Dangers of Illicit Drugs, Their Effects and Treatment Options

Last Updated: May 16, 2024

Nena Messina Authored by Nena Messina, Ph.D.
Dr. Ash Bhatt Reviewed by Dr. Ash Bhatt
0 sources cited

Illicit drugs, such as marijuana, are any drugs that are illegal to either manufacture, distribute, or use. Drugs or substances that fall under this category might not be legally manufactured or sold, even as prescription medication, as no special licenses exist for this purpose. This also applies to illicit drug use. While in some cases prescription medication can be restricted for use only under medical supervision, illegal drugs cannot be administered in this way as they are illegal for use even by medical professionals.

In 2018, the prevalence rate of illicit drug use for 12 years old above in the United States is 11.7%. To define illicit drugs, various drug regulation and enforcement agencies, including the DEA, CDC, and FDA classify such drugs in a manner that prohibits and outlaws their manufacture, sale, or use. A person dealing with any drug thus classified should be aware that they are operating outside of the law and exposing themselves to the dangers of using illicit drugs.

In this article, information about the types of illegal drugs, effects and signs of illicit drugs addiction and abuse, illicit drug overdose, and how to treat illicit drug addiction will be provided.

What Are Illicit Drugs?

Licit drugs are substances that can, by law, be manufactured, distributed, and consumed. When a person walks into a drug store and buys some aspirin or Tylenol, it is because these drugs have not been classified as illegal drugs. So, what are illicit drugs, and why are drugs illegal, then? An illegal substance has been classified by law as illicit. In the US, this codification is sanctioned by The Controlled Substances Act, which establishes explicitly which drugs are to be considered illicit.

The law, abbreviated as CSA, categorizes all substances that were in some way controlled by existing federal laws into five Schedules. The law further provides for some mechanisms for controlling how various drugs are categorized by allowing them to be moved from one schedule to another. This provides a way of ensuring drugs are either properly classified within the five schedules or decontrolled. Decontrolled drugs are those that are no longer classified as restricted substances. All illicit drugs or illegal narcotics are in the V Schedule spectrum.

Types of Illegal Drugs

There are different types of illegal drugs and each of these substances is administered differently. Based on the report of the National Institute on Drug Abuse, there is an opioid crisis today and the most frequently abused types of drugs are opioids. Moreover, 4-6% of the people who misuse these opioids shift to heroin.

Some of the types of illegal drugs include:

  • Cocaine is a recreational drug with strong stimulant effects. The drug is classified as a Schedule II drug. When snorted, inhaled, or injected, the drug has the effect of increasing a person’s heart rate, causing sweating, and dilated pupils. Cocaine causes addiction by rewiring the reward pathways of the brain through the inhibition of the reuptake of serotonin, dopamine, and norepinephrine, making the person dependent even after short use.
  • Crack, also known as crack cocaine, is on the list of illegal drugs and it is a form of cocaine that can be smoked. Crack is found to be more addictive than cocaine owing to the quick and intense high it gives when smoked. The easy availability and affordability of crack have made it the bane of impoverished communities in the United States. A person who gets started on crack will often experience a rapidly escalating drug abuse problem with related issues such as crime following closely after.
  • Ecstasy – the colloquial term for 3,4-Methylenedioxymethamphetamine or MDMA in short, ecstasy is known as a party drug due to its close association with the party and rave culture. A person on MDMA will experience a heightened sense of empathy, sensuality, and euphoria after about an hour of taking the drug. While these effects can last for up to 6 hours, the drug comedown that follows is often characterized by feelings of depression and loneliness.
  • Hallucinogens are powerfully psychoactive substances that cause hallucinations, anomalies in perception, and other emotional, and consciousness changes. Hallucinogens fall into three categories; psychedelics, dissociatives, and deliriants. Substances that are termed hallucinogens include LSD, DMT, mescaline, and ayahuasca. The US Controlled Substances Act classifies most well-known hallucinogens as Schedule I substances.
  • Heroin is one of the opioids that is abused for its euphoric effects. There are some countries where heroin is used as a pain reliever, but in the United States, it is on the list of illegal drugs. It is classified under Schedule I drugs and it has a high likelihood of causing addiction in users resulting in side effects such as decreased breathing, infected heart valves, and even death.
  • Inhalants are a class of substances commonly found in manufactured products that are then sniffed or inhaled to induce a drug euphoria. These are industrial chemicals like gasoline and glue that are used in everyday products, but which are then abused in a manner not intended by the manufacturer. Sniffing inhalants is a deadly habit that can lead to death from hypoxia, cardiac arrest, or vomit aspiration. Brain damage is also associated with long-term use.
  • Ketamine, another substance on the list of illegal drugs, is abused for its depressive properties. A person getting high on ketamine will experience lethargy and slurred speech as well as an altered sense of reality once the drug begins to wear off. Frequently used as a pre-op anesthetic medication, the drug is favored for its ability to induce a trance-like state where the patient experiences pain relief, memory loss, and sedation.
  • Marijuana – is marijuana an illicit drug? According to the Drug Enforcement Agency, yes. The drug falls under Schedule I, the highest designation any drug can get. Derived from the cannabis plant, marijuana is a psychoactive drug that induces a sense of euphoria, highness, and altered perception when taken. People who smoke, vape, or ingest marijuana regularly are at risk of forming an addiction to the drug over time. Although it is also important to note that many states are now reviewing the potential harms of marijuana and emphasizing the positive aspects of its use for medical  purposes.
  • Meth – illicit drugs statistics place meth at the very top of highly addictive and destructive synthetic substances. Full name N-methylamphetamine, meth is a powerful CNS stimulant that is abused in both low and high quantities by persons looking to benefit from its effects. In small doses, it causes increased alertness, concentration, and a reduction in appetite that favors weight loss. At high doses, psychosis sets in followed by a breakdown in skeletal muscles, intracranial bleeding, seizures, and death.
  • Spice – is a slang term used to refer to synthetic cannabinoids. These chemicals mimic cannabis psychotropic agents by binding to the cannabinoid receptors in the body. They result in a cannabis-like high. Marketed as designer drugs, these substances are designed to provide a high while evading law enforcement because of the different chemical structures of the substance. As of 2012, spice and other synthetic compounds were banned by the signing into law of the Synthetic Drug Abuse Prevention Act of 2012.

Some may wonder, why are drugs illegal? To answer, just like when people abuse alcohol and tobacco, it is important for those who abuse these drugs to understand that health dangers await. Therefore, these drugs should be avoided at all times.

Effects of Illicit Drugs Addiction

Illicit drug abuse carries with it several side effects, as well as criminal prosecution, that affect the user both in the short term and long term. While the effects of illegal drugs are as broad as the types of substances that constitute the category, some general side effects cut across all illegal drugs. For a person with illegal drug addiction, understanding the possible side effects of using these substances can act as a deterrent to continuing taking them. For a person who may have once taken an illicit drug, these side effects can work as a warning sign to not go down that road again. In this section, information about the physical and mental effects of illicit drugs will be provided.

Physical Effects of Illicit Drugs Addiction

Based on the study of healthcare professionals from California, the use of all illegal drugs and substances like alcohol can lead to accidental injury. Consistent with the report from the University of Michigan, the leading cause of accidental death and injury is caused by substance abuse, followed by physical or sexual violence. These two are both present in adolescent and adult users.

Other physical effects of illicit drugs addiction include:

  • Premature menopausal and decreased reproductive capabilities. Sometimes, sexually transmitted diseases are also possible to occur. Aside from illegal drugs, people should be aware of the medications that can affect sexual health.
  • Respiratory problems such as asthma and lung infection. The most common symptom of lung problems due to illicit drug use is shortness of breath.
  • Heart diseases, ranging from hypertension to stroke or cardiac arrest. Take note that the use of illegal drugs causing heart problems is also related to alcohol and tobacco use.
  • Liver problems do not only happen because of alcohol use. Even illegal drug use can cause diabetes. When the use of illegal drugs is not halted, this could lead to irreversible liver damage.
  • Kidney problems may also arise when patients use illegal drugs. Aside from severe kidney damage, when patients continually use these substances, these substances could cause kidney failure, making the patients subject to lifetime dialysis.


