Drugs, chemicals, and substances used in drug production are categorised into five distinct schedules based on their accepted medical use and potential for abuse or dependency.
A drug’s abuse potential plays a key role in its classification. Schedule I drugs, for instance, carry the highest risk of abuse and severe dependence.
As the schedule progresses (Schedule II, III, etc.), the risk decreases, with Schedule V having the lowest abuse potential.
The Controlled Substances Act (CSA) provides a detailed list of scheduled drugs, though it primarily includes base chemicals rather than their various salts, isomers, or derivatives, which may also be classified as controlled substances.
These lists serve as general references rather than exhaustive compilations.
It’s important to note that a substance doesn’t have to be officially listed to be treated as a Schedule I drug in criminal cases.
A controlled substance analogue—designed for human consumption and chemically or pharmacologically similar to a Schedule I or II drug—can also be subject to regulation, even if it is not an approved medication in the U.S.
(Refer to 21 U.S.C. §802(32)(A) for definitions and 21 U.S.C. §813 for scheduling details.)
Schedule I
Schedule I drugs, substances or chemicals are defined as drugs with no currently accepted medical use and a high potential for abuse.
Some examples of Schedule I drugs are:
- Heroin
- Lysergic acid diethylamide (LSD)
- Marijuana (cannabis)
- 3,4-methylenedioxymethamphetamine (ecstasy)
- Methaqualone
- Peyote
Schedule II
Schedule II drugs, substances, or chemicals are defined as drugs with a high potential for abuse, with use potentially leading to severe psychological or physical dependence.
These drugs are also considered dangerous. Some examples of Schedule II drugs are:
- Combination products with less than 15 milligrams of hydrocodone per dosage unit (Vicodin)
- Cocaine
- Methamphetamine
- Methadone
- Hydromorphone (Dilaudid)
- Meperidine (Demerol)
- Oxycodone (OxyContin)
- Fentanyl
- Dexedrine
- Adderall
- Ritalin
Schedule III
Schedule III drugs, substances, or chemicals are defined as drugs with a moderate to low potential for physical and psychological dependence.
Schedule III drugs abuse potential is less than Schedule I and Schedule II drugs but more than Schedule IV.
Some examples of Schedule III drugs are:
- Products containing less than 90 milligrams of codeine per dosage unit (Tylenol with codeine)
- Ketamine
- Anabolic steroids
- Testosterone
Schedule IV
Schedule IV drugs, substances, or chemicals are defined as drugs with a low potential for abuse and low risk of dependence.
Some examples of Schedule IV drugs are:
- Xanax
- Soma
- Darvon
- Darvocet
- Valium
- Ativan
- Talwin
- Ambien
- Tramadol
Schedule V
Schedule V drugs, substances, or chemicals are defined as drugs with lower potential for abuse than Schedule IV and consist of preparations containing limited quantities of certain narcotics.
Schedule V drugs are generally used for antidiarrheal, antitussive, and analgesic purposes.
Some examples of Schedule V drugs are:
- Cough preparations with less than 200 milligrams of codeine or per 100 millilitres (Robitussin AC)
- Lomotil
- Motofen
- Lyrica
- Parepectolin