Drug Classifications: Grouping Psychoactive Substances into Categories

An Overview of Drug Classifications

There are thousands of drugs (psychoactive substances) that are used by people all over the world. Although all are different, many share similarities For this reason, drug classifications are used to simplify and generalize.

Drugs are classified in many different ways. 

The medical community and pharmaceutical industry professionals normally classify drugs according to their chemical type or the physiological changes they induce in the human body. The psychiatric and rehab communities typically classifies drugs in this manner as well. However, chemical type and physiological effects are not the only ways to classify drugs.

Other organizations may all have their own reasons for grouping certain drugs together. Law enforcers tend to classify drugs under their legal status or dependency potential. Lay people and drug users are more likely to classify them depending on the type of “high” they create as well as the environment or ways in which they’re used.

The classifications below are some common drug classifications. Some drugs may appear in multiple categories, because there are many ways to classify drugs. The associated risks outlined for each category may not necessarily apply to all users.

Drug Classifications Based on Chemical Similarity

Cannabinoids: Marijuana and Other Cannabis-Containing Substances

Better known as Marijuana, plants from the family Cannabaceae, including Cannabis sativa, Cannabis indica, and Cannabis ruderalis can be used directly or processed into products that can induce a high. 

Cannabis products are usually smoked, ingested, or vaporized and inhaled, which allows cannabinoids to bind with receptors in the brain for a “high,” among many other physiological effects.

While the entirety of a cannabis plant contains at least trace amounts of cannabinoids, the leaves are and flowers are especially potent. The resin can be processed into hashish, which is quite a powerful preparation.

Examples and Street Names of Drugs Classified as Cannabinoids:

  • Marijuana (Dope, reefer, pot, joint, bud, sinsemilla, weed, skunk, trees, ganja, boom, hash, hemp, and Mary Jane)

Associated Risks with the Cannabinoid Drug Classification: 

  • Panic attacks
  • Depression
  • Psychosis
  • Damage in juvenile or children’s brains
  • Slowed response
  • Lack of coordination
  • Respiratory infections
  • Hallucinations
  • Loss of coordination and balance
  • Increased risks when driving or operating heavy machinery
  • Memory loss
  • Psychological addiction.

Synthetic Cannabinoids and Synthetic Cathinones

Synthetic Cannabinoids are chemically identical to the active ingredients in cannabis and “khat” or Catha edulis. As such, these drugs also have identical effects as their naturally derived counterparts, namely euphoria and stimulation. 

However, these compounds are often used in extremely high doses to achieve a high that would be difficult to achieve through just smoking, ingesting, or vaping the natural plant products.

Examples and Street Names of Drugs Classified Synthetic Marijuana and Synthetic Cathinones:

  • Synthetic Cathinones (Bath salts)
  • Synthetic Weed (PABS, Monkey dust, Plant food, fake weed, K2, Yucatan fire, skunk, genie, moon rocks, herbal smoking blends, Bombay blue, and bliss)

Associated Risks with the Synthetic Marijuana and Synthetic Cathinone Drug Classification:

  • Paranoia
  • Seizures
  • Hallucinations
  • Hypertension
  • Agitation
  • Headaches
  • Kidney failure
  • Slowed neurological functions.

Opiates and Opioids

Opiates are drugs that are derived from the Papaver somniferum plant, otherwise known as the opium poppy. Opioids are either created synthetically to mimic opiates or are partially synthesized and partially derived from the opium poppy.

Both opiates and opioids are generally classified as depressants and narcotics and have been used since ancient times for their painkilling effects as well as for recreational purposes.

Opioids are widely used in modern medicine for a wide range of applications, particularly in pain control. The use and availability of some opioids, such as heroin and morphine, are strictly controlled due to their extremely high potential for physical and psychological addiction.

