The 10 Most Common Illegal Types of Drugs

The illegal drugs are drugs that have restrictions of use or ownership by the government, and are illegal in certain situations. Countries have different laws about different drugs and there are also international treatments. However, the most common drugs in society are legal.

Surprisingly, most drugs were not created for playful purposes as they are currently used. On the contrary, its effects were discovered almost accidentally.

With the aim of finding increasingly better medicines, scientists have observed throughout history how certain substances act in animals and humans. Many of these substances were commercialized due to their beneficial effects.

However, over time it was common to discover hidden symptoms that could be dangerous or cause dependence. At the same time, healthy people began to abuse some of these substances for the pleasure or relaxation they felt, ignoring their risks.

Most Common Illegal Drugs

For this reason, these substances are currently outlawed. Nonetheless, drug use continues to be an important public health problem that even legal limits have not managed to solve.


The illegal substances most consumed today

1. Marijuana

Marijuana is the illegal drug most consumed. However, in some countries it is beginning to be legalized either for recreational use or for therapeutic purposes.

Normally it is considered a soft drug since it seems that it does not produce physical or chemical dependence, although it does have psychological addiction. On the other hand, it is known that it can produce changes in the central nervous system in some cases.

Marijuana consists of leaves, flowers, stems and dried seeds of the hemp plant, called Cannabis sativa. This plant contains a chemical called THC (tetrahydrocannabinol), the active principle of cannabis, which is the one that produces the effects.

You can consume pure smoked or mixed with tobacco in cigarettes or pipes. Although it can also be ingested by mixing with food (in a sponge cake, biscuits or infusions).

When this substance is smoked, THC travels rapidly from the lungs to the bloodstream. Through the blood, this chemical reaches the brain and other organs.

The brain already has natural THC receptors, but to receive so much of this substance produces a hyperactivation of brain areas that have more receptors of this type.

This causes symptoms such as altered sense of time, changes in mood (such as euphoria and easy laughter), relaxation, decreased pain, memory deterioration , difficulty solving problems, distortion of the senses (such as increased sensitivity), lack of motor coordination, etc.

Its prolonged use can have negative consequences especially if it begins to consume during adolescence. For example, in this case deterioration of cognitive functions such as memory, learning and reasoning occurs. A decrease in IQ scores has also been found (Johnston et al., 2015).

Other problems derived are respiratory disorders, mental illnesses (such as schizophrenia or anxiety) in prone people, increased suicidal thoughts, amotivational syndrome, lower performance and satisfaction with life, etc.


Another way to get THC is through the resin of the m@rijuana plant. This form of presentation is known as hashish, and it is a dark brown paste that can be very adulterated.

Its effects are similar to those of m@rijuana, although it seems to be more addictive and more harmful than it being adulterated with other substances.

2. Cocaine

The cocaine  highly addictive stimulant drug that comes from the leaves of the coca plant ( Erythroxylum coca ). It is illegal to grow it, process it, sell it or consume it. Although it has a limited and controlled use as an anesthetic for some types of surgery.

It consists of a white powder that is normally inhaled through the nose, although it can also be injected if it is dissolved first.

Cocaine acts by altering brain dopamine levels, specifically in the mesolimbic reward pathway. This means that it simulates the feeling of euphoria we have when we get a very valuable reward, even accentuates it.

The symptoms that the consumer has when he is under his effects is euphoria, sense of security and strength, disinhibition, increased heart rate, sleep disturbance and anxiety.

Often, after consuming cocaine, people may feel irritable, violent, hostile and paranoid. Once the effects diminish or disappear, the opposite reaction arises: depression, apathy and the need to consume more.

In the long term, it produces important consequences such as destruction of the nasal tissues (if inhaled), damage to the kidneys, lungs and liver; deterioration in the circulatory system, hallucinations, sexual dysfunctions, infertility, dental damage, irritability, delusions, depression, and even psychosis or schizophrenia.


Inside the cocaine, crack is found. It is a derivative of this, it has a much lower cost; and consists of a mixture of cocaine-free base with baking soda.

