Psychoactive substances: definition, examples, types, effects, and risks

Psychoactive substances are naturally occurring or synthesized substances that affect the brain and produce changes in thoughts, awareness, behaviors, and moods.

Examples of common psychoactive substances include caffeine, alcohol, nicotine, benzodiazepines, opioid painkillers, cocaine, amphetamines, MDMA or ecstasy, cannabis, and LSD. The different types of psychoactive substances are sedatives and hypnotics, stimulants, opiates, and hallucinogens and psychedelics.

The effects of using psychoactive substances are physical symptoms like altered heart and breathing rates and changes in appetite; feeling of euphoria; feelings of calmness and relaxation; increased drowsiness; enhanced mental energy; hallucinations; erratic behaviors; and confusion.

The risks of using psychoactive substances are tolerance and addiction; overdosing; development of mental health disorders; an exacerbation of the symptoms of an existing psychiatric disorder; cognitive decline; physical health issues; and a tendency to engage in risky behaviors.

What are psychoactive substances?

Psychoactive substances are substances that when introduced into the human body, produce alterations in perception, consciousness, mood, emotions, and/or cognition, as defined by the World Health Organization in a release titled “Drugs (psychoactive).” These substances occur naturally or are synthesized. They include substances with medicinal properties that are legally available, such as benzodiazepines and opioid painkillers, as well as illegal drugs like heroin and methamphetamine that have no known therapeutic benefits and are used primarily for their psychotropic properties.

Although the effects of these substances are dependent on the pattern and context of use and the individual physiological and genetic characteristics of the user, nearly all of them have the potential to cause dependence.

What are the examples of psychoactive substances?

The examples of psychoactive substances are listed below.

• Caffeine: Caffeine is the most common example of a legal psychoactive substance. It is found in coffee, tea, candy, soft drinks, and desserts. It is a stimulant that enhances energy and boosts mood. Although caffeine is generally considered safe, it is still able to cause dependence and trigger uncomfortable withdrawal symptoms upon stopping use.
• Nicotine: Nicotine is found in tobacco. It is the principal ingredient that contributes to the dependence-forming properties of smoked and chewed tobacco products. Nicotine is both a stimulant and a depressant, triggering first a rush of energy and pleasure and then causing fatigue when its effects subside.
• Alcohol: Alcohol is the most common form of depressant. Alcohol and alcoholic beverages contain ethanol, which is a psychoactive substance responsible for the dependence-forming properties of alcohol, according to a June 2024 publication by the World Health Organization, titled “Alcohol.”
• Cocaine: Cocaine is a stimulant that is illegal in a large number of countries across the world. It is highly addictive, causes multiple dangerous side effects, and has been implicated in nearly 1 in 5 overdosing fatalities, according to a publication by the Substance Abuse and Mental Health Services Administration (SAMHSA), titled “Know the Risks of Using Drugs” last updated on 30 January 2024.
• Amphetamines: Amphetamines are stimulants that are available as prescription medicines for treating attention-deficit/hyperactivity disorder and narcolepsy.
• Benzodiazepines: Benzodiazepines are prescribed as medicines to treat anxiety, insomnia, seizures, and muscle spasms. They are one of the most commonly prescribed medications, and common brands are Centrax, Xanax, Valium, Restoril, Halcion, and Librium.
• Opioid painkillers: Opioid painkillers are prescribed to treat chronic, severe pain that has failed to respond to other therapies. Common prescription opioid painkillers include oxycodone (OxyContin), hydrocodone (Vicodin), codeine, and morphine. Although safe when used as prescribed, opioid painkillers have the potential to cause substance use disorder when abused.
• LSD: Lysergic acid diethylamide (LSD) is a powerful mind-altering street drug that induces hallucinations. Its common street names are acid, blotter, blotter acid, electric Kool-Aid, purple haze, and sugar cubes.
• MDMA: Methylenedioxy-methylamphetamine (MDMA), also known as ecstasy or molly, has the properties of stimulants and hallucinogens.
• Cannabis: Cannabis, also called weed or marijuana, produces effects similar to those associated with stimulants, hallucinogens, and depressants.