Aside from these, cancers can also be experienced. Based on the report of researchers from Oregon, those who smoke marijuana are more at risk of lung cancer. For those with other substance use disorders like alcohol use, seeking help through Alcohol Anonymous meetings would be of great help.

Psychological Effects of Illicit Drugs Addiction

Aside from physical effects, there are also psychological ones. Based on the report of psychologists from Massachusetts, substance use disorder is one of the significant factors for suicidal ideation or behaviors.

Other mental effects of illicit drugs addiction include:

  • Mental confusion due to brain damage. As illicit drugs affect the brain, the brain structure changes, making the users vulnerable to emotional harm.
  • Problems with decision-making and inability to focus well.
  • Other mental disorders such as ADHD, conduct disorder, mood disorders, bipolar disorder, panic disorder, post-traumatic stress disorder, and anxiety disorders like social & specific phobias, and generalized anxiety disorder.
  • For older adults, dementia and insomnia may also occur.

Looking at these effects, it is safe to say that the use of illicit drugs comes with long-term effects that are detrimental to health. Patients who want to safely recover from illicit drug addiction might consider addiction treatment at rehabilitation centers.

Effects of Illicit Drugs Addiction

Illicit Drug Addiction And Abuse Overview

In the United States, illegal drug use affects 9.4% of the population, or approximately 24.6 million Americans aged 12 and above. These findings were published in a landmark survey conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA) titled the National Survey on Drug Use and Health (NSDUH) and held in 2013. The results showed that this number had increased from 8.3% in 2002. While the use of most illegal drugs remained constant, the use of marijuana spiked, possibly leading to an increase in the overall number of illicit substance users.

In another report from the Substance Abuse and Mental Health Services Administration (SAMHSA), in 2017, 38% of adults in the United States battled an illicit drug use disorder, and 1 out of 8 of these battled between alcohol and drug use. Based on the 2019 World Drug Report, 35 million people worldwide suffer from drug use disorders, and only 1 per 7 people get treated. In this section, information about the signs and symptoms of illicit substance abuse and who is most at risk of this addiction will be provided.

Signs and Symptoms of Illicit Substances Abuse

Before an illegal drug addiction becomes full-blown, several telltale signs point toward the problem. If a person is using illicit drugs, an observant person can be able to identify the symptoms of illegal drug addiction and initiate an intervention. For persons using the substances recreationally, looking for illicit drug use signs in themselves can prevent the escalation of the habit into a stubborn addiction that will take a lot of effort to overcome.

Physical Signs of Illicit Drugs Abuse

There are early physical signs of illicit drug abuse. According to a study published in the Innovations in Clinical Neuroscience, the most common one is withdrawal from usual family bondings, routines, and activities.

Other physician signs of illicit drug abuse include:

  • Tolerance And Dependence: Tolerance sets in when the body needs increasingly higher doses of a substance to get the same experience whereas dependence is a state of relying on a drug to get through the day.
  • Weight Loss: A drug user will over time lose weight as they neglect their health and wellbeing.
  • Eye Changes: Bloodshot eyes, constricted or overly dilated pupils, or sleepy eyes.
  • Changes in sleep patterns: Insomnia (difficulty sleeping at night) or hypersomnia (sleeping for too long).
  • Skin complexion changes: Appearance of acne, paleness, jaundice, scabs, scars, bruises, and track marks on the body.
  • Paying no attention to personal hygiene: Not bathing regularly, not brushing teeth, and decreased physical cleanliness. Usually, if not tooth loss, the teeth of people with substance abuse disorders become decayed.

Sometimes, difficulties in verbal expressions such as slurring of speech can also be observed. Although some users become aloof, others become more talkative. If the behavior of the alleged user starts to change, it is highly recommended to seek medical help from medical doctors, rehab centers, and even psychologists.

Psychological Signs of Illicit Drugs Abuse

Aside from the physical signs, there are also psychological signs of illicit drug abuse. Based on the study of a psychologist from California, the most common psychological sign of illicit drug use includes changes in behavior and mannerism.

