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Dangers of Illicit Drugs, Their Effects and Treatment Options

Last Updated: February 23, 2021

Authored by Nena Messina, Ph.D.

Illicit drugs are any drugs that are illegal to either manufacture, distribute or use. Drugs 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.
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.

What are Illicit Drugs?

Licit vs. Illicit Drugs

Illicit drugs have hidden dangers and can cause addiction
Licit drugs are drugs that can, by law, be manufactured, distributed and consumed. When a person walks into a drug store and buys some aspirin or Tylenol, it’s because these drugs have not been classified as illegal drugs. On the other hand, an illicit 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 as 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 of 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 a restricted substance. All illegal drugs exist somewhere in the 5-schedule spectrum.

Illicit Drug Scheduling

Schedule I

These are illicit drugs and substances that are extremely likely to be abused. They also have no currently accepted medical uses and do not have a safe way of use or administration. Illicit drugs in this category include GHB, LSD, and heroin.

Schedule II

These also have a high likelihood of abuse and can lead to severe physical and psychological problems. Although they do have accepted medical uses, they come with strict guidelines. Illicit drugs in this category include morphine, cocaine, methadone, and phencyclidine (PCP.)

Schedule III

Illicit drugs in this schedule carry a lesser likelihood of abuse and have accepted medical uses in the United States. Abuse leads to low to moderate physical and psychological dependence. Drugs in this category include anabolic steroids, aspirin, and Tylenol.

Schedule IV

They have a low potential for abuse and have current medical uses in the United States. Abuse might lead to mild dependence without any serious side effects. Diazepam and clonazepam are examples.

Schedule V

Relative to illegal drugs in the other schedules, these have a low likelihood of abuse. They also have accepted medical uses in the US and can lead to mild dependence if abused. Cough medicines are an example of illicit drugs on this schedule.

Illicit Drug Abuse Statistics

Before looking at some statistics, let’s first answer the question, what is illicit drug use? By definition illegal drug use is the use of restricted and outlawed substances. 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 the increase in the overall number of illicit drug users. While this drug-spiked, another illicit drug, cocaine, went down by close to a million users. This was occasioned, however, by the rise in synthetic illicit drugs such as methamphetamines, which are easier to manufacture. In reflecting this, the survey saw a concomitant spike in meth use, with 595,000 people using the substance in 2013 compared to 353,000 in 2010. The study also found that illegal drug abuse peaks in the young demographic aged late teens and twenties.

Illicit Drugs and Society

In the US, the war on illicit drugs is an entrenched effort by consecutive administrations to stop the production, distribution, and use of illegal drugs. Starting in the 1800s, opium became popular immediately after the American Civil War while the 1880s saw the rise of cocaine. To stem this tide, the Harrison Narcotics Act was enacted in 1914 and became the United States’ inaugural federal drug policy. All these came to a head with the official kickoff of the war on drugs by President Richard Nixon in 1971 and the subsequent formation of the Drug Enforcement Agency.
Despite these efforts, drug abuse is still alive and rampant in the US. Efforts to sensitize the public on the ills of illicit drugs possibly will bear fruit as this would go towards depressing demand, a critical factor in dismantling supply networks. For persons abusing illicit drugs, finding treatment and starting an individualized path to recovery is the right approach. While society will take time to evolve illegal drugs off the streets, every person must remain vigilant to protect themselves from getting hooked on these poisonous substances.

What are the Types of Illegal Drugs?

Different types of Illegal DrugsCocaine 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 reuptake of serotonin, dopamine, and norepinephrine, making the person dependent even after short use.
Crack, also known as crack cocaine, is a form of cocaine that can be smoked. Crack has been 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.

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 as hallucinogens include LSD, DMT, mescaline, and ayahuasca. The US Controlled Substances Act classifies most well-known hallucinogens as Schedule I substances.
Going by the street names of dope, smack, horse, brown, among others, heroin is an opioid substance 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 illicit drugs list.

Inhalants are a class of substances commonly found in manufactured products that are then sniffed or inhaled to induce a drug high. These are industrial chemicals like gasoline and acetone 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 is one of the types of illicit drugs that is abused for its depressive properties. A person taking 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.
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.

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. At 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.
One of the more attractive names of illegal drugs, 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 structure of the substance.

The Signs and Symptoms of Illicit Substances Use

Before an illegal drug addiction becomes full-blown, several telltale signs point towards 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 drugs use signs in themselves can prevent the escalation of the habit into a stubborn addiction that will take a lot of effort to overcome.

