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    Drug classifications are used to organize drugs into different categories. The most common categories make up drugs that have similarities based on chemical makeup, effects of the drug, and legality.

    The same drug may be classified under two different classification systems. Some drugs may be grouped together under one classification, but not another. There is much disagreement regarding how drugs should be classified, making it difficult to create one set of drug classifications.

    Drug Classifcations Based on Chemical Makeup

    Classifications based on chemical makeup categorize drugs based on their chemical similarity. Drugs that are prescription and illegal can be categorized into 6 different types based on the chemicals inside the drugs alone. Addiction to one drug can increase the risk of developing an addiction for another drug that has a similar chemical makeup.


    A majority of American adults, 86.5 percent, have consumed alcohol at some point in their lifetime1. Alcohol is a central nervous system depressant which can slow activity in the brain . Drinking can cause affects on mood, behavior, memory, and clear thinking. Alcohol can also impact coordination, raise blood pressure, and increase heart rate2.

    Different types of alcohol include3:

    Overtime, excessive and chronic alcohol use can lead to severe problems, including4:


    Opioids are a class of drugs that naturally occur in the opium poppy plant. Opioids produce several effects in the brain, including pain relief.

    Doctors prescribe opioids as painkillers because they can block pain signals between the brain and the body. Opioids can also produce feelings of relaxation and feeling high and create slowed breathing, constipation, nausea, confusion, and drowsiness.

    The most common opioids include5:

    Excessive opioid use can lead to5:


    Benzodiazepines are a class of drugs often prescribed by doctors to treat anxiety. These drugs appear to work by affecting the brain’s neurotransmitters, chemicals released by nerves to communicate with other nerves. One of the neurotransmitters is gamma-aminobutyric acid (GABA), which suppresses the activity of nerves and can reduce anxiety6.

    Benzodiazepines are also effective in treating seizures and insomnia. They are also used for general anesthesia, sedation before surgery, muscle relaxation, alcohol withdrawal, nausea and vomiting, depression, and panic attacks.

    Types of benzodiazepines include6:

    Effects of benzodiazepines can include6:

    Benzodiazepines can also create a physical dependence that can be associated with negative symptoms when stopping this drug. Withdrawal symptoms can be experienced after stopping daily use suddenly. Symptoms of withdrawal can include agitation, insomnia, and lacking self-worth.

    After more than a few months of use, stopping benzodiazepines can cause seizures, tremors, muscle cramping, vomiting, and sweating. Slowly tapering off of these medications can lessen or eradicate withdrawal symptoms6.


    Cannabinoids are a class of drugs that naturally occur in the Cannabis sativa plant. The most well-known of the cannabinoid compounds is THC, the primary psychoactive ingredient in cannabis. Additionally, cannabidiol (CBD) makes up about 40% of the plant resin extract7.

    Cannabinoids work by interacting with cannabinoid receptors on the surface of cells in the brain. These receptors are located in different parts of the central nervous system, and two main types are CB1 and CB2.

    Types of cannabinoids include7:

    Effects of cannabinoid use are dependent on the brain area the cannabinoid interacts with. Effects on the limbic system can include memory alteration, cognition challenges, and issues with psychomotor performance. Effects on the mesolimbic pathway can include impacts to reward responses, pleasure responses, and pain perception. 


    Barbiturates are a central nervous system depressant that can treat insomnia, seizures, and headaches8. All barbiturates affect the gamma-aminobutyric acid (GABA) neurotransmitter, which suppresses the activity of nerves. These medications can cause muscles to relax, and a reduction in heart rate, breathing, and blood pressure.

    Examples of barbiturates include9:

    Effects of barbiturates can include9:

    Barbiturates can also be habit-forming, as they are highly addictive drugs9. These drugs are not commonly used in the United States today because of the innovation of benzodiazepines. Benzodiazepines are believed to have less harmful side effects and produce a similar result to barbiturates.

    Drug Classifications Based on Effect

    Classifications based on effect categorize drugs based on how they affect the mind and body. These different classifications can help determine how the drug may affect the central nervous system. Classifying drugs in this way can help with treatment and developing different harm-reduction techniques.


    Depressants are a class of drugs that reduce arousal and stimulation. These drugs impact the central nervous system, causing messages between the brain and the body to slow. Depressants can create a feeling of euphoria, as they cause the user to feel more relaxed and less inhibited.

    Examples of depressants include10:

    When taking low or small doses of depressants, the effects can include10:
    When taking higher doses of depressants, the effects can include10:


    Stimulants are drugs that speed up the messages sent between the brain and the body11. This increase in activity creates alertness, attention, and energy in the individual using the stimulant. Stimulants can be used medically or recreationally and some stimulants are illegal.

    Examples of stimulants include12

    Low doses of stimulants can create effects including11:

    High doses of stimulants can create effects including11:
    Stimulants are highly addictive and have a high potential for abuse. Long-term and excessive use of stimulants can create adverse effects11.


    Hallucinogens are a class of drugs both extracted from plants and mushrooms and man-made. This class of drugs can change perceptions of surroundings, thoughts, and feelings. Hallucinogens can cause hallucinations, which are sensations or images that seem real even though they are not13.

    Hallucinogens work by temporarily disrupting the communication between the brain and body. Interference with serotonin and glutamate can be common with these drugs depending on the type. Serotonin regulates mood, sensory perception, sleep, hunger, body temperature, and sexual behavior. Glutamate regulates pain perception, emotion, learning, and memory.