What are the different types of psychoactive substances?

The different types of psychoactive substances are listed below.

• Sedatives and hypnotics: Sedatives are a class of drugs that reduce neural activity in the central nervous system (CNS) by decreasing metabolic activity in the brain or by increasing the functioning of the inhibitory neurotransmitter GABA, according to A. Dietrich in the chapter titled “Psychoactive Drugs and Alterations to Consciousness” from the Encyclopedia of Consciousness published in 2009. These drugs are also known as CNS depressants. Common examples of sedatives and hypnotics include alcohol, barbiturates, benzodiazepines, and marijuana.
• Stimulants: Stimulants are a class of drugs that produce an increase in the activity of the sympathetic division of the autonomic nervous system (ANS). These substances work by preventing the reabsorption of the neurotransmitters dopamine and norepinephrine. The halting of reabsorption results in these neurotransmitters being present for longer in the synaptic system and thereby stimulating their receptors for prolonged periods. So, the typical effects of psychostimulants are behavioral and mental arousal (Dietrich, 2009). Common stimulants include caffeine, chocolate (the psychoactive ingredient being theobromine), tea (theophylline is the psychoactive ingredient), nicotine, amphetamines, and cocaine.
• Opiates: Opiates are a class of drugs that act on opiate receptors in the brain and the digestive system to produce relief from pain and bring about feelings of euphoria (Dietrich, 2009). These substances are chemically similar to endorphins, the body’s natural pain relievers. Opiates are natural, semi-synthetic, and synthetic. Heroin and the pain reliever oxycodone (OxyContin, Percocet) are semi-synthetic opiates. Synthetic opiates include methadone and prescription pain medicines like Demerol.
• Hallucinogens and psychedelics: Hallucinogens and psychedelics are drugs with mind-expanding properties that alter sensation and perception and induce hallucinations (Dietrich, 2009). These substances are chemically similar to and imitate the actions of serotonin and epinephrine. Examples of hallucinogens and psychedelics are cannabis (marijuana), LSD, mescaline, peyote, psilocybin, and phencyclidine (PCP). These substances are not known to produce physiological or psychological dependence and thus have low addictive potential.

What are new psychoactive substances (NPS)?

New psychoactive substances (NPS) is a term used by the United Nations Office on Drugs and Crime (UNODC) to describe substances of abuse that have the potential to become a public health threat but are not yet regulated under the tenets of the 1961 Single Convention on Narcotic Drugs or the 1971 Convention on Psychotropic Substances. NPS have been commonly known on the streets as “bath salts,” “legal highs,” and “research chemicals,” according to a UNODC publication titled “What are NPS?” released as part of the UNODC Early Warning Advisory on New Psychoactive Substancesseries. NPS come in either pure or synthesized forms, and the first such substance was prepared decades ago. The term “new” indicates that these substances have become available commercially only recently.

These substances are either analogues of the existing drugs controlled by the U.N. conventions or are newly synthesized chemicals prepared to imitate the psychoactive properties of licensed and regulated drugs, according to a 2020 article by Shafi et al., published in the journal Therapeutic Advances in Psychopharmacology, titled “New psychoactive substances: a review and updates.” The major NPS substance groups are benzodiazepines, aminoindanes, fentanyl analogues, phencyclidine-type substances, synthetic cannabinoids, tryptamines, and plant-based substances like khat, kratom, and salvia divinorum, according to a UNODC release titled “NPS Substance Groups,” from the UNODC Early Warning Advisory on New Psychoactive Substances series. The UNODC notes that NPS are linked to side effects like seizures, aggression, agitation, and acute psychosis while their more serious effects include the development of dependence and severe intoxication.

What are legal drugs?