Behavioral Signs of Illicit Drugs Use

Poor Judgement: Persons with an illicit drug habit will often make judgment calls that favor the addiction rather than logic. For instance, a person will choose friends who enable the addiction, something that works against them by worsening the problem.
Drug-seeking Tendencies: A person addicted to illicit substances will go to great lengths to obtain the next fix. These great lengths might include traveling to dangerous neighborhoods where accessibility to illegal drugs is easier or engaging in criminal behavior to get drugs.
Financial Challenges: In many cases, a drug addict will spend all their money on illicit drugs. This happens because they need larger quantities of the drug, which consequently cost more to purchase. As a result, a drug addict could eventually lose their job, get evicted from their house and end up living in poverty.
Irresponsibility: A person on illicit drugs will be mostly irrational and irresponsible. Such a person will take unwarranted risks to either get drugs or use up the high they are on. The person will also forsake their responsibilities including parenting, schooling and/or a job.

Physical Signs of Illicit Drugs Use

Tolerance: Tolerance sets in when the body needs increasingly higher doses of a substance to get the same experience. Someone using illegal drugs will develop a greater appetite for over time. Seeing this in a person is a sure sign of addiction.
Dependence: Dependence is a state of relying on a drug to get through the day. Dependence exhibits itself as an overly enhanced need for illicit drugs to function properly. A person with such a dependence will act almost normal when on illegal drugs but fall apart when the drug wears off.
Weight Loss: A drug user will over time lose weight as they neglect their health and wellbeing. As illicit drugs consume the person’s faculties, a person on them will only think about the next fix and the next high. They will also use all their money on illegal drugs rather than on their basic sustenance.
Eye Changes: Bloodshot eyes, constricted or overly dilated pupils, or sleepy eyes all point to drug use, especially if these changes happen suddenly. A person on illicit drugs will seldom be clear-eyed, neither before nor after taking them.

Psychological Signs of Illicit Drugs Use

Personality Changes: Illicit drugs cause extreme personality changes that are easily noticeable by an observant person. 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. This lack of motivation can be a sign they are operating on illicit drugs to get things done.
Negative Emotions: When an 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. Their moods are ever dictated by the state they are in, whether high or experiencing a debilitating comedown.

What are the Side Effects of Illegal Drugs Abuse?

Woman in coma at hospital because of illicit drugs abuse
Illicit drug abuse carries with it several side effects 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, there are some general side effects that 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.

Short-term Side Effects of Illegal Drugs

Decreased breathing: Most illicit substances act on the Central Nervous System, the center involved in the regulation of vital functions such as breathing. When a person takes an illicit drug, their breathing might become depressed and this could lead to hypoxia (oxygen deprivation) and further to more serious complications.
Impaired judgment: When a person is high on illicit drugs, they may not be able to make sound decisions. This can lead to risky behavior such as having sex with multiple partners with no protection, driving under the influence, or getting into criminal acts. When a person takes illegal drugs, they expose themselves to such situations to deadly effect.
Poor coordination: Another short-term side effect that cuts across most illicit substances, poor hand-eye coordination can be dangerous. If a person on illicit drugs is operating machinery, for instance, this lack of coordination might lead to an accident. Poor coordination can also lead to injurious falls and other similar accidents.
Inattention: While some illegal drugs increase attention, once a person gets addicted, the effect is almost always the contrary. As the person is now constantly seeking the next high, their ability to focus on anything dwindles. They may also get restless, which will also affect their ability to pay attention.
Increased heart rate: If the illicit drug taken is a stimulant, this will raise the heart rate. An example is cocaine, which quickly raises the heart rate when taken. While this might not be fatal under normal circumstances, if a person has a heart defect, this could trigger a heart attack.
Coma: If a person overdoses, the result could be a coma. Comas often happen to drug addicts and can last for anything from a few hours to weeks. This happens because most addicts at some point are unable to control their drug intake, leading to consumption of dangerously high doses that ultimately lead to a coma.

