Drug addiction is challenging but treatable. According to the American Society of Addiction Medicine, it involves connections between brain circuits, heredity, the environment, and a person’s life experiences.1 The fact that people continue to use substances despite the adverse effects on their lives is a defining characteristic.
Drug addiction affects all parts of a person’s life and is indiscriminate in its reach. It impacts mental and physical health and can destroy personal relationships and careers. Ultimately, it can result in losing everything a person holds dear and, in some cases, death.
Many studies aim to understand why people become addicted to drugs. Traditionally, addiction has been viewed as a disease, with recovery being a lifelong process. More recently, neuroscientists and health professionals have focused on a person’s past traumatic events as a cause of addiction. Many addiction treatment programs aim to address past trauma and the root cause of addiction, and, in doing so, it is possible to overcome both simultaneously.
Identifying the causes of addiction helps to determine prevention strategies and effective treatment plans. Some individuals falsely assume that those with a drug dependency continue to use substances due to a lack of willpower or motivation to stop. In reality, drug use can lead to brain changes that interfere with a person’s self-control and ability to resist the urge to use drugs.2
The good news is that regardless of the reason why you are addicted, substance addiction rehabilitation programs are widely accessible. Long-term recovery is possible for everyone through effective addiction treatment.
How Widespread Is Substance Abuse?
Drug addiction is one of the most common public health problems in the United States and worldwide. Tens of millions of Americans meet the diagnostic criteria for a substance use disorder each year, and overdose remains a leading cause of preventable death, though recent data shows significant improvement.
316 Million People Worldwide
In 2025, 316 million people worldwide between the ages of 15 to 64 used drugs.
48.4 Million People in the U.S.
An estimated 48.4 million Americans age 12 or older (16.8% of the population) qualified as having a substance use disorder in 2024.
The scope of the problem is large and still growing in many parts of the world. The UNODC World Drug Report 2025 found that approximately 316 million people aged 15 to 64 used drugs, representing nearly 6% of the global population in that age range. That number is up more than 20% since 2013.3
In the United States, the 2024 National Survey on Drug Use and Health (NSDUH) found that 48.4 million people aged 12 or older, or 16.8% of that population, had a past-year substance use disorder.4 Of the 52.6 million people classified as needing substance use treatment, only about 10.2 million received it.
On overdose deaths: the CDC reported that 79,384 people in the United States died from drug overdose in 2024, a 26.2% decrease from 2023.5 This was the largest single-year decline ever recorded, though overdose remains a leading cause of injury death for adults.
The Most Common Drugs That Lead to Addiction
Both legal and illegal substances carry a risk of addiction. The most commonly misused categories include opioids, stimulants, depressants (such as alcohol, benzodiazepines, and sedatives), hallucinogens, nicotine, and marijuana. Any drug that activates the brain’s reward system has the potential to create a cycle of compulsive use.
A European study that evaluated 20 commonly available substances against criteria including injury, crime, economic cost, loss of relationships, and drug-related mortality identified alcohol, heroin, and crack cocaine as the most harmful.6
Some of the most commonly used and addictive substances are described below.
Heroin
Heroin is an opioid that produces an immediate rush of pleasure. Research estimates that roughly 23% of people who use heroin will develop an opioid use disorder. Withdrawal is extremely unpleasant, with symptoms including diarrhea, vomiting, severe pain, and uncontrollable shaking, which makes stopping without medical help very difficult.
Cocaine
Cocaine is a stimulant derived from coca leaves. It increases dopamine in the brain, producing a short-lived but intense high. As tolerance develops, people take more to reach the same effect, raising the risk of overdose. Long-term cocaine use can lead to nosebleeds, depression, abnormal heart rhythms, insomnia, and loss of smell. The CDC reported broad declines in cocaine-involved overdose deaths in 2024 as part of a nationwide reduction in drug overdose fatalities.
Alcohol
In the 2024 NSDUH, 9.7% of Americans aged 12 or older had an alcohol use disorder in the past year. Because alcohol is legal and widely available, its risks are not always recognized the way illicit drugs are. Excessive drinking alters the brain’s chemical balance and increases the likelihood of dependence over time.
The health consequences of heavy alcohol use include stroke, high blood pressure, depression, liver failure, and several forms of cancer.