Legal drugs refer to all drugs that are obtained legally, are not sold or distributed unlawfully, and are used for the purpose for which the manufacturer intended or the physician prescribed. These include psychoactive substances like alcohol, caffeine, and nicotine; prescription drugs like sleep medications, sedative/anxiety medicines, specific stimulants, and opioid painkillers; and over-the-counter medications. However, it is common for the use of legal drugs to be regulated based on the age of the user, the specific jurisdiction where the substance is sold and/or used, and driving regulations. Countries are known to regulate and control the amount of active ingredients in legal drugs, such as the alcohol content in drinks and the amount of nicotine in cigarettes. Using legal drugs illegally–either excessively or for a purpose for which the substance was not intended–is associated with adverse health complications.

How are psychoactive substances used?

Psychoactive substances are used in diverse settings and for a multitude of purposes, such as to manage physical and mental health issues, alleviate emotional stress and elevate mood and/or achieve a state of euphoria, improve sleep, induce altered states of consciousness, improve performance at school or the workplace, and establish drug instrumentalization. Psychoactive drugs are used medicinally. Individuals use prescription opioid painkillers to manage chronic pain; benzodiazepines, sedative/hypnotics, and barbiturates to alleviate anxiety and/or improve sleep; and stimulants like amphetamines to treat attention-deficit/hyperactivity disorder and narcolepsy.

Caffeine, the most widely used psychoactive substance in the world, is taken to increase mental alertness. Students at higher educational institutions are known to use stimulants to improve cognitive abilities, such as attention and memory, and decrease physical and mental fatigue, according to a 2020 article by Boclin et al., published in the Sau Paulo Medical Journal, titled “Academic performance and use of psychoactive drugs among healthcare students at a university in southern Brazil: cross-sectional study.” A significant percentage of psychoactive substance users take these drugs to achieve feelings of euphoria. According to a 2015 article by Christian P. Müller and Judith R. Homberg published in the journal Behavioural Brain Research, titled “The role of serotonin in drug use and addiction,” there are users who consume psychoactive drugs not to derive pharmacological or psychotropic benefits but to facilitate specific non-drug dependent behaviors or establish “drug instrumentalization.” These behaviors include social behaviors, sexual behaviors, and stress and anxiety management.

Psychoactive drugs, such as hallucinogens, are also used in religious and/or shamanic settings to induce alterations in consciousness and perception, as mentioned by Glenn Shepard in the chapter titled “Psychoactive Botanicals in Ritual, Religion, and Shamanism” from the 2005 book “Ethnopharmacology: Encyclopedia of Life Support Systems (EOLSS).”

What are the effects of psychoactive substances?

The effects of psychoactive substances are listed below.

• Physical effects: CNS depressants reduce heart rate and respiration. Stimulants increase heart and breathing rates and appetite. These symptoms are potentially fatal. For instance, methamphetamine, which speeds up the body’s functions, is known to cause death even on the first use, according to a publication by the Substance Abuse and Mental Health Services Administration (SAMHSA), titled “Know the Risks of Using Drugs” last updated on 30 January 2024. Cocaine is associated with heart attacks and sudden death, even on the first try.
• Feelings of euphoria: Heroin, cocaine, and amphetamines produce feelings of euphoria. The drugs trigger a rush of dopamine that reinforces the link between the consumption of the substance and the feeling of euphoria, according to a July 2011 release by the National Institute on Drug Abuse, titled “Drugs, Brains, and Behavior: The Science of Addiction-Drugs and the Brain.”
• Feelings of relaxation and calmness: Substances like barbiturates and benzodiazepines decrease mental stress and induce feelings of relaxation and calmness.
• Increased mental energy: Stimulants like caffeine and amphetamines are known to increase mental alertness and improve focus.
• Increased sleepiness: Sedatives and hypnotics, alcohol, and heroin induce drowsiness or sleep. Increased sleepiness is dangerous if the individual is driving or operating heavy machinery.
• Hallucinations: LSD, cannabis, and MDMA have hallucinogenic effects. Users are known to see, hear, and feel things that do not exist in reality.
• Confusion: Psychoactive substances like alcohol and heroin are associated with symptoms like clouded thinking and impaired judgment.
• Erratic behaviors: Users taking psychoactive substances like alcohol, cocaine, and amphetamines are known to manifest erratic behaviors like violence, paranoia, panic, aggression, and psychosis.