Cocaine base paste

It is often confused with cocaine base paste (bazuco or paco), the excess residue of cocaine that is usually processed with kerosene and sulfuric acid. They usually mix it with ether, chloroform and other substances.

These last two derivatives smoke and produce effects similar to cocaine, but much less lasting and generates more serious complications.


Also known as “eme” or “ecstasy”, it is a synthetic drug whose boom began in the 70s and 80s. It was gradually outlawed in almost every country in the world due to its dangers and health consequences, since it can lead to death.

It is mainly consumed orally by pills, tablets or powder. It produces alterations in the nervous system, increasing the amount of serotonin available in the brain.

The effect usually appears around an hour after being ingested, and consists of: euphoria, well-being, disinhibition, connection and intimacy with others, dilation of the pupils, increase in body temperature, decreased sleep, muscle tension and bruxism. 

However, this substance has a series of effects that can last up to a week after having consumed it. For example: irritability, depressive symptoms, impulsivity, anxiety, memory problems, anhedonia (inability to feel pleasure), lack of sleep, etc.

If used for a long time, it has been linked to brain damage, since the excessive increase in serotonin can be neurotoxic (causing imbalances and injuries to the nervous system).

4. Amphetamines or Speed

They are very addictive synthetic drugs, stimulants of the central nervous system.

It was synthesized for the first time in 1887, although medical experimentation with this substance emerged in the 1920s.

At the beginning the military used to overcome fatigue and increase alertness. Later, in the 40s and 50s, it was used for a variety of medical conditions such as ADHD, obesity, depression, etc.

In fact, it can still be obtained under a doctor’s prescription legally. Outside of the medical prescription it is illegal to consume it since it has many complications and causes addiction.

Currently it is used for therapeutic purposes (legally), or illegally for recreational purposes or sports performance increase.

Mainly consumed orally, rubbed on the gums or inhaled through the nose.

This substance works by promoting the release of dopamine and noradrenaline in the brain, neurotransmitters that produce pleasurable effects.

The symptoms of amphetamines are: euphoria, disinhibition, activation, increased concentration, improved memory, feeling of self-control, resistance to fatigue and regulation of appetite.

Its abuse can cause amphetamine psychosis, which arises from mental exhaustion. The person who suffers often have persecutory delusions, that is, believe that others go against him or what they do is to hurt him. It can be accompanied by depression, hallucinations and irritability.

5. Heroine

Heroin is one of the most potent drugs, since it causes great physical and psychological dependence in a short time. It is an @nalgesic that is derived from the plant “poppy”, and works as a depressant of the central nervous system.

It was synthesized for the first time at the end of the 19th century, with the aim of creating a substitute for morphine that treated pain, but without causing so much addiction.

From the 60s to the 90s their consumption rose alarmingly, causing the death of thousands of young people. It was considered a serious epidemic. When contemplating its dangerous consequences, its manufacture, possession and sale became illegal.

Due to the thought of rejection that has been generated in the following generations of this drug, its consumption has decreased significantly since then.

Its presentation consists of a white powder containing adulterants. Normally it is dissolved and administered intravenously, although it can also be inhaled.

The effects it produces are: immense pleasure, euphoria, lack of perception of pain, and strong sedation. These effects disappear progressively at 2 or 3 hours.

Once the person is addicted, it produces malnutrition, weight loss, digestive problems, constipation, anemia, lack of interest, depression, attention disorders, insomnia, alteration of menstrual cycles, etc.

6. Phencyclidine or PCP

Also known as “angel dust”, this drug emerged in the 50s and was used as an anesthetic. However, it stopped being used because of its side effects, such as delirium and confusion. It is currently an illegal substance.

It is a white crystalline powder that dissolves in water or alcohol. Although other pollutants are often added to expand and sell illegally, so it can take a brown tone.

It can be taken orally or inhaled. It affects various brain areas and different receptors. It is known, for example, that it works as an antagonist of the NMDA receptors in the brain producing the symptoms.

It is considered a hallucinogenic drug because it produces hallucinations; and dissociative, for causing disorientation and loss of the sense of identity.