Prescription Painkillers
Painkillers are the most commonly misused class of prescription medication. This category includes hydrocodone, tramadol, oxycodone, codeine, morphine, hydromorphone, and fentanyl. They produce a relaxing high and are frequently taken for non-medical purposes. According to the 2024 NSDUH, 7.6 million people aged 12 or older misused prescription opioids in the past year.
Side effects of prescription painkiller misuse include drowsiness, nausea, constipation, muscle pain, and intense cravings.
Methadone and Buprenorphine
Used as treatments for opioid use disorder, methadone and buprenorphine are themselves opioids and carry a risk of misuse. When taken as prescribed, methadone can reduce cravings for heroin and other opioids. But the high potency of each dose means that taking too much at once can lead to overdose or death.
Side effects of both medications include nausea, vomiting, dizziness, fatigue, and constipation.
Benzodiazepines
Benzodiazepines (often called benzos) are sedative-hypnotics with tranquilizing effects. Common examples include Valium (diazepam) and Xanax (alprazolam). They are prescribed to treat anxiety, seizures, and alcohol withdrawal, but are frequently misused. The 2024 NSDUH now tracks benzodiazepine misuse as a distinct category, reflecting ongoing federal concern about the scope of the problem.
The most common side effect is drowsiness. Others include impaired memory, slow pulse, confusion, heavy sedation, and a decline in cognitive function.
Amphetamines
Amphetamines are prescribed for ADHD and other conditions. Adderall and other prescription amphetamines can be misused and lead to addiction. Methamphetamine (meth) is an illegally manufactured form that produces an immediate, intense euphoria and is extremely addictive. Overdose deaths involving meth rose sharply from 2011 through the early 2020s, though 2024 data showed declines alongside the broader national trend.
Withdrawal symptoms include fatigue, pain, severe depression, and strong cravings.
Marijuana
In 2024, 64.2 million people aged 12 or older used marijuana in the past year, making it the most commonly used illicit drug in the United States, according to the 2024 NSDUH.7 Made from the dried leaves of the Cannabis sativa plant, marijuana produces a high due to the presence of tetrahydrocannabinol (THC).
Long-term use can cause mood swings, a lack of motivation, gastrointestinal problems, and depression.
Barbiturates
Barbiturates are prescription depressants used to treat conditions such as epilepsy. They relax the user, lower inhibitions, and aid sleep. The DEA warns that tolerance develops easily and overdose can be fatal.8
Withdrawal effects include nausea, cramps, seizures, vomiting, and hallucinations.
Sleeping Pills and Sedatives
Prescription sleep medications, including zolpidem (Ambien), eszopiclone (Lunesta), and zaleplon (Sonata), are sometimes called Z-drugs. They are intended for short-term use, but prolonged use can lead to tolerance, physical dependence, and escalating doses. Withdrawal from sleeping pills can cause rebound insomnia, anxiety, and in severe cases, seizures. Because withdrawal symptoms often mirror the condition the medication was prescribed to treat, many people find it hard to stop without medical support.
Hallucinogens
Hallucinogens can be natural, such as psilocybin mushrooms, or synthetic, such as LSD. They cause a distorted sense of reality and can make a person see or hear things that are not there. MDMA (ecstasy) acts as both a hallucinogen and a stimulant. In the 2024 NSDUH, 10.4 million people aged 12 or older reported past-year hallucinogen use, reflecting growing interest in substances like psilocybin, LSD, and MDMA.
Short-term effects include increased heart rate, high blood pressure, loss of appetite, and sleep disruption. Long-term use can cause paranoia and persistent visual disturbances.
Tobacco and Nicotine
Tobacco is one of the most addictive substances available. Despite advertising bans and warning labels in many countries, it remains widely used. Smoking is a leading cause of preventable death, contributing to stroke, heart disease, lung cancer, and cancers of the throat and mouth.
Behavioral Addictions
Addiction can also develop without a substance being involved. Compulsive behaviors like gambling and gaming activate the brain’s reward system in ways that parallel drug use, and the DSM-5 now recognizes gambling disorder as a diagnosable condition. People experiencing behavioral addictions may benefit from many of the same therapeutic approaches discussed here.
What Causes Drug Addiction?
No single factor causes addiction. Research from the National Institute on Drug Abuse shows that genetics, environment, trauma, and mental health each play a role, and they interact differently in every person. Two people can use the same substance and end up on very different paths.
- Genetics: NIH’s National Institute on Drug Abuse states that as much as half of a person’s risk of becoming addicted to nicotine, alcohol, or other drugs depends on their genetic makeup. If there is a family history of addiction, the chances of becoming addicted increase.
