Scheduling and Drug Classification Charts: Making Sense of Drugs

Last Updated on January 25, 2023

variety of drugs

Drug classification and scheduling systems are helpful ways for people of all backgrounds and professions to clearly distinguish the potential dangers of various drugs and prescription medications. But for those who don’t understand the classification system, it may just seem like a bunch of legal jargon and nonsense.

Anyone can access an extensive drug classifications chart on the Drug Enforcement Agency’s (DEA) website or read about the various chemical classifications of drugs online, but it won’t mean much if you don’t understand the purpose of the classifications or how they work.

In this blog, we’ll provide some context on drug scheduling and chemical classifications, how they came about, and why they’re helpful, as well as a few drug classifications charts featuring some of the most commonly abused drugs in the U.S. This information can be very helpful for anyone who is taking a new medication, has a loved one who is addicted, or is addicted to drugs themselves.

What is Drug Scheduling?

In the United States, drugs and certain chemicals that are used to make drugs are organized into five different categories (or schedules) based on their potential for abuse, safety, addictive potential, and whether it has any legitimate medical uses.1

The DEA uses drug schedules as a way to classify and organize substances so law enforcement agents, lawmakers, and medical experts know how to handle them. Drug scheduling also makes the prescription drug industry safer, as it indicates the dependency potential and degree of risk involved with taking a certain prescription drug.

Drugs weren’t always classified and organized by schedule though. It wasn’t until the 1970s when the Controlled Substances Act (CSA) was signed into law that the DEA and FDA were given the power to determine which substances were fit for medical use and which were not.2 Since then, some of the drugs listed in the CSA have been added, deleted, or changed to a different schedule.

A full and comprehensive drug classifications chart is available per the DEA in part 1308 of the Title 21 Code of Federal Regulations,3 but the chart below is a list of some of the most commonly abused substances and their current scheduling.

SchedulingDescriptionExamples of Commonly Abused Substances
Schedule I DrugsThese drugs have no medical use and a high potential for abuse.
Schedule II DrugsThese drugs have a high potential for abuse and can potentially lead to severe psychological or physical dependence. Although the risk of addiction and dependence is high, these drugs do have accepted medical uses. Users can only legally obtain them with a prescription.
Schedule III DrugsThese drugs have a moderate to low potential for physical and psychological dependence, but they can still be dangerous when misused.
Schedule IV DrugsThese drugs have a low potential for abuse and a low risk of dependence, in comparison to Schedule III drugs. Although they have clear medical uses, when they are misused or abused with other drugs or alcohol, they can present a high risk for physical or psychological danger.


Schedule V Drugs

These drugs have a lower potential for abuse than Schedule IV drugs and a low risk of dependence.
  • Robitussin AC
  • Lomotil
  • Motofen
  • Lyrica
  • Parepectolin

Sources: https://www.dea.gov/drug-scheduling; https://www.deadiversion.usdoj.gov/schedules/orangebook/c_cs_alpha.pdf

Although it is rare for controlled substances to be reclassified, some individuals oppose marijuana’s status as a Schedule I drug due to scientific evidence and studies that show medical marijuana has medicinal value. As of now (2019), marijuana is still classified as a Schedule I drug under federal law, but many states have legalized some form of marijuana.4

What are the Chemical Classifications of Drugs?

Drugs may also be classified into chemical types based on the physical and psychological effects they cause. Similar to scheduling (the legal classification system for drugs), organizing illegal drugs, prescription drugs, and other illegal substances in this way makes it easier for people of all professions and walks of life to understand the potential risks and benefits of drug usage.

Chemical Drug Classifications Chart

Chemical ClassificationDescriptionExamples of Commonly Abused Substances
CannabisThese drugs are made from the hemp plant and contain THC, which is a mind-altering chemical.
  • Bhang
  • Hashish
  • Hashish oil
DepressantsThese drugs slow down brain activity and provide a calming and sedating effect. Prescription medications in this class are particularly useful for treating anxiety and sleep disorders.
HallucinogensThese drugs severely distort the user’s sense of reality by affecting the central nervous system.
InhalantsMany inhalants are household products. These substances are most often abused by teenagers.
  • Paint/paint thinners
  • Glue
  • Gasoline
  • Markers
  • Pen ink
New Psychoactive Substances (NPS)These drugs may also be referred to as “legal highs,” “bath salts,” or “research chemicals” and are designed to evade the law.
OpioidsThese drugs are frequently prescribed by doctors to treat cough and pain. They work by binding to opioid receptors in the brain, spinal cord, and other areas of the body to relieve pain and provide an overall calming effect.
StimulantsThese drugs affect the central nervous system and increase alertness, attention, energy, blood pressure, heart rate, and breathing rate.

Sources: https://www.drugabuse.gov/drugs-abuse/commonly-abused-drugs-charts; https://www.unodc.org/LSS/Page/NPS

Learn More About Addictive Substances

If you’re interested in learning more about addictive substances and commonly abused prescription drugs, illegal drugs, and herbal supplements, visit our Drug Glossary for in-depth resources and information on various types of addictive drugs.


  1. https://www.dea.gov/drug-scheduling
  2. https://www.dea.gov/controlled-substances-act
  3. https://disa.com/map-of-marijuana-legality-by-state
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