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Drug Classifications

There are thousands of different drugs, both legal and illegal. Because of this variety it is often necessary to classify drugs into several types for legal, medical, and treatment purposes. There are several ways to classify drugs, including by chemical similarities, effects on the mind and body, and legal definitions.

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What Are Drug Classifications?

Drug classifications are a way to organize drugs into categories. There are many reasons to do this.

Classifying drugs by chemical similarities is useful because drugs that are chemically similar often have similar impacts and risks. An individual who is addicted to a given drug is more likely to abuse a chemically similar drug. Also, the same treatment is often effective for chemically similar drugs. Despite these generalities, chemically similar drugs may have very different legal and medical impacts.

Many people classify drugs by how they impact the mind and body. Some drugs have a tendency to make a user active and energetic, while others make an individual feel relaxed and calm. These types of substances might be described as “uppers” and “downers,” respectively.

Most countries have a legal classification system for drugs. These systems determine the circumstances, if any, under which that drug is legal, various requirements for that drug, and any legal penalties associated with possession, distribution, or manufacture of it. Legal classifications are generally based on the perceived medical value of a drug along with its perceived risk and danger.

There is considerable disagreement about how drugs should be classified, even among experts. This means that the same drug may be classified differently under 2 schemes, or that 2 systems may use categories with the same name. Due to these disagreements it’s impossible to create a “definitive” set of drug classifications. However, some of the most common are listed below.

Drug Classifications Based On Chemical Makeup


Alcohol is the most widely abused substance across most of the world, including in the United States. Legal to some extent in all 50 states, alcohol impacts numerous body systems and causes a host of effects in the user. Alcohol creates feelings of euphoria and lowers inhibitions, but it also severely impairs judgment, perception, and reaction times. Alcohol is a Central Nervous System (CNS) Depressant, but it causes the most severe long-term damage to the liver. There are many forms of alcohol, including:

  • Beer
  • Wine
  • Liquor


Also called Opiates, Opioids are either derived from the drug Opium or from chemicals designed to mimic it. Opioids work by acting on receptors in the brain, sometimes by mimicking the effects of neurotransmitters. This can enable Opioids to serve as powerful Painkillers, but also can cause feelings of intense pleasure and lead to addiction. Opioid addiction is one of the most serious problems faced by America today. Opioids are some of the most addictive of all known substances, and they are also some of the deadliest. Some of the most well-known Opioids include:

  • Heroin
  • Fentanyl
  • Oxycodone


Benzodiazepines, or Benzos, are a class of drugs that function by interacting with the neurotransmitter gamma-aminobutyric acid-A (GABA-A). Each Benzo interacts with GABA-A differently, which is why each Benzo impacts the body and mind differently. Benzos are prescribed to treat a wide variety of psychiatric and sleep conditions, but they are very commonly abused. Benzos are highly addictive and can cause numerous medical and psychiatric problems when not used as intended. Examples of Benzos include:

  • Ativan
  • Valium
  • Xanax


Cannabinoids are a class of drugs that are chemically similar to Tetrahydrocannabinol (THC), the active agent in Marijuana. Cannabinoids create feelings of elation, known as a high, but they also negatively impact mental and physical functioning. Cannabinoids are the most widely abused drugs after alcohol, and they are increasingly gaining legal acceptance. Although considered less addictive than other drug classifications, Cannabinoids can seriously damage a person’s mental and physical health. Examples of Cannabinoids include:

  • Marijuana
  • Hashish


Barbiturates act on the central nervous system by slowing down its functioning. Barbiturates are derivatives of the chemical barbituric acid. Barbiturates were historically popular for the treatment of psychiatric and sleep disorders, and they are still used for anesthesia and treatment of conditions like epilepsy and headaches. Barbiturates are highly addictive, and they also present a very high overdose risk as they cause many body systems to shut down. Examples of Barbiturates include:

  • Amytal
  • Luminal
  • Phenobarbital

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Drug Classifications Based On Effect


More commonly referred to as “downers,” Depressants create feelings of relaxation and tiredness. While many serve legitimate purposes in the fight against mental illness and sleep deprivation, they are very commonly abused because they may also create feelings of euphoria. Depressants are not only some of the most highly addictive drugs, but they are also some of the most highly dangerous and likely to cause overdose. Examples of Depressants include:

  • Alcohol
  • Opiates
  • Barbiturates


Also known as “uppers,” the primary use of Stimulants is to increase energy, concentration, and wakefulness. Stimulants are said to provide a “rush.” In the short term, Stimulants are believed to increase productivity and performance while producing an excited high of pleasure. In the long term, Stimulants are incredibly addictive and have a very high potential for abuse. Examples of Stimulants include:

  • Adderall
  • Cocaine
  • Meth


Hallucinogens alter the user’s perception of reality. Often this results in auditory and visual hallucinations, a process known as “tripping.” Although Hallucinogens are generally less addictive than other drug classifications, their immediate impacts are generally more severe and dangerous. Examples of Hallucinogens include:

  • LSD
  • Psilocybin Mushrooms
  • PCP


Inhalants are a vast range of chemicals that are ingested primarily by breathing them in, or huffing. Most inhalants are commonly used materials that are in no way designed to be ingested by humans. While there is incredible variety between inhalants, most produce feelings of a high. Inhalants are less studied than most other drugs. While they tend to be less addictive than many other substances, the use of Inhalants is incredibly dangerous and causes many serious health effects. Examples of commonly abused Inhalants include:

  • Paint thinner
  • Nail polish remover
  • Gasoline
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Drug Classifications Based On Legal Definitions

The Federal Government passed the Controlled Substances Act in 1970 in response to the drug epidemic. This act established 5 drug classifications or schedules. What schedule a drug is placed in is determined by its legitimacy and the value of its potential medical uses, along with its potential for abuse and risk of addiction. The exception to this is international treaties. The United States must classify certain drugs in certain schedules to comply with certain diplomatic agreements, such as the Single Convention on Narcotic Drugs.

Schedule V

Schedule V drugs have the fewest regulations and lowest penalties of any federal drug classification. Schedule V drugs have a legitimate accepted medical purpose, have a lower potential for abuse than Schedule IV drugs, and have a lower potential for addiction than Schedule IV drugs. Examples include:

  • Lomotil
  • Motofen
  • Lyrica

Schedule IV

Schedule IV drugs have regulations and penalties in between those of Schedule V and Schedule III drugs. Schedule IV drugs have a legitimate accepted medical purpose, have a low potential for abuse, and have a low potential for addiction. Examples include:

Schedule III

Schedule III drugs have more regulations and harsher penalties than Schedule IV drugs and fewer regulations and less severe penalties than Schedule II drugs. Schedule III drugs have a legitimate acceptable medical purpose, have a lower abuse potential than Schedule I and II drugs, and have a moderate or low potential for addiction. Examples of Schedule III drugs include:

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Schedule II

Schedule II drugs have more regulations and harsher penalties than any drug classification other than Schedule I drugs. Schedule II drugs have a legitimate accepted medical use, a high potential for abuse, and a severe dependence risk. Examples of Schedule II drugs include:

Schedule I

Schedule I drugs have the most regulations and harshest penalties of any drugs. Schedule I drugs have no legitimate accepted medical use and a high potential for abuse. Examples of Schedule I drugs include:

  • Ecstasy
  • Quaaludes
  • GHB
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Don’t Let Any Drug Ruin Your Life

It doesn’t matter whether you or a loved one are addicted to a Schedule V Benzodiazepine or a Schedule I Opioid. Addiction is a terrible condition, and it holds you back from leading the life you deserve to live. While all drug classifications will require specialized treatment, there is a rehab center out there that can help. Contact a treatment provider now.