How do psychoactive substances affect the brain?

Psychoactive substances affect the brain by altering synaptic transmission in the central nervous system, according to A. Dietrich in the chapter titled “Psychoactive Drugs and Alterations to Consciousness” from the Encyclopedia of Consciousness published in 2009. Synaptic transmission is the process that takes place at the synapses whereby neurons communicate with one another via a chemical agent called a transmitter, which is released by a presynaptic neuron. After being released, the neurotransmitter diffuses to the postsynaptic cells where it binds to a specific receptor. It then generates a signal to stimulate or inhibit the activity of the postsynaptic cell. Psychoactive substances impact synaptic transmission in two ways: by regulating the amount and availability of neurotransmitters and by influencing the functionality of a neurotransmitter receptor.

Psychoactive drugs like opioids, cannabinoids, and nicotine imitate the effects of a neurotransmitter. Opioid drugs like heroin, methadone, fentanyl (Actiq and Fentora), codeine, hydrocodone (Vicodin), and oxycodone (OxyContin, Roxybond) bind to opioid receptors in the brain to block sensations of pain and induce feelings of pleasure. Psychoactive drugs like cocaine and amphetamines stimulate the effects of neurotransmitters, according to a 2021 article by da Silva et al., published in the journal Current Opinion in Toxicology, titled “Neurotoxicity of psychoactive substances: A mechanistic overview.”

For instance, cocaine increases the availability of the dopamine neurotransmitter and induces symptoms like feelings of pleasure and being rewarded, increased energy, and enhanced arousal, according to a 2015 article by Vivek Verma published in the journal Clinical Psychopharmacology and Neuroscience, titled “Classic Studies on the Interaction of Cocaine and the Dopamine Transporter.”

Another example of drug impact on the brain is observed when psychoactive substances like alcohol reduce the effects of neurotransmitters. For instance, glutamate is an excitatory neurotransmitter. Alcohol inhibits glutamate activity in the brain by blocking its receptors in the postsynaptic neurons, according to a 2014 article by Niladri Banerjee published in the Indian Journal of Human Genetics, titled “Neurotransmitters in alcoholism: A review of neurobiological and genetic studies.” Reduced glutamate activity is responsible for the sedative effects of alcohol.

How long do the effects of psychoactive substances last?

The length of time for which the effects of psychoactive substances last varies on the amount and strength of the drug taken, the individual’s body weight and how quickly they are able to metabolize substances, their tolerance levels, and whether the drug was mixed with other substances. The duration of the effects of drugs like opioids, benzodiazepines, and barbiturates varies according to the type of the substance used.

For instance, opioids like heroin and codeine are detected in a sample of urine for up to 48 hours while morphine is detected for up to 48-72 hours. Oxycodone is detectable in urine for up to 2-4 days and methadone, for up to 3 days. Short-acting benzodiazepines like lorazepam are detectable in urine for up to 3 days while longer-acting ones like diazepam show up in urine toxicology screens for up to a month. The effects of cocaine last for 30-45 minutes, but the substance is detectable in urine for up to 2-3 days. For the majority of users, the effects of alcohol last about an hour, but the substance is detectable in urine for up to 72 hours. The effects of cannabis last for 1-4 hours when the substance is smoked and for 4-12 hours when it is consumed by mouth. Its presence is detected in urine for up to 10-30 days and longer in case of heavy usage. Methamphetamine’s effects last 4-12 hours, but the substance continues to show up in urine samples for up to 2-5 days. The effects of MDMA last 3-4 hours while the substance is detectable in urine samples for up to 3-4 days. The effects of LSD last for up to 12 hours while it is detected in an urine sample for up to 3 days.

