5 Of The Most-used Illicit Drugs & Their Effects

The mind-altering, chemical substances to which an individual can develop a dependency are numerous and diverse. Ranging from the more natural and herbal to the synthetic and chemical, drugs are known to produce a variety of physiological effects, but more often than not individuals abuse drugs for the purpose of becoming intoxicated. However, the thrill and euphoria associated with intoxication quickly overshadow the fear individuals have the adverse effects of these drugs, leading to more frequent abuse of drugs and the development of chemical dependency. In short, experimentation with dangerous substances can quickly lead to addiction.

While there are numerous substances found to be abused, some drugs are more commonly abused than others. The following are five of the most commonly used illicit drugs and the effects that make them so dangerous and addictive.


Although marijuana would technically be the third-most commonly abused substance behind alcohol and tobacco, marijuana remains illegal according to federal law as well as in most states and, therefore, would be considered the most commonly abused illicit drug. Marijuana is frequently characterized as being the “gateway drug” due to the tendency for youths who experiment with cannabis to be significantly more likely to experiment with other types of drugs. However, recent research has found that marijuana’s characterization as the quintessential gateway drug may reflect both a behavioral element as well as a biological or neurological element; in particular, individuals who experiment with marijuana during adolescence have been found to have decreased reactivity to dopamine and other neurochemicals in the brain’s reward pathways, which means that they’ll be more likely to develop a quick dependency on substances that cause a surge in dopamine levels such as marijuana and other drugs.

Marijuana is derived from the hemp plant known as Cannabis sativa, which its active ingredient tetrahydrocannabinol, or THC, to which is attributed the majority of the drug’s effects. When an individual consumes marijuana—most commonly by smoking the plant, but it’s not uncommon for individuals to eat baked goods or other prepared foods to which marijuana is added as an ingredient—they become high, which is triggered upon the body’s rapid absorption of the drug’s THC.

In terms of the physical effects of marijuana, individuals often experience an increase in heart rate that has been known to occasionally result in heart attacks shortly upon intake; however, others have experienced a decrease in blood pressure and a number of effects to the lungs due to consistent smoking. The high that individuals experience while under the influence of marijuana frequently includes dizziness and lightheadedness, an increase in appetite, significantly slowed reaction time, shallow breathing, sleepiness, and dry mouth. Though not widely known for being highly addictive, individuals can develop a physiological dependence on marijuana and experience irritability, insomnia, loss of appetite, inability to concentrate, and other effects when they go a period of time without consuming marijuana.

Opiate Painkillers

Until relatively recently, prescription painkillers, or opioids, had accrued one of the highest rates of addiction relative to other drugs and had been a major public concern. Individuals who suffered from health conditions involving chronic pain were frequently prescribed these medications by physicians who hoped to help them achieve better quality of life; however, the resulted in a number of individuals developing a dependence on those substances. Moreover, opiates quickly developed a reputation for packing so much power in a small form, making them incredibly valuable on the street. In a relatively short period of time, more and more individuals were becoming dependent on opiate painkillers, which also started to become harder for individuals to obtain. A number of federal regulations made it more difficult for individuals—even those who needed the drugs for legitimate conditions—to obtain prescriptions for opiates from doctors, which also resulted in a diminishing supply of opiates sold on the street.

There are many opiate painkillers that have been prescribed and are prescribed today with the most well-known ones including hydrocodone, oxycodone, morphine, hydromorphone, and fentanyl. When individuals consume an opiate or narcotic painkiller, the initial effects are essentially those of a depressant; one’s heart rate and blood pressure decrease, breathing slows, and individuals become drowsy. However, the most important effect of opiates is the one for which they’re actually designed and intended, which is to substantially decrease sensitivity and perceptions of pain. Some of the adverse effects that are sometimes experienced include constipation, severe drowsiness, nausea and/or vomiting, and a loss of appetite.


Similar to opiate painkillers, benzodiazepines—diazepam, alprazolam, lorazepam, clonazepam, and others—act as depressants on the body’s central nervous system and are most frequently prescribed or used as sedatives. As such, benzodiazepines are common for the treatment of conditions that involve stress and anxiety, tension, sleep disorders, epilepsy and seizures, and a number of other mental or emotional symptoms. Benzodiazepines are even frequently given to individuals in treatment for addiction, especially during detoxification as a means to alleviate withdrawal symptoms. Some of the effects of benzodiazepines that have been reported include the feeling of having a “hangover” and being excessively drowsy the next day, unusual sleep habits such as talking in one’s sleep, decrease in memory and cognition with heavy long-term use, blurred or double vision, and nausea or vomiting.


One of the higher-priced substances that’s been referred to as the “caviar of street drugs,” cocaine is much different from those substances mentioned above in, among others, one very important way. Rather than being a depressant that slows bodily processes, cocaine is a powerful stimulant, causing a significant increase in heart rate and blood pressure. Most often consumed by insufflating, or snorting, cocaine in powdered form, the onset of the drug’s high tends to be very quick, taking only a couple of minutes and lasting between fifteen minutes and an hour. Cocaine’s high has a marked effect on one’s brain, emotions, and heart, causing strong feelings of euphoria, a rush of energy, feelings of alertness, and oftentimes even feelings of supremacy or invincibility. Users of cocaine often exhibit very large, dilated pupils, restlessness and lots of anxious energy, exuberant or fast-paced speech, and are often quick to become irritated or aggravated. Some of the more dangerous effects of cocaine include the potential for a heart attack or to go into cardiac arrest due to the drug’s stimulating effects, constricted blood vessels in the brain that can lead to stroke, stomach ulcers, and even kidney failure.


After the federal changes that made it more difficult for individuals to obtain opiate painkillers, an alarming number of individuals switched to heroin in order to maintain their addictions with a cheaper substance that is widely available and produces virtually the same effects. Heroin and opiate painkillers both fall under the blanket category called opioids, which are substances either molecularly similar to or derived from the opium obtained from the opium poppy. Heroin is arguably the most dangerous opioid of all being that it’s the most powerful and also unregulated, which means that the heroin individuals are buying on the streets can range from being incredibly pure and powerful to being very weak due to adulterants added to it.

Most often injected directly into the bloodstream using a hypodermic syringe, heroin is another depressant that also decreases perceptions of and sensitivity to pain. When an individual imbibes heroin, he or she feels what is often referred to as a “rush” consisting of happiness, the sensation of warmth and tingles throughout the body, and the perception that the world has slowed down. Many heroin users have compared the high they get from heroin to being “covered in a warm blanket,” which also emphasizes the buffer the drug places between the individual and tactile sensations. In other words, heroin causes a sort of physical and psychological numbness. However, as a depressant, heroin slows down the body and its internal processes, which includes slowing one’s heart rate and being a strong respiratory depressant. In fact, individuals who die due to a heroin overdose are often found to have simply stopped breathing due to the high level of heroin in their bodies.

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