What medications are controlled substances?

October 10, 2025 •

4 min read

The U.S. Drug Enforcement Administration (DEA) places controlled substances into five schedules based on their potential for abuse and accepted medical use. Understanding what medications are controlled substances is crucial for patients and healthcare providers alike to ensure proper prescribing, handling, and use.

Quick Summary

Explains how the DEA classifies medications into five schedules based on abuse potential and medical use, covering common examples and the regulatory framework.

Key Points

DEA Classification: The U.S. government classifies controlled substances into five schedules (I-V) based on their abuse potential and medical use, with Schedule I having the highest risk and Schedule V the lowest.
High Abuse Potential: Schedule II drugs, like fentanyl and Adderall, have a high potential for abuse and severe dependence, despite having accepted medical uses.
Risks: All controlled substances carry a risk of physical and psychological dependence, tolerance, and addiction, even when used as prescribed.
Strict Regulation: Prescribing and dispensing controlled substances are tightly regulated by the DEA, requiring special licenses and strict tracking to prevent diversion and misuse.
No Refills for Schedule II: Prescriptions for Schedule II medications generally cannot be refilled; a new prescription is required for each fill.
Patient Responsibility: Patients must use controlled substances exactly as prescribed, be aware of potential risks, and inform their healthcare provider of any concerns or side effects.

The federal government, through the Controlled Substances Act (CSA), regulates the manufacture, possession, and use of certain medications due to their potential for abuse and addiction. These substances are categorized into five distinct schedules (I through V), with a drug's classification depending on its accepted medical use, abuse potential, and dependence liability. This system dictates the restrictions placed on prescribing, dispensing, and refilling these powerful medications.

The DEA's Five Drug Schedules

The DEA scheduling system provides a framework for regulating controlled substances. The schedules range from Schedule I, which has the highest potential for abuse and no accepted medical use, to Schedule V, which has the lowest abuse potential and a recognized medical purpose.

Schedule I

Substances in Schedule I have a high potential for abuse and no currently accepted medical use in the United States. Use of these drugs, even under medical supervision, is considered unsafe. These are not typically prescribed as medications and are illegal for recreational use at the federal level.

Examples: heroin, lysergic acid diethylamide (LSD), cannabis (marijuana), MDMA (ecstasy).

Schedule II

Schedule II drugs also have a high potential for abuse, with use potentially leading to severe psychological or physical dependence. However, they possess a currently accepted medical use in the United States, although often with severe restrictions. Prescriptions for Schedule II drugs are highly regulated; no refills are typically permitted without a new, separate prescription.

Examples: oxycodone (OxyContin), fentanyl, morphine, hydrocodone combination products (Vicodin), methamphetamine (Desoxyn), methylphenidate (Ritalin, Concerta), amphetamine (Adderall).

Schedule III

Substances in Schedule III have a lower potential for abuse than those in Schedules I or II. Abuse may lead to moderate or low physical dependence or high psychological dependence.

Examples: ketamine, anabolic steroids, testosterone, products containing less than 90 milligrams of codeine per dosage unit (Tylenol with codeine), buprenorphine.

Schedule IV

Drugs in Schedule IV have a low potential for abuse relative to Schedule III substances. They also have an accepted medical use and a low risk of dependence.

Examples: alprazolam (Xanax), clonazepam (Klonopin), diazepam (Valium), lorazepam (Ativan), zolpidem (Ambien), tramadol.

Schedule V

Schedule V drugs have the lowest potential for abuse among controlled substances. They generally consist of preparations containing limited quantities of certain narcotics and are often used for antitussive, antidiarrheal, and analgesic purposes.

Examples: cough preparations containing less than 200 milligrams of codeine per 100 mL (e.g., Robitussin AC), pregabalin (Lyrica), diphenoxylate/atropine (Lomotil).