What are the risks of using psychoactive substances?

The risks of using psychoactive substances are listed below.

• Developing tolerance and addiction: Use of psychoactive substances is associated with an increased risk of developing tolerance and addiction in vulnerable populations, as noted in the chapter “THE NEUROBIOLOGY OF SUBSTANCE USE, MISUSE, AND ADDICTION” from the 2016 publication by the Substance Abuse and Mental Health Services Administration (SAMHSA), titled “Facing Addiction in America: The Surgeon General’s Report on Alcohol, Drugs, and Health [Internet].”
• Development of mental health disorders: There is research to suggest that abusing alcohol increases the risk of an individual developing post-traumatic stress disorder by hindering their ability to heal from traumatic experiences. Marijuana is known to contribute to the development of schizophrenia in genetically vulnerable individuals (SAMHSA, 2016). This is because psychoactive drug abuse triggers neuroadaptations in brain regions that are also involved in other psychiatric illnesses, such as anxiety, mood, or impulse-control disorders, and schizophrenia, according to a 2020 publication by the National Institutes on Drug Abuse, titled “Common Comorbidities with Substance Use Disorders Research Report.”
• Aggravation of the symptoms of a mental illness: Psychoactive substances are known to exacerbate the symptoms of a co-occurring mental illness by disrupting the normal and healthy functioning of the neural mechanisms associated with experiencing pleasure or reward, perceiving stress, and regulating impulses (SAMHSA, 2016). For instance, alcohol, a CNS depressant, worsens the symptoms of a mood disorder and triggers rebound anxiety.
• Cognitive decline: Addiction to psychoactive substances affects neural mechanisms and brain regions that overlap extensively with those associated with cognitive functions like memory, learning, and reasoning, according to a 2010 article by Thomas J. Gould published in the journal Addiction Science & Clinical Practice, titled “Addiction and Cognition.”
• Development of physical health issues: The long-term risks of using psychoactive drugs are the development of cardiovascular issues, kidney or liver damage, and respiratory difficulties. Using cocaine is associated with health risks like developing asthma, bowel decay, and HIV, according to a publication by the SAMHSA, titled “Know the Risks of Using Drugs” last updated on 30 January 2024.
• Overdosing: Increased tolerance and loss of control over the use of psychoactive drugs escalate the risk of overdosing, which is potentially fatal. Excessive intake of psychoactive drugs in one sitting is also associated with intoxication that manifests as potentially life-threatening symptoms like seizures, increased blood pressure, rapid heart rate, and elevated body temperature.
• Engaging in illegal or risky behaviors: The mind-altering properties of psychoactive drugs like alcohol, hypnotics, sedative-tranquilizers, and narcotics increase the risk of individuals losing inhibition and engaging in risky and/or illegal behaviors. These behaviors include driving under the influence of alcohol or engaging in unprotected sex. The cognitive decline caused by the abuse of psychoactive drugs is also known to make users engage in risky behaviors that are harmful to them and to those who come in contact with them.

Are psychoactive substances dangerous?

Yes, psychoactive substances are dangerous because these drugs have addictive properties and lead to dependency and addiction if used improperly. Psychoactive substances have varying degrees of risk and dependency profiles. For instance, legal drugs like caffeine, alcohol, nicotine, and prescription medications are safe if used responsibly. Although caffeine has low addiction potential, nicotine is highly addictive while legally prescribed benzodiazepines have moderate addiction potential. Legal drugs, too, like nicotine, alcohol, and cannabis are associated with several types of cancer. So, users of psychoactive drugs must not be guided by terms like “legal” and “illegal.”

It is also erroneous to presume that unregulated new psychoactive substances that are commonly known as “legal highs” are safer than illegal drugs. Authors Golembiowska et al., in a 2015 article titled “Effect of Some Psychoactive Drugs Used as ‘Legal Highs’ on Brain Neurotransmitters” published in the journal Neurotoxicity Research warn that “legal highs” have the potential to cause life-threatening complications.