Long-term Side Effects of Illegal Drugs

Addiction: Continued use of an illicit drug leads to tolerance, then dependence, then addiction. An addict is a described as a person who functions at the mercy of illicit drugs. Such a person has no life and spends their every waking moment either getting high or looking for the next high. This long-term effect can destroy a person’s life and livelihood.
Brain damage: Substances with psychoactive properties cross the blood-brain barrier and impact the brain. When this happens consistently, neurotoxicity occurs which ultimately leads to cell necrosis. Brain damage arising in this manner is permanent and can lead to more complications such as memory loss, permanent loss of coordination, among others.
Malnutrition: As a person entrapped in a drug addiction focuses on drug seeking actions, neglect of basic needs tends to occur. Such a person will not have nutritious meals, and this will lead to malnutrition. Over time, this will lead to a depressed immune system and expose the person to opportunistic diseases such as TB and HIV.
Suicidal thoughts: When a person finds themselves addicted to illicit substances, they could lose hope. At this point, suicidal thoughts and ideation might creep in as they try to escape the maze they are in. These thoughts become more pronounced over time as the addiction gets worse. Getting timely help for the addiction can help prevent these thoughts from escalating.
Chronic insomnia: As most psychoactive illicit drugs affect the CNS, which also regulates sleep, prolonged use can rewire these pathways and render the sleep hormone, melatonin, useless. Chronic insomnia that results can prove to be resistant to mild sleep medication and lead the person to take stronger sleeping pills, which in themselves also represent a danger to the person.
Death: Over time, illicit drug use can lead to death. This could happen as a drug overdose, or because of the combination of all these side effects that culminate in a fatal outcome. Quitting illegal drugs early is, therefore, a life and death situation that any person taking them should consider.

Illicit Medications Addiction Treatment and Rehab

Addiction Treatment Options

Seeking illicit drug treatment is the path to a new lifeHaving 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 rehab, and outpatient rehab.

Inpatient Rehab

A person struggling with a severe addiction will benefit most from an inpatient illicit drugs rehab. As the person may be free-falling and require structure and a controlled environment to begin detox, a residential facility would be more effective. 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.
When at the rehab center, the person will be able to relearn what it means to be drug-free. They will have the opportunity to build positive relationships with those around them and engage in activities that take their mind of illicit drugs. 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

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 on a regular basis and to take whatever medication is prescribed. This needs the person to be committed and focused on kicking the addiction. For an outpatient rehab program to be successful, the person will need a lot of moral and social support from friends and family to encourage them to stay the course and complete their rehab. Such patients tend to transition smoothly to an outpatient recovery program as they often already have the support networks they need to keep moving in the right direction.

Steps to Recovery


When a person decides it is time to act and join a rehab facility, the first step they will have to undertake is the intake process. During this process, they will have an opportunity to ask questions regarding the rehab programs offered, costs, and payment options. The rehab center will also interview the person to find out what their needs are and whether the programs on hand fit those needs. Before signing up for the rehab, all details must be clear to the person joining as starting to switch gears midway through the program could interfere with the rehabilitation process. Once all necessary intake issues have been sorted out, the person will then move to the detoxification stage.


Detoxification is the process of weaning the body from the substances it was used to getting. Withdrawal symptoms will rear their ugly head during this process. Fortunately, modern medicine has created substances that reduce these withdrawal symptoms and make them more bearable. Depending on the illicit drug, the rehab center will administer certain drugs to interfere with how the body uses or craves for illicit drugs. These drugs are either agonists such as methadone and buprenorphine that compete with illicit drugs to bind to receptors, or antagonists such as Naltrexone and Naloxone, that prevent illicit drugs from binding to receptors.


On successful detoxification, a person now enters a period of rehabilitation. Rehabilitation combines medication-based therapy with behavioral therapies in a two-pronged approach targeted at preventing relapse. As at this point relapse is a clear and present danger, the person undergoing treatment may opt to extend their stay at the rehab center for the duration of this process. If the person has a strong support network, they may choose to go through rehabilitation on an outpatient basis. The anticipated outcome of rehab is to get the person to not only quit taking illicit drugs but to develop a different mindset about them altogether.

Recovery (Ongoing)

For most people, the process of recovery is a lifelong process. While they may complete all their sessions and finish their course of medication, recovery is a step they will have to undertake on a day by day basis. Before completing the program, the person will meet with counselors to discuss a recovery program. This could mean setting up family therapy structures that are ongoing. It could also mean joining a drug recovery group in the area. Other options worth considering during the recovery period include living in a drug-free facility with other recoverers, frequent testing for accountability or initiating ongoing post-rehab therapy sessions.

Overcoming an Illicit Drug Habit

Freedom from illicit drug addiction is possibleOvercoming an illicit drug habit is possible. If a person finds themselves with such an addiction, they must not lose hope. While the addiction does pose a challenge, finding help is the right step to take towards regaining control. 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. What matters most in beating an addiction is having the will and support structures to take the first step towards freedom.

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Published on: April 11th, 2018

Updated on: February 23rd, 2021

About Author

Nena Messina, Ph.D.

Nena Messina is a specialist in drug-related domestic violence. She devoted her life to the study of the connection between crime, mental health, and substance abuse. Apart from her work as management at addiction center, Nena regularly takes part in the educational program as a lecturer.


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