Comparing the DEA Controlled Substance Schedules


Feature	Schedule I	Schedule II	Schedule III	Schedule IV	Schedule V
Medical Use	No currently accepted medical use	Accepted medical use with severe restrictions	Accepted medical use	Accepted medical use	Accepted medical use
Abuse Potential	High	High	Moderate to low	Low	Lowest
Dependence Risk	Severe psychological and physical dependence	Severe psychological and physical dependence	Moderate physical or high psychological dependence	Limited physical or psychological dependence	Limited physical or psychological dependence
Refills	Not applicable	No refills without new prescription	Up to 5 refills within 6 months	Up to 5 refills within 6 months	May be refilled as authorized
Examples	Heroin, LSD	Fentanyl, Oxycodone	Ketamine, Anabolic Steroids	Xanax, Ambien	Robitussin AC, Lyrica

Pharmacology and Risks of Controlled Substances

Pharmacologically, controlled substances affect the central nervous system to produce their therapeutic and recreational effects. Opioids, for instance, bind to mu-opioid receptors to reduce pain signals, while stimulants increase alertness and energy. The potential for addiction arises from these effects, as patients may develop a psychological dependency or tolerance, requiring higher doses to achieve the same effect.

Potential Risks and Side Effects

Dependence and Addiction: Long-term use can lead to physical dependence, where the body adapts to the drug and requires it to function normally. Addiction involves a psychological compulsion to seek and use the drug despite negative consequences.
Withdrawal Symptoms: Abruptly stopping or reducing a controlled substance can trigger a range of withdrawal symptoms, from tremors and anxiety to severe pain and convulsions, depending on the drug.
Tolerance: Over time, the body may become tolerant, meaning a higher dose is needed to achieve the same effect. This can increase the risk of overdose.
Severe Side Effects: These can include respiratory depression (especially with opioids and depressants), cardiovascular complications, cognitive impairment, and mood disturbances.
Overdose: Misuse or taking an excessively high dose can lead to overdose, which can be fatal, particularly when controlled substances are mixed with other drugs or alcohol.

Responsible Prescribing and Patient Management

Healthcare providers who prescribe controlled substances must hold a DEA registration and adhere to strict regulations. They must ensure the prescription is for a legitimate medical purpose and consider the patient's risk of misuse or addiction. Patient education on risks, proper use, and safe storage is a critical part of the process. Tools like Prescription Drug Monitoring Programs (PDMPs) help clinicians track a patient's controlled substance history to identify potential misuse, such as doctor shopping.

Conclusion

Understanding what medications are controlled substances and the specific schedule they belong to is essential for both patients and medical professionals. The DEA's scheduling system, based on abuse potential and medical utility, serves as a crucial regulatory tool to balance therapeutic access with the prevention of misuse and addiction. Patients taking controlled substances should always follow their doctor's instructions carefully, be aware of the risks, and never share or sell their medication. Through informed usage and vigilant healthcare practices, the benefits of these necessary medications can be maximized while their significant risks are minimized.

For more information on the DEA's drug scheduling system, visit the DEA's official website.

Frequently Asked Questions

Controlled substances are classified by the DEA into five schedules (I-V) based on their accepted medical use, abuse potential, and potential for causing psychological or physical dependence.

Schedule I substances have a high potential for abuse and no accepted medical use, such as heroin. Schedule II substances also have a high abuse potential and risk of severe dependence, but they do have an accepted medical use, like oxycodone and fentanyl.

No, most prescription medications are not controlled substances. Common medications for conditions like high blood pressure, diabetes, and infections are not scheduled because they do not have a significant risk of abuse or dependence.

Examples of Schedule IV medications include anti-anxiety drugs like Xanax (alprazolam) and Valium (diazepam), and sleeping pills like Ambien (zolpidem), which have a low potential for abuse and dependence.

Refill rules differ based on the drug's schedule. Higher-schedule drugs like Schedule II medications have the tightest restrictions, with no refills permitted, while lower-schedule drugs (III, IV, V) have more lenient refill policies to reflect their lower abuse potential.

Yes, it is possible to develop a physical or psychological dependence on controlled substances even when following a doctor's orders. This can happen over a long period of use and is distinct from intentional abuse.

To prevent misuse and diversion, you should dispose of unused controlled substances properly. Many pharmacies and local law enforcement agencies have drug take-back programs. The DEA also sponsors National Prescription Drug Take-Back Days.