These changes include the following:

  • Violent behaviors: Caustic reactions, uncharacteristically defiant, stealing money and things, and destroying of properties.
  • Personality Changes: A person on illegal drugs might be chirpy and outgoing at one time but then descend into a dark and somber mood at another. These extreme personality changes can be a sign of drug abuse.
  • Lack of Motivation or Initiative: Whether it’s getting up in the morning to go to work or school, or getting an assignment done, a person on illicit drugs will struggle to get even the simplest tasks done.
  • Negative Emotions: When addiction is full-blown, a person will experience dark and depressing thoughts. These will be conveyed as negative emotions like lashing out at people, being overly critical of others, and reacting poorly in all manner of situations.
  • Mood Swings: A drug user might at one time be smiling and at the next cursing one out. Because they have fallen into the clutches of addiction, such a person is rarely in control of their moods.

Based on one research from the University of Maryland, poor morale and violation of curfew restrictions are also early signs of teens with substance abuse disorders. Parents or those who see these physical changes should seek medical help as soon as possible to avoid unwanted health events.

Who Is Most At Risk Of Illicit Drug Addiction And Abuse

Based on the different statistics mentioned above, patients 12 years old and above are most at risk of illicit drug addiction and abuse. Consistent with the report from the National Institute on Drug Abuse, the addiction to these substances is widespread. In another report published in the Archives of Pediatrics & Adolescent Medicine, teens, as early as 6th to 8th grade, are getting involved in illicit drug use. Additionally, family, peer, and work settings are related to this substance abuse.

Illicit Drug Overdose And Dangers Of Withdrawal

The prevalence of illicit substance overdose is around 128,000 per year and 69% of these patients are below 50 years old, and in 2018, it was reported that 2 out of 3 overdose cases involve the use of opioids. Additionally, in a clinical review from the United Kingdom, those who inject these illicit drugs are most at risk of overdose. 

Some of the signs and symptoms of illicit drug overdose include the following:

  • Dilated pupils
  • Shallow breathing
  • Weak, or thready pulse
  • Cold, clammy skin
  • Unconsciousness and coma
  • Blue-tinged skin
  • Chest pain
  • Stomach upset
  • Confusion
  • Headaches

Always remember that overdose is life-threatening. Anyone who is seen with these signs and symptoms should be admitted to medical services. 

While waiting for the response of 911 or national poison centers, one person should never leave the patient unattended and may do the following:

  • Always place the patient to their side to prevent asphyxiation
  • If the patient is cautious, do not give any drinks or food as this might alter the levels of the drug taken
  • Try to find out what drug the patient has overdosed on

Apart from an overdose, withdrawal is also possible with illicit drugs. When patients stop the use of these substances and their bodies can no longer feel the effects, dangerous withdrawal symptoms ranging from flu-like symptoms to heart complications can be experienced. With the help of specialists from rehab centers, proper detoxification, using detox medications or detox drinks, from these substances will be given.

Illicit Drug Overdose

Illicit Drug Addiction Treatment and Rehab

Having an illicit drug addiction is not the end of the line. Today, effective illicit drugs addiction treatment options exist that can help a person quit the addiction and return to normal life. Treatment, however, only starts when a person admits to themselves that they have a problem. This first step is what makes the difference between those on the road to recovery and those still stuck in addiction. Once a person admits to this, they can then take the next step, which is to seek out appropriate illicit drug use treatment, which comes in one of two structures, inpatient vs outpatient rehab.

  • Inpatient Rehab – When a person chooses an inpatient rehab, they get the option to stay for as long as they need to as well as the option of enrolling in a program far away from where they live. The downside to inpatient rehab centers is that they can act as a bubble and create a false sense of safety for the addict. That is why an inpatient rehab program must be followed up with an outpatient recovery program.
  • Outpatient rehab – is frequently used to treat mild to moderately severe cases of drug addiction. When a person enrolls in an outpatient rehab program, they commit to attend the sessions regularly and to take whatever medication is prescribed. This needs the person to be committed and focused on kicking the addiction.

Overcoming an illicit drug habit is possible. While illegal drugs are everywhere and the war on drugs is still ongoing, individuals must take responsibility for their protection against the vagaries of these substances. Understanding the devastating effects of these substances can help a person not only avoid them but also caution others of the same.

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Page Sources

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Published on: April 11th, 2018

Updated on: May 16th, 2024


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