can prove dangerous for users. If a person overdoses on heroin, it can lead to a life-threatening slowing down of breathing, coma, permanent brain damage, and even death.[26]


Methamphetamine (meth, crystal meth) is a powerful and highly addictive stimulant drug that is abused by smoking, snorting, swallowing, and injecting. In 2018, approximately 1.9 million Americans reported using methamphetamine in the past year. Methamphetamine causes a rapid release of large amounts of dopamine in the brain, leading to a temporary rush or high.[27] However, long-term meth abuse is linked to several health complications. Meth is often manufactured in small, illegal, often makeshift labs with relatively inexpensive ingredients like pseudoephedrine (which is found in cold medications). Drug production in these clandestine meth labs releases dangerous fumes into the air and can result in deadly explosions and fires.

Dangers of Addiction

The short- and long-term health effects of addiction to alcohol and illicit drugs are significant. Addiction can cause irreparable damage to various organ systems in the human body. Highly addictive drugs can induce psychotic behavior, seizures, coma, and death due to overdose. Long-term use can lead to permanent brain damage. Moreover, street drugs often contain unknown substances that can be harmful to users. Contamination during illegal manufacture of drugs can also put the lives of drug users at risk. In addition to the physical and mental health effects, drug and alcohol addiction can lead to various life-changing complications, including:

  • Intravenous drug users can acquire infectious diseases like HIV and hepatitis B and C through shared needles.
  • People who use illicit drugs or excessive alcohol are at risk of accidents and injuries, for example, from driving under the influence or doing other dangerous activities while intoxicated.
  • People with drug or alcohol abuse and addiction attempt suicide nearly six times more than people who do not have a substance use disorder.[28]
  • Addiction to drugs and alcohol can affect every aspect of a person’s life, including relationships. Alcohol and drug abuse can lead to family problems, marital conflict, divorce, and child custody issues.
  • Drug addiction can lead to problems at work or school, with loss of employment or poor academic performance.
  • Legal problems are common among people battling alcohol use disorder or drug addiction. Such problems may arise from buying illegal substances, stealing to support the habit, driving under the influence, and other illegal behaviors.
  • Financial difficulties in addicts can stem from spending money to procure drugs or alcohol to the point of neglecting other needs and leading to debt.

The good news is that drug and alcohol addiction is preventable and treatable. Alcohol should be consumed in moderation. Prescription medications should always be taken exactly as prescribed by a physician. And family members and friends should be vigilant for signs of illegal drug and alcohol addiction in their loved ones.

Last updated: March 9, 2023


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