- Environment: The people, places, and things someone experiences daily greatly influence their thoughts, feelings, and behavior. For example, adolescents who have witnessed drug-taking at home are far more likely to take drugs themselves.
- Trauma: Any life events that have had a psychologically traumatic impact, especially as a child, can significantly increase the risk of drug abuse and addiction. Examples include sexual abuse, witnessing or experiencing violence, and being physically or emotionally neglected.
- Mental health: There is a link between mental illness and addiction in many cases. Around half of individuals with a substance use disorder will also experience a co-occurring mental disorder. There is no set pattern as to which comes first. Some people start to use substances to cope with the symptoms of their mental health condition. Whereas for others, mental health concerns such as anxiety and depression can be a side effect of taking drugs.
What Are the Four Stages of Drug Addiction?
Addiction develops gradually, even when it feels sudden to the person experiencing it. The path from first use to full dependence generally follows four stages, though the pace varies based on the substance and the individual.
Addiction typically moves through four recognizable stages: experimentation, regular use, harmful use, and full addiction. Each stage shifts the balance of control between the person and the substance. Recognizing where someone falls on this progression can help determine what level of care is most appropriate.
- Experimentation. A person tries a drug for the first time, whether at a social event, out of curiosity, under peer pressure, or to relieve pain, stress, or the symptoms of a mental health condition. The drug may be prescribed by a doctor or obtained illegally.
- Regular use. The person uses the drug with some regularity, often in social situations or in response to specific feelings. At this point, use is a pattern but not yet an addiction. The person still chooses when and how much to use.
- Harmful use. Drug use starts causing visible damage to the person’s life or to the people around them, yet the person continues. They may take increasing risks: associating with people involved in criminal activity, sharing needles, experimenting with higher doses, or trying new substances.
- Full addiction. Drugs consume the person’s daily life. The desire to use overtakes work, family, health, and safety. The person may have lost relationships, employment, or housing. There is little or no regard for consequences. The primary concern is relieving withdrawal symptoms and obtaining the next dose.
What Effect Does Addiction Have on the Brain?
Drugs change the brain’s reward system by flooding it with dopamine, the chemical responsible for feelings of pleasure. Over time, the brain adapts by producing less dopamine naturally and reducing the number of receptors that respond to it. A person with a substance use disorder may then need larger amounts of the drug to feel any effect, a process called tolerance, and may struggle to enjoy activities that once felt rewarding.
Substance use disorder affects many parts of the body, but the most significant impact is on the brain. A person can be both physically and psychologically dependent on a drug. Physical dependence means the body requires the substance to avoid withdrawal symptoms like nausea, tremors, and anxiety. Psychological dependence refers to the brain’s perception that it needs the drug, and the behavioral patterns that reinforce that belief.
With prolonged use, the brain’s natural ability to produce pleasure chemicals becomes impaired. If this happens, a person with a substance use disorder may no longer find satisfaction in people, activities, or situations that don’t involve drugs. These changes to brain chemistry are why addiction treatment often requires a combination of medical and behavioral approaches, and why willpower alone is rarely enough.
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How Is Drug Addiction Diagnosed?
A substance use disorder is a clinical diagnosis, not an informal label. Healthcare providers use the criteria in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5-TR) to determine whether a person’s drug use meets the threshold for a diagnosable condition. The assessment looks at 11 criteria, grouped into four categories.
The four DSM-5 categories and what they measure:
- Impaired control covers using more of a substance than intended, unsuccessful efforts to cut back, spending excessive time obtaining or recovering from the drug, and experiencing intense cravings.
- Social impairment includes failing to meet obligations at work, school, or home, continuing use despite relationship problems caused by it, and giving up important activities.
- Risky use means using the substance in physically dangerous situations or continuing despite knowing it is causing or worsening a physical or psychological problem.
- Pharmacological indicators refer to tolerance (needing more to achieve the same effect) and withdrawal (experiencing physical symptoms when use stops).
Meeting two or three criteria within a 12-month period indicates a mild substance use disorder. Four to five criteria suggest a moderate disorder, and six or more indicate a severe condition.
Only a qualified healthcare provider, such as a psychiatrist, psychologist, or licensed addiction counselor, can make a formal diagnosis. If you believe you or someone you know may have a substance use disorder, a professional evaluation is the most reliable next step.
What Are the Signs of Drug Addiction?
