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What are the Most Widely Used Illicit Drugs?

Written by Brandon Okey. Mina Draskovic, B.Psy., reviewed this content for accuracy.

Every American has heard talk of drug abuse and illicit drug use in their lifetime. What kind of drugs do these include? While some define illicit drugs as strictly substances that are illegal to use, make, or sell by law, the term “illicit drugs” is often used to include all substances that stimulate or inhibit the central nervous system or cause hallucinations.

Global and National Statistics

Globally, it’s recorded that about 5% of the population has used an illicit drug at least once in their life. This means around 269 million people worldwide have consumed illegal drugs. Additionally, 35.6 million of those users are considered addicts or drug abusers. In our country, the percentage of drug users is even higher. As of 2017, it was estimated that 11.2% of (or 53.2 million) Americans over age 12 had used an illicit drug in the past month, a number that is up from 9.2% in 2012. In 2019 it was determined that 3.5% of illicit drug users were specifically abusing prescription drugs.

Most Widely Used Illicit Drugs

Let’s look at some of the illicit drugs included in these statistics:


Cocaine is an addictive stimulant in powder form. It is usually snorted or injected and it produces an energy high or sense of euphoria. As many as 1,800 Americans try cocaine for the first time every day.

Crack Cocaine

Crack cocaine is a purer and more intense form of cocaine that is usually smoked, which allows it to provide the user a quicker and more intense high. Because of its potency it has extremely high rates of overdose even in first time users.


Ecstasy is commonly referred to as a party or rave drug, and is consequently most popular among young people. It produces an effect of heightened senses and lowered inhibitions. While the high on ecstasy can last for a few hours, the letdown can last for days.


Hallucinogens include several substances, including LSD, mushrooms, and PSP. Often these drugs create an “out of body” feeling accompanied by visions or hallucinations. While these drugs are often less addictive than some of the others on this list, they can still be incredibly harmful because frequent users will try higher and higher doses as they gain a dependency on the substance.


Heroin is one of the most dangerous and addictive drugs in the world. It is a potent opiate that provides a temporary sense of well-being and decreased anxiety. Because the drug interferes with the brain’s dopamine neurotransmitters, heroin users get addicted extremely quickly. One in four first time users of heroin will develop an addiction and it is one of the most commonly overdosed drugs known to man.


Inhalants include household solvents from cleaners to gasoline, as well as aerosols, gases, and nitrates. They can cause a temporary hallucinatory state or have a similar effect to alcohol. Though less common than other drugs, inhalants are used much more frequently by teenagers.


Though not technically illegal in most places, alcohol is often considered an illicit drug because of its addictive nature. In fact, alcoholism is considered the second most common addiction in the U.S. Alcohol lowers inhibitions and can be used safely in moderation, but often leads to severe addiction that can ruin lives. Substance abusers also pair alcohol with other drugs leading to extremely dangerous effects in the body.


Marijuana is a drug that is smoked or eaten in the form of “edibles”. It is considered the most widely used illicit drug in the world, with 43.5 million Americans having used it at least once in the year 2018. Marijuana produces a gentle high with reduced anxiety. Marijuana is a particularly controversial substance, because it is becoming legal in more and more states for both medical and recreational use. Because there is no risk of overdosing on marijuana, it is often considered less dangerous than other illicit drugs. However, marijuana can still be an addictive substance, and much like alcohol, should only be used legally in moderation.


Ketamine is another illicit drug that is occasionally used in a controlled medical environment. It is an anesthetic that produces a particularly short high in users. People who have used ketamine describe it as a blissful experience with an out-of-body feeling. Those who abuse ketamine are usually unable to overcome their addiction without professional help.


Though legal, tobacco is one of the most addictive substances we know of because of its nicotine content. Nicotine addiction is the most common addiction in America, with approximately 50 million users daily. Tobacco use provides less of a traditional “high” in users, but is common among youth and hard to quit without help.


Meth is an incredibly addictive illicit drug that produces a surge of dopamine in the brain. It is one of the most dangerous substances in the world in part because of the ill-effects it has on a user’s body, including skin sores, tooth decay, seizures, heart attack, and increased risk of HIV/AIDS. Any use of meth is extremely dangerous and warrants intervention.


Benzodiazepines are a class of prescription drug that are used to treat many mental disorders, including panic attacks, epilepsy, and anxiety. Benzos relax the body and reduce stress, but they should only be used for a short amount of time and in a controlled environment. Unfortunately when abused, they become addictive and users can suffer severe withdrawal symptoms.


Like benzos and ketamine, opiates are prescription drugs meant to be used in controlled and temporary situations. They include any drug made from opium, and are also referred to as “prescription painkillers”. Hydrocodone, oxycodone, morphine, and codeine are among the most commonly used opiate drugs. Though legal when prescribed, there is a wide market for illicit use of opioids. In 2012 it was estimated that 259 million opioid painkillers were legally prescribed. Of those, nearly 2 million people would go on to develop an opioid addiction. Most people who end up with an opioid addiction don’t realize they have a problem until they try to stop using the medication. In 2016 over 42,000 people in the U.S. died from opioid overdose.

Illicit Drug Effects and Abuse

All illicit drugs can have serious health risks, some even when taken in small doses. Several drugs can lead to addiction after a first time use. All people who face drug addiction to illicit substances are at risk of overdose, which is often fatal. Many who try to quit on their own end up relapsing and overdosing then, because they think they need the same dose they used previously and their body is no longer used to that amount. The risk of overdose especially increases for people using illicit drugs through injection. Heroin and opioids are particularly vulnerable to relapse and subsequent overdose. The number of deaths related to these two illicit substances has increased substantially over the last ten years. From 2002 to 2017, the number of opioid-related deaths grew by over 4 times. Repeated use of illicit drugs can impose short and long term consequences. Substance abuse causes dramatic changes to the brain, which can affect more than just a person’s physical health. These psychological changes may lead to erratic behavior, mental illness, and self-destructive life choices. Substance abuse and addiction leads to:
  • Relationship damages between users and family, friends, and romantic partners
  • Neglecting work responsibilities and goals
  • Trouble staying on top of obligations and schedules
  • Failing grades or dropping out of school
  • Financial hardship due to spending money on a drug habit
  • Legal consequences for drug possession

Treatment for Illicit Drug Use

There are several kinds of treatment for someone suffering from illicit drug addiction. Some of these include:
  • Detox supervision and support
  • Behavioral counseling
  • Medication to aid withdrawal symptoms
  • Dual diagnosis for mental health issues
  • Long term follow-up to prevent relapse
  • Yoga, mediation, and other somatic strategies
It is important to remember that no one treatment will work for every user. Effective treatment addresses all of a patient’s needs, not just their medical ones. Medically assisted detoxification is usually the first step of treatment, but afterward a combination of different strategies will be necessary to ensure a patient is truly recovered and able to move forward with their life free of addiction and drug use.

Ardu Recovery Center

At Ardu Recovery Center we know that addiction is a complex, but treatable disease. Our treatment approach tailors a variety of medical and holistic practices to your specific needs. During each step of your recovery we will be there to provide constant support and direction from your personal treatment team. We feature programs designed specifically for men, women, and young adults. At our beautiful facility in Provo, Utah, we believe that you have the power to heal. Reach out today if you or a loved one is ready to recover.
Brandon Okey

Brandon Okey is the co-founder of Ardu Recovery Center and is dedicated to empowering people on their journey to sobriety.