Addiction Drug Use What Is a Controlled Substance? By Elizabeth Hartney, BSc, MSc, MA, PhD Elizabeth Hartney, BSc, MSc, MA, PhD Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada. Learn about our editorial process Updated on January 27, 2022 Medically reviewed Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by John C. Umhau, MD, MPH, CPE Medically reviewed by John C. Umhau, MD, MPH, CPE John C. Umhau, MD, MPH, CPE is board-certified in addiction medicine and preventative medicine. He is the medical director at Alcohol Recovery Medicine. For over 20 years Dr. Umhau was a senior clinical investigator at the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health (NIH). Learn about our Medical Review Board Print Moussa81 / Getty Images Table of Contents View All Table of Contents Schedule 1 Drugs Schedule 2 Drugs Schedule 3 Drugs Schedule 4 Drugs Schedule 5 Drugs Prescribed Controlled Substances Frequently Asked Questions Controlled substances are illegal or prescription drugs regulated by the Controlled Substances Act (CSA) in the United States. Recognizing the potential that certain medications have for misuse and dependence, Congress enacted the CSA as part of the Comprehensive Drug Abuse Prevention and Control Act of 1970. This act categorizes all substances that are regulated under federal law into “schedules,” depending on how potentially dangerous they are. The schedule the drug is placed under depends on its medical use, its potential for abuse, and its safety or how easily people become dependent on it. Careful consideration has gone into this categorization. The control of drugs through law exists to protect people from the harm that these drugs can do. It is based on research from many different sources into the potential harmfulness of the drug, both to individuals and to society. The five schedules of drugs should not be confused with the five classes of drugs, a different way of organizing drugs according to their main properties. The five classes of drugs are narcotics, depressants, stimulants, hallucinogens, and anabolic steroids. This article discusses each of the five schedules of controlled substances and the different substances found under each classification. It also covers what you need to know if your doctor prescribes a controlled substance. Common Drug Laws and Terms Schedule 1 Drugs Schedule I drugs (the law uses Roman numerals one through five) have a high potential for abuse. They currently have no federally accepted medical use in treatment in the U.S., and there is a lack of accepted safety for use of the drug or substance under medical supervision. Examples of Schedule I substances include: Gamma-hydroxybutyric acid (GHB) Heroin Lysergic acid diethylamide (LSD) Methaqualone Marijuana is the only Schedule I drug that is legal for medicinal and recreational uses in many states. However, many experts believe the drug's status should be changed to allow for more comprehensive studies to determine the medical benefits of marijuana. Schedule 2 Drugs Schedule II drugs and substances also have a high potential for abuse. They differ from Schedule I drugs in that they do have a currently accepted medical use in treatment in the U.S. or a currently accepted medical use with severe restrictions. Examples of Schedule II substances include: Cocaine Methadone Methamphetamine Morphine Phencyclidine (PCP) Abuse of schedule II drugs may lead to severe psychological or physical dependence. Schedule 3 Drugs Schedule III drugs and substances have less potential for abuse than the drugs or substances in Schedules I and II. They have a currently accepted medical use in treatment in the U.S. Abuse of the drug or substance may lead to moderate or low physical dependence or high psychological dependence. Examples of Schedule III substances include: Anabolic steroids Barbiturates Codeine Hydrocodone with aspirin or Tylenol Schedule 4 Drugs These drugs and substances have a low potential for abuse relative to those in Schedule III. The drug or substance has a currently accepted medical use in treatment in the United States. Abuse of the drug or other substance may lead to limited physical dependence or psychological dependence relative to the drugs or other substances in Schedule III. Examples of Schedule IV substances include: Darvon Equanil Talwin Valium Xanax Schedule 5 Drugs The drug or substance has a low potential for abuse relative to those in Schedule IV. The drug or other substance has a currently accepted medical use in treatment in the United States. Abuse of the drug or other substances may lead to limited physical dependence or psychological dependence relative to the drugs or other substances in Schedule IV. Schedule V drugs include cough medicines with codeine. Recap Controlled substances are classified into schedules based on their medical value and potential for abuse. Schedule 1 drugs have no federally recognized medical purpose and high risk for dependence and abuse. Schedule 2 drugs may have some purpose in restricted medical settings. Schedules 3 have a lower risk for dependence and may be prescribed for medical treatment. Schedule 4 and 5 drugs have a lower potential for abuse. If Your Doctor Prescribes a Controlled Substance While not all prescription drugs are controlled, there are several (for example, opioid pain medications) that do fall under the category of controlled substances. If your doctor prescribes one of these drugs, it's essential that you only take it as directed. In addition to having limited refills, you may need to sign a pain medication agreement, or a contract between you and the doctor to ensure that you're taking the drugs exactly as prescribed. While the details can vary from doctor to doctor, the contract may also ask you to agree to: Get your prescription from only one pharmacyNot request or take pain medications from another providerSubmit to random drug testing 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. A Word From Verywell There are times that your doctor may prescribe a controlled substance to treat a health condition. You should always discuss proper dosage and administration with your doctor. Carefully following the instructions can help minimize the risks of taking a controlled substance for the treatment of a health condition. Frequently Asked Questions What is a controlled substance? A controlled substance is any drug or chemical that has its possession, use, or manufacture regulated by the government. These substances are regulated due to their potential for misuse, abuse, or addiction. What’s the difference between schedules of drugs and classes of drugs? Schedules of drugs refer to how a drug is regulated by the U.S. government. Classes of drugs refer to the main properties of a substance and how it affects the body. Which schedule of drugs require a prescription? Schedule 3, Schedule 4, and Schedule 5 drugs are available for use with a prescription. Schedule 2 drugs may be used in medical settings with extreme restrictions. Schedule 1 drugs, however, do not have any accepted medical use and cannot be acquired with a prescription. 3 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. Gabay M. The federal Controlled Substances Act: Schedules and pharmacy registration. Hosp Pharm. 2013;48(6):473-474. doi:10.1310/hpj4806-473 Corroon J, Kight R. Regulatory status of cannabidiol in the United States: A perspective. Cannabis Cannabinoid Res. 2018;3(1):190-194. doi:10.1089/can.2018.0030 U.S. Drug Enforcement Administration. The Controlled Substances Act. Additional Reading U.S. Drug Enforcement Administration. Drugs of abuse; A DEA resource guide. By Elizabeth Hartney, BSc, MSc, MA, PhD Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit Get Treatment for Addiction Advertiser Disclosure × The offers that appear in this table are from partnerships from which Verywell Mind receives compensation.