The warning signs of drug addiction span behavioral, physical, and social changes. They tend to accumulate over time rather than appear all at once.
The Surgeon General’s Report on Alcohol, Drugs and Health found that early intervention is the most effective way to help someone with a substance use problem who may be at risk for developing a full disorder.9
Recognizing these signs of addiction early can be the difference between a manageable problem and a crisis. The most common indicators, whether you notice them in yourself or in someone you care about, include:
- Sudden changes in personality, mood, or behavior. Increased agitation, irritability, or secrecy that was not present before.
- Withdrawal from friends and family. People with addiction often pull away from those not involved in their drug use, sometimes out of shame, guilt, or fear of judgment.
- Loss of interest in activities, responsibilities, or hobbies that used to matter. Cravings can become so consuming that everything else falls away.
- Declining performance at work or school. Side effects, withdrawal symptoms, and shifting priorities make it hard to follow a routine.
- Financial strain. Sustaining a drug habit is expensive. Borrowing money, selling possessions, or stealing are common.
- Visible physical changes. Rapid weight loss, skin problems, bloodshot eyes, changes in sleep patterns, and poor hygiene can all point to substance use.
If you see several of these patterns in someone close to you, it may be time to have a direct conversation. For guidance on how to approach that, see our page on how addiction affects families or our guide to staging an intervention.
Can Drug Addiction Be Prevented?
There is no guaranteed way to prevent drug addiction, but evidence-based strategies can reduce the risk, especially when applied early. The National Institute on Drug Abuse has found that prevention programs focused on families, schools, and communities can reduce initial substance use and delay the age of first exposure. Age of first use is one of the strongest predictors of whether a person will develop a substance use disorder later.
For parents and caregivers, direct conversations about the risks of drug use, started early and revisited over time, are among the most accessible prevention tools. Adolescents whose parents discuss substance use with them are less likely to start using than those who receive no guidance. School-based programs that build decision-making skills, stress management, and peer resistance have also shown measurable results in reducing experimentation.
For adults, knowing your own risk factors makes a difference. A family history of addiction, a co-occurring condition like anxiety or depression, chronic pain, and high-stress environments all increase vulnerability. Addressing these factors proactively through therapy, medical care, and healthy coping habits lowers the chance that substance use will escalate.
Safe prescribing practices also matter. CDC guidelines recommend that healthcare providers prescribe the lowest effective dose of opioids for the shortest necessary duration and explore non-opioid alternatives when possible. If you are prescribed pain medication, follow dosing instructions carefully, store the medication securely, and dispose of unused prescriptions through a community take-back program.
Prevention is not only about stopping first use. For people in recovery, ongoing participation in aftercare programs and support groups helps maintain the progress made in treatment and reduces the risk of relapse.
What to Do if You or Someone You Know Needs Help
If you recognize the signs described above in yourself or someone close to you, the most important thing is to take a step toward help. There are several practical options.
SAMHSA’s National Helpline is free, confidential, and available 24 hours a day, 365 days a year.10 It provides referrals to treatment services for substance use and mental health disorders in English and Spanish. Call 1-800-662-HELP (1-800-662-4357).
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A primary care doctor, therapist, or counselor can evaluate your situation and connect you to appropriate resources. Even if they cannot provide treatment directly, they will typically know who in your area can.
The Rehab.com treatment locator lets you search and compare local treatment centers by location, level of care, insurance, and specialty.
Treatment Options for Substance Use Disorder
Treatment for substance use disorder is available across the country and tailored to individual needs. Most plans combine medical and behavioral approaches. The process often begins with medically supervised detox to manage withdrawal, followed by a period of structured therapy, and then ongoing support to prevent relapse.
In 2024, of the 52.6 million Americans who needed substance use treatment, only about 1 in 5 received it. Cost, stigma, and uncertainty about where to start are the most commonly cited barriers. Federal law requires most insurance plans to cover substance use disorder treatment at parity with other medical care, and state-funded and low-cost programs are available in every state.
Detoxification
Detox is usually the first step. During medically supervised detox, healthcare professionals monitor withdrawal symptoms and provide medications to keep the process safe. Detox alone is not treatment. It stabilizes a person physically so they can engage in the therapeutic work that follows. The timeline varies by substance: alcohol and benzodiazepine withdrawal may require close medical observation due to seizure risk, while opioid withdrawal is intensely uncomfortable but rarely life-threatening when monitored.