The person may feel that he is isolated from the environment, disconnected from himself, and with a sense of unreality. It can also present a feeling of strength, amnesia, numbness of the extremities, difficulty speaking, lack of coordination, rapid eye movements and exaggerated gait.

In some consumers, it may have negative effects such as anxiety, a feeling of dying, paranoia, hostility, or psychosis. In addition, if the doses are very high it can cause seizures, coma or death (due to accidental injuries or suicides).

7. LSD

Or lysergic acid diethylamide, is a semisynthetic psychedelic drug that is characterized by its hallucinogenic effects.

At first it had a psychiatric use, but in the 60 the young people belonging to the counterculture began to use it recreationally. Therefore, it is currently an illegal drug, although in some cultures it has spiritual and religious connotations.

It is ingested orally, and its presentation is usually liquid (in drops) or impregnated with blotting paper, gelatin or sugar cubes. It takes effect approximately after a half hour of ingestion and these can last up to 12 hours.

Its main effects are hallucinations and perceptive illusions, synesthesia  (hearing colors, seeing sounds …), distortions of feelings, alterations of consciousness, experiencing a critical state of understanding of the world and of oneself, etc.

It has been shown that this drug does not produce physical dependence and is not toxic consumed very occasionally. Although in certain cases can cause delusions, paranoia and anxiety.

8. Ketamine

In its beginnings it was used as a general anesthetic for veterinary use, although it was also used in children and the elderly.

However, it was found that a small dose of this drug produced dissociative and hallucinogenic experiences. Currently its use is increasingly restricted in some countries, being exclusively for veterinary use or under medical prescription.

Normally its presentation is powder, and it is snorted or swallowed; although it can also be liquid, to be injected intramuscularly.

It acts in the human brain functioning as an antagonist of NMDA receptors, and at high doses, it binds to opioid and muscarinic receptors.

It results in a variety of symptoms that remain for about two hours. As sedation, floating sensation, numbness of the extremities, amnesia, lack of pain perception … As well as hallucinations and elevation of blood pressure.

On the other hand, it generates a feeling of being close to death, making the person feel that he is leaving his body. This is called “hole K”.

Its chronic consumption can produce severe depression, strong anxiety, memory problems and cognitive deterioration.

9. Popper

It is a liquid chemical called amyl nitrite. It was discovered in 1852 and was intended to be used for medical purposes, since it is a potent vasodilator. It also seemed to be useful to treat cyanide poisoning.

However, in the 70s it began to be consumed for recreational purposes, becoming very popular among h0m0sexual men. It is currently an illegal drug.

It is a colorless liquid of strong odor that usually appears in a bottle, and is consumed by inhalation. Its effects appear very quickly, but only last a few seconds.

These are: dizziness, feeling of pleasure, increased sexual arousal, relaxation of the sphincters, tachycardia, loss of balance, etc.

It is not known exactly if it has a mechanism of action in the brain, although it has been found that prolonged use can cause neurological damage (Linden, 1990).

10. Hallucinogenic mushrooms

There is a wide variety of mushrooms that contain psilocybin and psilocin, two illegal substances for their psychoactive properties.

The most commonly consumed fungi are psilocybes  and amanita muscaria. They are usually ingested orally, in a very small amount (0.5 – 1.5 grams).

In principle, it seems that they do not produce any type of addiction, and the symptoms vary according to the amount that is consumed. These range from slight perceptual distortions, such as seeing intense lights or colors, to complex hallucinations and even disconnection with reality and mystical experiences.

The experience also depends a lot on the mood of the person, the environment in which they are, their expectations and personal situation.

Also Read: The 14 Most Addictive Types of Legal Drugs

If these conditions are not appropriate, a “bad trip” may appear. This is characterized by a very unpleasant and terrifying experience, which may be accompanied by symptoms of anxiety and psychosis.

It is strange that it causes other complications, long-term health problems or toxicity. However, it is not recommended in people prone to develop psychiatric disorders because this type of drug can trigger them.