According to SAMHSA, nearly one in 10 people have tried an illicit substance, which amounts to 27 million people, and those individuals are starting young. Slightly more than nine percent of individuals between the ages of 12 and 17 today have used an illicit substance. For individuals between the ages of 18 and 25, usage increases to 22 percent.


Commonly used illicit substances include heroin, cocaine, crack, marijuana, hallucinogens, and inhalants. These substances are often used for their mind-altering or numbing effects. Some individuals may even try to self-medicate a mental disorder with substances rather than seeking professional treatment. Understanding the most common illicit substances and their effects can help you recognize the symptoms of addiction and seek treatment.

Prevalence Of Illicit Substance Use In The U.S.

SAMHSA states that illicit substance abuse is still a major problem in the United States with more than 23.5 million individuals seeking treatment for a substance use disorder, which is characterized by the chronic use of an illicit substance.  Usage affects the mental and physical health of the individual as well as work and family relationships.

While some illicit substances have decreased in popularity, marijuana and heroin use have increased. In the past year, 13.36 percent of all individuals over the age of 12 have used marijuana, which is a .016 percent increase, according to SAMHSA Table 1. In Colorado, the District of Columbia, and Vermont, more than 20 percent of individuals over the age of 12 have used marijuana in the past year.

Nearly two percent of all individuals over the age of 12 have used heroin within the past year, and .70 percent of 8th graders have tried heroin, according to the National Institute on Drug Abuse. Modern versions of heroin are often cut with Fentanyl, which is leading to an increase in overdose deaths. The CDC reports that from 2000 to 2013, overdose deaths from heroin increased from .07 per 100,000 to 2.7 deaths per 100,000 individuals.

Thankfully, substance abuse disorder can be effectively treated and individuals can recover from their disease and move forward to live productive and healthy lives. When addicted individuals and their family members understand the signs and symptoms of substance abuse disorder, including changes in behavior and appearance, inability to maintain a job, and constantly seeking out and maintaining a supply of their drug of choice, securing treatment becomes easier.

Common Illicit Substances

Use of illicit substances can also greatly decrease the individual’s health, leading to an increased risk of heart attacks, strokes, organ failure, brain damage, and/or damage to the central nervous system. If you or someone you love has a problem with a substance use disorder, it is imperative to seek treatment at a qualified and experienced rehabilitation center.

Read more information on the commonly abused illicit drugs below.

Cocaine is an extremely powerful stimulant that is derived from coca plant leaves. This highly addictive, illicit substance is most commonly snorted as a powder. However, it can also be smoked and injected. Chronic cocaine use can lead to irregular heartbeat, high blood pressure, and chest pain. Chronic cocaine use can increase the risk of heart attacks and strokes.

Crack Cocaine
Crack cocaine is a form of cocaine that looks like rocks or crystals and is often smoked to achieve a high. This drug is considered more addictive than the powder form of cocaine, and like cocaine, it can damage the circulatory system, increasing the individual’s heart rate and risk of having a heart attack or stroke. Individuals who use crack may also experience depression and anxiety after the high and muscle convulsions.

Cough Syrups And Cold Medications
While cough syrups and cold medications can be purchased over-the-counter in many retail locations, they are also misused by individuals seeking a high or altered state of mind. Commonly misused cold medications include cough syrups containing DXM, Pseudoephedrine (Sudafed, which can be used to make methamphetamine) and cough syrups containing codeine. Misuse of these substances can cause constipation, drowsiness, and decreased breathing as well as dangerous overdoses.

Ecstasy/ Molly (MDMA)
Ecstasy is often referred to as MDMA or Molly. It is an illicit substance that first gained traction as a club drug. The drug is often pressed into colorful tablets that can either be swallowed or crushed and snorted. Individuals who use MDMA experience reduced inhibitions and enhanced perceptions. Long-term use can lead to mental health issues, like depression, confusion, and problems with memory, focus, and sleep.