Examples and Street Names of Drugs Classified as Opioids and Opiates:

  • Morphine
  • Codeine
  • Methadone
  • Laudanum
  • Percocet
  • Oxycodone
  • Hydrocodone
  • Fentanyl
  • Carfentanil
  • Grey Death
  • Prescription painkillers
  • Heroin (dope, junk, brown sugar, smack, horse, China white, cheese, skag)

Associated Risks with the Opioid and Opiate Drug Classification:

  • Heavy sedation
  • Hepatitis and HIV risks if injected using contaminated paraphernalia
  • Impaired coordination
  • Impaired judgment
  • Confusion
  • Fatal overdose
  • Severe withdrawal


Benzodiazepines, more commonly referred to as Benzos,  are a widely-prescribed class of drugs used for treating insomnia, anxiety, and alcohol dependence among many other conditions. 

While there are dozens of different types of benzodiazepines, they mostly work by triggering a release of tranquilizing chemicals in the brain. They are broadly classified as depressants or sedatives.

Combining benzodiazepines with another depressant drug such as alcohol can lead to serious complications. As with opioids, these drugs are commonly prescribed, which can raise their potential for abuse. They are also often bought off the black market for recreational purposes.

Examples and Street Names of Drugs Classified as Benzodiazepines:

Associated Risks with the Benzodiazepine Drug Classification:

  • Heavy sedation
  • Confusion
  • Blackouts
  • Depression
  • Respiratory distress
  • Memory loss
  • Sexual dysfunction
  • Lethal overdose

Drug Classifications Based on Effects on the Mind and Body

Depressants or Downers

Depressants are drugs that reduce the brain’s neurotransmission levels or reduce the ability of the body to be stimulated. They are often contrasted with stimulants (uppers) that have a broadly opposite effect. 

Downers are among the most widely abused types of drugs available, with both legal and illegal varieties of downers being among the most commonly abused drugs in the world today.

Examples and Street Names of Drugs Classified as Depressants or Downers:

  • Benzodiazepines
  • Opioids and opiates
  • Alcohol
  • Cannabis (in small amounts)
  • Barbiturates
  • Muscle relaxants
  • Antihistamines
  • Alpha and beta-blockers
  • Hypnotics
  • Antipsychotics
  • Anticholinergics.

Associated Risks with the Depressant or Downer Drug Classification:

  • Disassociation
  • Delayed response to stimuli
  • Memory loss
  • Fatigue
  • Slurred speech
  • Confusion
  • Poor concentration
  • Lowered blood pressure
  • Slowed breathing
  • Constipation
  • Addiction
  • Depression
  • Weight gain
  • Weakness
  • Fever
  • Delirium
  • Hallucinations

Stimulants or Uppers

Stimulants are types of drugs that increase activity in the central nervous system. They are commonly described as having “invigorating” effects. 

Users will typically feel more alert and may report improved endurance. Some users will also have a diminished appetite for food and sleep.

Examples and Street Names of Drugs Classified as Stimulants or Uppers:

  • Cocaine
  • Methamphetamines (Crank, speed, kibbles, and bits)
  • MDMA
  • Ephedrine
  • Caffeine
  • Nicotine
  • Ritalin
  • Pseudoephedrine
  • Khat
  • Cannabis (in some users)
  • Bath salts

Associated Risks with the Stimulant or Upper Drug Classification:

  • Elevated blood pressure
  • Increased risk of stroke
  • After-use “crashes”
  • Addiction
  • Lowered sensitivity to stimulation
  • Brain damage
  • Paranoia
  • Anxiety
  • Grinding of teeth
  • Psychosis

Dissociative Drugs

These types of drugs can affect the parts of the brain responsible for cognition, including memory and learning. They also typically change the way the brain uses dopamine, a chemical central to the brain’s reward system.

Dissociative drugs can create a feeling of being detached from reality, hence the name for this category of drugs. The effects are typically less predictable than most other commonly-abused drugs.

