How Drugs Are Classified

Each drug is unique and has totally different effects from others. In this article, we're going to explore how drugs are classified.

Written and verified by the psychologist Laura Ruiz Mitjana.

Last update: 05 June, 2023

Drugs are substances that create alterations in the cellular connections of the central nervous system and therefore affect behavior, also producing various alterations at the perceptual level. But, how are drugs classified?

Firstly, not all drugs have the same effects or the same nature, nor are they equally dangerous. So, what criteria are used to classify them? And what different kinds of drugs are there? Find out here.

How are drugs classified?

Drugs are classified based on different criteria. One of them is the effect that they cause on the body. In this respect, there are three types of drugs: hallucinogenic, depressant, and stimulant.

1. Hallucinogenic drugs

These are chemical compounds that affect brain connections, causing us to perceive reality in an altered way. They owe their name to the fact that they can create hallucinations or abnormal perceptual experiences.

A study conducted by the Cleveland Clinic (USA) states that hallucinogens alter an individual’s awareness of their surroundings. Some are man-made, while others are derived from natural compounds, such as plants and fungi.

Some examples of these drugs are LSD, mescaline, and ecstasy (MDMA). They’re also known as disruptive drugs. This is because they’re capable of modifying mental activity, producing a wide variety of effects on the nervous system.

According to the National Institute on Drug Abuse, hallucinogens temporarily alter mood, thinking, and perception of reality. In addition, the specific short-term effects are:

• Increased blood pressure, respiratory rate, and body temperature.
• Loss of appetite.
• Dry mouth.
• Sleep disorders.
• Crossing of sensations or synesthesia.
• Spiritual experiences.
• Sensations of relaxation or separation from the body or environment.
• Uncoordinated movements.
• Excessive sweating.

2. Depressant drugs

Depressant drugs are those that depress the nervous system (such as alcohol). Their intake implies a suspension or a decrease in brain responses, and they slow down nerve stimuli.

These are drugs that ‘calm down’ the body. They leave the body in a state of torpor and total inactivity. In this group are sedatives or hypnotics, opioids, and neuroleptics. Examples are cannabis, alcohol, heroin, and benzodiazepines.

According to experts from the Queensland Alcohol and Drug Support Service (ADIS), the short-term effects of this class of drugs are dizziness, lack of balance and coordination, as well as slower reflexes. In large doses, they can cause drowsiness, nausea, and loss of consciousness.

Experts from the National Institute on Drug Abuse suggest that central nervous system depressants can lead to:

• Speech distortions.
• Lack of concentration.
• Confusion.
• Headache.
• Dizziness.
• Dry mouth.
• Motor and memory problems.
• Decreased blood pressure.
• Slow breathing.

3. Stimulant drugs

Finally, stimulant drugs (such as amphetamines) produce an increase in the levels of alteration (nervous and motor excitation). When ingested, the individual enters a state of euphoria and lacks control. This is manifested in their reactions and actions.

Stimulant drugs include amphetamines, cocaine, caffeine, nicotine, theobromine, and theophylline.

Depending on the amount of the dose (high or low), stimulants produce certain effects. A small dosage produces:

• Euphoria.
• Feelings of well-being.
• Increased heart rate.
• Increased alertness.
• Loquacity.
• Reduced appetite.

A high dosage causes:

• Anxiety.
• Tension.
• Increased body temperature.
• Nausea.
• Shaking.
• Seizures.

Stimulants, like other types of drugs, can have extremely serious health consequences. The most general, according to an article published in StatPearls, are the following: psychosis, paranoia, anxiety, arrhythmias, hypertension, tachycardia, breathing problems, cerebrovascular events, and sudden death, among others.

Drugs are classified according to their origin/nature

Drugs are also classified according to their origin or nature. There are natural, synthetic, and industrial drugs.

1. Natural drugs

Natural drugs are those that have not gone through any process of chemical intervention. Thus, they’re obtained from nature. For example, marijuana, opium, coca leaf, peyote, hallucinogenic mushrooms, and tobacco.

2. Synthetic drugs

Synthetic drugs are obtained from different chemical processes, which are necessary to refine their composition and degree of purity. After these processes, they can be marketed and distributed. Some examples are amphetamines, methamphetamines, benzodiazepines, ecstasy, and ketamine.

3. Industrial drugs

Finally, industrial drugs are formed through industrial residues. Their high chemical composition, when inhaled, generates hallucinogenic effects. One example is industrial glue.

Drugs are classified based on their legality

Drugs are also classified based on their legality (according to the legislation of each country). According to this criterion, there are two types of drugs:

1. Legal drugs

Legal drugs are permitted psychoactive substances. This means that their use isn’t penalized by law. However, the legality of drugs varies from country to country. Furthermore, a drug may be legal for consumption, but not for sale.

The legality of drugs doesn’t correspond to their danger. For instance, there are legal drugs whose abuse is highly dangerous and harmful to health. Within this group of drugs are:

• Alcohol.
• Nicotine.
• Caffeine.
• Theobromine and theophylline.

2. Illegal drugs

Illegal drugs are psychoactive substances. Their usage isn’t permitted by the country’s law. However, it may be the case that their consumption is allowed in certain circumstances, but that their sale is penalized. The most consumed illegal drugs are:

• Marijuana.
• Hashish.
• Cocaine.
• MDMA.
• Phencyclidine or PCP.
• Heroin.
• Poppers.
• Hallucinogenic mushrooms.

A less-used classification

As you can see, there are a number of ways of classifying drugs. In fact, there are even more classifications. For example, the popular classification, in which drugs are classified as soft or hard.

Soft drugs are those that are more socially accepted (perceived as less harmful). On the other hand, hard drugs are viewed as having a greater social and health impact, since their use is more dangerous in the short term.

Examples of soft drugs are tobacco, alcohol, and marijuana. While hard drugs include heroin, morphine, and amphetamines, among others.