Can psychoactive substances cause addiction?

Yes, psychoactive substances can cause addiction in vulnerable individuals by producing structural, functional, and chemical changes in the brain’s reward system and regions associated with learning, memory, reasoning, and impulse regulation, according to a 2010 article by Thomas J. Gould published in the journal Addiction Science & Clinical Practice, titled “Addiction and Cognition.” According to the author, disruptions in these critical neural circuits are not only associated with cravings and drug-seeking behaviors but are also implicated in mechanisms that hinder the acquisition and development of adaptive behaviors that support sobriety.

The risk of progressing from controlled use of psychoactive drugs to compulsive and uncontrolled drug-use behaviors that characterize addiction is especially high in individuals who have pre- and/or co-morbid pathology, such as the presence of psychiatric disorders like depression, anxiety, and obsessive-compulsive disorder, according to a 2015 article by Christian P. Müller and Judith R. Homberg published in the journal Behavioural Brain Research, titled “The role of serotonin in drug use and addiction.” Psychoactive substances pose an increased risk of causing addiction in individuals who have had adverse childhood experiences and/or possess specific genetic characteristics, as noted in the chapter “THE NEUROBIOLOGY OF SUBSTANCE USE, MISUSE, AND ADDICTION” from the 2016 SAMHSA publication titled “Facing Addiction in America: The Surgeon General’s Report on Alcohol, Drugs, and Health [Internet].” The adolescent brain is vulnerable to the effects of psychoactive drugs. Individuals who start using these substances during adolescence have an increased risk of developing addiction compared to those who start using at an older age.

How can addiction to psychoactive substances be prevented?

Addiction to psychoactive substances can be prevented by acknowledging the presence of problematic substance use behaviors, avoiding drug triggers, managing stress and/or the negative symptoms of another psychiatric disorder without using drugs, and living a balanced life with healthy habits, inspiring goals, and enjoyable and meaningful pursuits. Denial is common among substance users with problematic drug use habits. Recording instances of substance use and the triggers that tend to precipitate use helps acknowledge that there is a problem that needs to be addressed. This record is also helpful in identifying drug triggers. Drug triggers are people, places, social situations, and emotions that act as drug cues. So, avoiding people who tend to exert pressure to consume drugs and not visiting places where drugs are likely to be available are helpful strategies for avoiding temptations.

Peer pressure plays a significant role in influencing drug use behaviors in adolescents and young adults. It has been found that individuals who were subjected to peer pressure to use drugs engaged more in binge drinking and sustained alcohol and marijuana use throughout their lifetimes compared to those who did not perceive peer pressure, according to a 2020 article by Keyzers et al., published in the journal Substance Use & Misuse, titled “Peer Pressure and Substance Use in Emerging Adulthood: A Latent Profile Analysis.” It is helpful to forge healthy social connections and form relationships and/or interact with individuals who do not use drugs.

Recording substance use habits is helpful in determining if an individual is using psychoactive drugs to self-medicate and deal with negative moods and emotions. Learning healthy coping strategies that do not involve the use of drugs is the best way to stop self-medicating, a practice that is common among individuals with mental health disorders like depression and anxiety.

Taking the help of a professional counselor or therapist is essential for addressing mental health issues, especially if there is a psychiatric disorder present. The presence of a mental illness increases the risk of an individual developing an addiction to substances, as noted in the chapter “THE NEUROBIOLOGY OF SUBSTANCE USE, MISUSE, AND ADDICTION” from the 2016 SAMHSA publication titled “Facing Addiction in America: The Surgeon General’s Report on Alcohol, Drugs, and Health [Internet].” Practicing relaxation techniques like yoga, meditation, and deep breathing helps uplift the mood and reduces emotional stress.

Physical exercise is known to be a mood booster while getting adequate sleep at night is known to improve symptoms of mood disorders. Having a purpose in life, setting goals and striving to achieve them, and finding joyful activities to engage in that do not involve the use of drugs are ways to distract oneself from the lure of drugs.