    Examples of hallucinogens include13:

    Short-term effects of hallucinogens include13:
    Long-term effects of hallucinogens include13:
    The long-term effects of hallucinogens occur most frequently when a history of mental health disorders is present. Hallucinogens are generally less addictive than other drug classes but can have more intense short-term and long-term effects13.


    Inhalants are a class of drugs, including volatile substances that produce vapors creating psychoactive, or mind-altering, effects when inhaled. There are many different inhalants, including volatile solvents, aerosols, gasses, and nitrites.
    Inhalants are often found in household, industrial and medical products. Most of these drugs produce feelings of being high, regardless of the type.

    Examples of commonly abused inhalants include14:

    Effects of sniffing inhalants include15:

    Sniffing inhalants is even more dangerous when done in enclosed places or indoors or when mixed with other drugs. Running or engaging in other physical activity after sniffing can cause cardiac arrest, sometimes resulting in death.

    Existing health problems can also increase the dangers associated with sniffing. Overdose and sudden sniffing death are also risks of using inhalants. Sudden sniffing death is extremely rare15.

    Drug Classifications Based on Legality

    The Federal Government passed the Controlled Substance Act (CSA) in 1970. The CSA classifies drugs into five schedules based on the drug’s acceptance for medical use, the potential for abuse, and the potential for dependence16.

    Each Schedule is associated with different rules and regulations for the drugs’ production, sale, possession, and use. Each Schedule also has specific punishments for violating the rules related to the drugs in that Schedule.

    Each state within the U.S. has a version of drug classification schedules and can vary from the Federal schedules. Additionally, there has been a lot of debate regarding what specific Schedule each drug should belong to.

    Schedule I

    Drugs classified as Schedule I have a high potential for abuse and severe dependence. No drugs in this classification are approved for medical use, and possession of any of them is illegal16.

    Examples of Schedule I drugs include17:

    Schedule II

    Drugs classified as Schedule II also have a high potential for abuse and severe dependence. Unlike Schedule I drugs, there are accepted medical uses for some Schedule II drugs. There are legal prescriptions for these drugs, but they come with heavy regulations for medical use considering their dangers16.

    Examples of Schedule II drugs include17

    Schedule III

    Drugs classified as Schedule III have a moderate potential for abuse and dependence. They also have accepted medical uses, which means that legal prescriptions for these drugs are available16.

    Examples of Schedule III drugs include17:

    Schedule IV

    Drugs classified as Schedule IV have a low potential for abuse and dependence. They have approved medical uses, and it is possible to get a legal prescription for these drugs16.

    Examples of Schedule IV drugs include17:

    Schedule V

    Drugs classified as Schedule V have an even lower potential for abuse than Schedule IV and a low potential for dependence. They have accepted medical uses, and it is possible to obtain a legal prescription for these drugs16.

    Examples of Schedule V drugs include17:

    Treatment Options for Different Drugs

    Several treatment options can successfully treat addiction to any drug in any classification or Schedule. Treatments that can help with addiction include behavioral counseling, medication, treatment of co-occurring mental health disorders, and relapse prevention plans18.

    Some different drug classifications may require medications for relapse prevention based on the type of drug. These medications can help reduce cravings and re-establish normal brain functioning. Drug classifications with current medications for relapse prevention include opioids, alcohol, and tobacco18.


    Current medications used to treat opioid addiction include methadone, buprenorphine, and naltrexone. Methadone and buprenorphine act on the same brain areas as heroin and morphine, resulting in decreased withdrawal symptoms and cravings18.

    Naltrexone blocks receptor sites for opioids in the brain. This medication is often used to help eliminate the effects of opioids when opioids are used. Naltrexone can be used after the detoxification process has been complete18.

    All medications used to treat opioid addiction reduce individuals’ drug-seeking habits and associated criminal behavior. These medications can also help willingness to engage in behavioral treatments18.


    Approved medications for treating alcohol addiction include naltrexone, acamprosate (Campral), and disulfiram (Antabuse)18. Naltrexone works by blocking opioid receptors associated with alcohol cravings and the rewarding effects of drinking alcohol. This medication can be highly effective in reducing relapse for some patients and in others genetic differences can impact its effectiveness18.

    Acamprosate (Campral) can reduce the symptoms of long-lasting alcohol withdrawal, including insomnia, anxiety, restlessness, and dysphoria. This medication may be a more effective treatment for severe alcohol addiction18.

    Disulfiram (Antabuse) creates negative symptoms when an individual drinks alcohol and interferes with the way alcohol breaks down in the body. This drug can cause flushing, nausea, and irregular heartbeat when alcohol is ingested. When the desire to stop drinking is strong this medication can be helpful18.


    Nicotine replacement therapies include the patch, spray, gum, and lozenges. Prescription medications are effective in preventing relapse like bupropion (Zyban) and varenicline (Chantix). Behavioral therapies, such as group and individual therapy, can enhance medication effectiveness18.

    Receive Treatment for Drug & Alcohol Abuse

    Drugs are commonly classified based on chemical makeup, effect, and legality. Based on the classification of drugs abused, an individualized treatment plan can be established. Treatment for all drug addictions may be based on the drug classification to best treat symptoms of withdrawal and dependence.

    If you or a loved one are suffering from an addiction to drugs, reach out to ReAlign Detox today. Our team can answer any questions you may have and give you a better understanding of our program.

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