Examples and Street Names of Drugs Classified as Dissociative Drugs:

  • Ketamine (Special K)
  • Dextromethorphan (DXM)
  • Phenylcyclohexyl piperidine (PCP, angel dust, superweed, embalming fluid, hog)
  • Salvia (magic mint, pastora, sally-D, diviner’s sage)

Associated Risks with the Dissociate Drug Classification:

  • Distorted perception of time and space
  • Detachment from reality
  • Memory impairment
  • Learning difficulty
  • Short attention span
  • Hallucinations
  • Delirium
  • Fever
  • Intense psychological cravings


This loose category of diverse drugs can change a user’s perception of their surroundings. In many cases, they can also alter one’s thoughts and strongly influence certain emotional responses. 

The use of hallucinogens is often associated with religious experiences. So-called classic hallucinogens are most often derived from plant or fungal extracts.

Dissociative drugs are often classed as hallucinogens, but the “classic hallucinogens” included in this category do not typically cause the user to feel disconnected from their body or environment, though this can still happen to some users.

Examples and Street Names of Drugs Classified as Hallucinogens:

Associated Risks with the Hallucinogen Drug Classification:

  • Disorganized thoughts
  • Loss of coordination
  • Nausea and vomiting
  • Dizziness
  • Irregular heartbeats
  • Paranoia
  • Anxiety
  • Unpleasant sensations

Drug Classification Based on Use


Antidepressants are medications used to treat depression, anxiety, and other related disorders. While often confused with stimulants, they do not necessarily stimulate the central nervous system, though some antidepressants can have stimulant properties as well.

In general, antidepressants act by inhibiting or stimulating different types of neurotransmitters. There are several dozens of these types of drugs and the mechanisms by which they act can be vastly different.

Examples and Street Names of Drugs Classified as Antidepressants:

  • Fluoxetine (Prozac)
  • Paroxetine (Paxil, Pexeva)
  • Sertraline (Zoloft)
  • Citalopram (Celexa)
  • Escitalopram (Lexapro)
  • Duloxetine (Cymbalta)
  • Venlafaxine (Effexor XR)
  • Desvenlafaxine (Pristiq)
  • Levomilnacipran (Fetzima)
  • Trazodone
  • Mirtazapine (Remeron)
  • Vortioxetine (Trintellix)
  • Vilazodone (Viibryd)
  • Bupropion (Wellbutrin SR, Wellbutrin XL)
  • Imipramine (Tofranil)
  • Nortriptyline (Pamelor)
  • Amitriptyline
  • Doxepin
  • Desipramine (Norpramin)
  • Tranylcypromine (Parnate)
  • Phenelzine (Nardil)
  • Isocarboxazid (Marplan)

Associated risks with the Antidepressant Drug Classification:

  • Sexual dysfunction
  • Depression
  • Anxiety
  • Constipation
  • Emotional numbness
  • Fatigue
  • Drowsiness
  • Confusion
  • Dry mouth
  • Insomnia
  • Increased appetite
  • Diarrhea
  • Jitters
  • Weight gain
  • Discontinuation syndrome

Club Drugs

Club Drugs are a loose grouping of psychoactive drugs that are intended to heighten pleasure or help someone “loosen up,” especially in the context of a club, party, concert, bar, and other similar settings. 

Some club drugs are associated with “date rape,” as they can impair higher functioning and encourage the kind of behavior that a person would not otherwise do. 

Club dugs are often mixed or taken together, which can lead to dangerous interactions.

Examples and Street Names of Drugs Classified as Club Drugs:

  • Alcohol
  • MDMA (molly, ecstasy.)
  • Ketamine (special K)
  • Flunitrazepam or rohypnol (roofies)
  • Methamphetamines (ice, speed, crystal meth)
  • Lysergic acid diethylamide (LSD, acid)
  • Phenylcyclohexyl piperidine (PCP, angel dust)

Associated Risks with the Club Drug Classification:

  • Risky sexual behavior
  • “Lost episodes”
  • Heart palpitations
  • Memory loss
  • Hallucinations
  • Dehydration
  • Diarrhea
  • Grinding and clenching of teeth
  • Sexual dysfunction
  • Irritability
  • Paranoia
  • Impulsiveness
  • Fever


Inhalants covers a wide variety of substances that can cause psychoactive effects on users when inhaled. Unlike the other categories discussed in this article, inhalants are not typically used for medical purposes or recreation. Rather, they are readily-accessible, day-to-day substances used for other applications.