Behavioral Therapies
Therapy is the core of most treatment plans. Cognitive behavioral therapy (CBT) helps people identify the thought patterns that drive substance use and develop healthier responses. Dialectical behavior therapy (DBT) builds emotional regulation and distress tolerance skills. Motivational interviewing strengthens a person’s commitment to change. These therapies are delivered in both individual and group settings, and often in combination.
Medication-Assisted Treatment (MAT)
For opioid and alcohol use disorders, FDA-approved medications can reduce cravings, ease withdrawal, and lower the risk of relapse. Opioid use disorder may be treated with methadone, buprenorphine (Suboxone), or naltrexone (Vivitrol). Alcohol use disorder may be treated with naltrexone, acamprosate, or disulfiram. MAT is most effective when paired with behavioral therapy: medication addresses the biological component while therapy works on the behavioral and psychological dimensions.
Levels of Care
Treatment intensity is matched to the severity of the disorder and each person’s circumstances. The American Society of Addiction Medicine (ASAM) defines a continuum of care ranging from early intervention to medically managed inpatient services. Common levels include outpatient counseling, intensive outpatient programs (IOP), partial hospitalization (PHP), and residential inpatient treatment. Many people step through multiple levels as they stabilize and progress. For a side-by-side comparison, see our levels of care guide.
Aftercare and Ongoing Support
Recovery does not end when a program concludes. Aftercare planning, which may include continued therapy, sober living arrangements, peer support groups, and regular check-ins with a provider, is essential to sustaining sobriety over time. Relapse is common and does not mean treatment has failed. Like any chronic health condition, a substance use disorder sometimes requires adjustments to the treatment plan along the way.
If you or someone you care about is struggling with drug addiction, the most effective thing you can do is take one concrete step today. Call a helpline, make an appointment, or use the facility locator below to compare programs near you. Recovery is possible, and it starts with asking for help.
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References
- American Society of Addiction Medicine. Definition of addiction. Accessed March 25, 2026. https://www.asam.org/quality-care/definition-of-addiction
- National Institute on Drug Abuse. Understanding drug use and addiction DrugFacts. Published June 2018. Accessed March 25, 2026. https://nida.nih.gov/publications/drugfacts/understanding-drug-use-addiction
- United Nations Office on Drugs and Crime. World Drug Report 2025. Published June 26, 2025. Accessed March 25, 2026. https://www.unodc.org/unodc/en/data-and-analysis/world-drug-report-2025.html
- Substance Abuse and Mental Health Services Administration. SAMHSA releases annual National Survey on Drug Use and Health. Published July 28, 2025. Accessed March 25, 2026. https://www.samhsa.gov/newsroom/press-announcements/20250728/samhsa-releases-annual-national-survey-on-drug-use-and-health
- National Center for Health Statistics. U.S. life expectancy hits record high as drug overdose deaths decline in 2024. Centers for Disease Control and Prevention. Published January 29, 2026. Accessed March 25, 2026. https://www.cdc.gov/nchs/pressroom/releases/20260129.html
- van Amsterdam J, Nutt D, Phillips L, van den Brink W. European rating of drug harms. J Psychopharmacol. 2015;29(6):655-660. doi:10.1177/0269881115581980
- Substance Abuse and Mental Health Services Administration. Key Substance Use and Mental Health Indicators in the United States: Results from the 2024 National Survey on Drug Use and Health. HHS Publication No. PEP25-07-007. Published 2025. Accessed March 25, 2026. https://www.samhsa.gov/data/sites/default/files/reports/rpt56287/2024-nsduh-annual-national/2024-nsduh-annual-national-html-071425-edited/2024-nsduh-annual-national.htm
- Drug Enforcement Administration. Barbiturates. Accessed March 25, 2026. https://www.dea.gov/factsheets/barbiturates
- Substance Abuse and Mental Health Services Administration; Office of the Surgeon General. Facing Addiction in America: The Surgeon General’s Report on Alcohol, Drugs, and Health. Washington, DC: US Department of Health and Human Services; 2016. https://www.ncbi.nlm.nih.gov/books/NBK424859/
- Substance Abuse and Mental Health Services Administration. SAMHSA’s National Helpline. Accessed March 25, 2026. https://www.samhsa.gov/find-help/national-helpline
- Narcotics Anonymous. Accessed March 25, 2026. https://na.org/
- Alcoholics Anonymous. Accessed March 25, 2026. https://www.aa.org/