The term hallucinogen is used to describe a class of illicit drugs that causes a significant change in the way an individual perceives auditory and visual stimuli. The individual may also hear and see things that are not there. Hallucinogenic drugs include ayahuasca, DMT, LSD, peyote, psilocybin, and salvia. Individuals may experience hallucinations and mood swings long after taking the drug.

Heroin is an extremely addictive opioid that is derived from the Asian poppy. While Heroin is most commonly injected, it can also be smoked and snorted. Individuals who use the illicit substance feel euphoria. Long-term effects, especially when used intravenously, include collapsed veins, infections, constipation, and stomach cramps.

The term inhalant refers to a class of substances that are inhaled. Commonly inhaled substances include canned air, gasoline, lighter fluid, permanent markers, paint thinner, super glues, and cleaning chemicals. These substances are typically used for their euphoric effects. Short-term use causes slurred speech, dizziness, lightheadedness, and a loss of coordination. Long-term use can lead to muscle spasms, brain damage, kidney damage, and liver damage. Certain inhalants can also cause heart failure.

Marijuana, while legal in some states and occasionally prescribed for medical use, can still lead to substance abuse disorder. In states where marijuana use is not legal or medically prescribed, it is still an illicit substance. Marijuana can be smoked, eaten, or used as an oil. It is considered a mild hallucinogenic. Individuals who use marijuana typically experience increased hunger, memory problems, and a decrease in coordination and memory problems.

Methamphetamine (Crystal Meth)
Methamphetamine, or Crystal meth, is a powerful stimulant that can be smoked, eaten, snorted or injected. Individuals who use meth experience heightened wakefulness and a reduced need to sleep. Short-term effects include an increased heartbeat and high blood pressure. Long-term use can lead to confusion, mood swings, delusions, itching, and sores on the face and body.

Prescribed Medications
Individuals are increasingly using and misusing prescription medications. While these substances are prescribed by doctors and purchased in pharmacies, an increasing number of individuals are purchasing power prescription medications for non-therapeutic purposes. Commonly misused medications include opioids, like codeine and Oxycontin, stimulants, including Metadate and Ritalin, and depressants or sleeping pills, like Ambien and Xanax. Misusing these medications can lead to overdosing, an increase in heart problems, including heart attacks, and mental impairment.


Synthetic Marijuana (K2, Spice)
Synthetic marijuana is often referred to as spice. It is manufactured by spraying dried herbs with various chemicals that mimic the effects of THC. Synthetic marijuana is often much stronger than regular marijuana, and users typically smoke or eat the substance in order to achieve a high. Short-term effects include hallucinations, increased blood pressure, confusion, and vomiting. The long-term effects are not yet known.

Effects Of Illicit Substance Use

Illicit substances are drugs and chemicals that are commonly ingested for their side effects. Individuals who use and misuse illicit substances are typically trying to achieve a sense of euphoria or well-being, relief of mental and/or physical pain, increased energy, and/or an altered mental state.

Signs and Symptoms of Illicit Drug Use

Substance abuse disorder affects every aspect of an individual’s life, and individuals who have a family history of substance abuse, traumatic experiences or events, and mental disorders are at a higher risk of developing a drug dependency. During the experimental phase, signs and symptoms may be difficult to spot, but as the substance use turns into substance abuse disorder, you will notice changes in the individual’s behavior and appearance.

Some of those changes include:

  • Increasingly late to work, school, and social obligations
  • Frequent mood swings
  • Failing to maintain financial responsibilities, like paying rent and utility bills

Recovery and Treatment Options for Illicit Drug Abuse

If you suspect that you or a member of your family is suffering from substance abuse disorder or using an illicit substance, getting professional treatment from a drug treatment rehabilitation center can help. Rehabilitation centers offer inpatient and outpatient detox programs, drug education programs, and family and individual counseling and therapy to help individuals overcome substance use disorder. Many times a health insurance plan can help pay for the costs of treatment.