The ready availability of inhalants and the low attention given to them by drug policymakers and law enforcement units have made them one of the most abused and underreported types of addictive drugs.

Examples and Street Names of Drugs Classified as Inhalants:

  • Paint
  • Glue
  • Industrial solvents
  • Gasoline
  • Medical anesthetics
  • Aerosols
  • Whippets
  • Laughing gas
  • Huff
  • Hippie crack

Associated Risks with the Inhalant Drug Classification:

  • Loss of muscle control
  • Brain damage
  • Aggression
  • Impulsiveness
  • Nausea
  • Reduced cognition
  • Nerve damage
  • Liver and kidney damage

Muscle Relaxants

Muscle relaxants are a wide category of drugs commonly prescribed to alleviate muscle spasms and pain. Occasionally, they can be abused, often by combining them with alcohol, benzodiazepines, and other drugs. 

Muscle relaxants vary in how they work on the brain and central nervous system. In most cases, they can be broadly classified as depressants, with some capable of blocking pain signals.

Examples and Street Names of Drugs Classified as Inhalants:

Associated Risks with the Inhalant Drug Classification:

  • Anxiety
  • Depression
  • Nausea
  • Fatigue
  • Loss of muscle tone
  • Sedation
  • Dry mouth
  • Loss of blood pressure

Drug Classifications Based on Legal Status

Prescription Medication

Prescription medication abuse is defined by using medication for any purpose other than what the prescribing physician defined for treatment. 

By some estimates, prescription medication abuse is more commonplace than that of illicit drugs. Of particular concern are opioids, barbiturates, stimulants, and benzodiazepines.

Examples and Street Names of Drugs Classified as Prescription Drugs:

  • Benzodiazepines
  • Methadone
  • Fentanyl
  • Codeine
  • Oxycodone HCL, hydrocodone bitartrate hydromorphone, oxymorphone, meperidine, propoxyphene, amphetamines, methylphenidate, morphine, DXM, and sleep medication.

Associated Risks with the Prescription Drug Classification:

  • Irritability
  • Violent behavior
  • Increase or decrease of appetite
  • Weight fluctuations
  • Sleep disorders
  • Depression

Illicit, Illegal, or Street Drugs

When we think of drug abuse, illicit drugs are likely the first things to come to mind. Illicit drugs refer to illegal substances which have been identified as either highly addictive or otherwise dangerous.

Examples and Street Names of Drugs Classified as Illicit Drugs:

  • Cocaine
  • Heroin
  • Methamphetamines
  • PCP
  • Cannabis
  • Ecstasy
  • Black market prescription medication

Associated Risks with the Illicit Drug Classification:

  • Weakened immune system
  • Risks of secondary infections
  • Dependence
  • Brain damage
  • Oxygen deprivation
  • Heart and lung dysfunction
  • Memory and cognition issues
  • Problems with family and professional life
  • Fatal overdose.

Why Classify Drugs?

There are limits to any drug classification system. Drugs can be classified by their chemical composition, their general effect, their legal status, and their relative addiction risks, among many possible rationales. 

The complexity of pharmacology and the effects of different substances on different individuals also makes it difficult to create a classification system that doesn’t have a lot of caveats. As a result, classification systems tend to differ based on the goals of the organizations using them.

However, classification can be useful to the general public and to policymakers, especially as a way of getting a more nuanced understanding of drug abuse and treatment. By understanding the differences between different drug categories, we not only gain a better grasp of what different substances do to the body, but we can also make better choices when it comes to treatment as well.

Find Treatment for Drugs of Any Classification

If you or a loved one are struggling with addiction to a drug of any classification, we’re here to help. Call now to speak with a treatment worker and find out more about your options.

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