What is a Stimulant?

Lucy Bell-Young

by Lucy Bell-Young

28th July 2021

A stimulant is any substance that has the pharmacological effect of speeding up the communication between the brain and the body, or ‘stimulating’ it. Stimulants can make the heart beat faster and heighten alertness. In general, there are two types of stimulants: prescription stimulants, such as Ritalin, and illicit stimulants, such as cocaine.

What Do Stimulants Do?

Stimulants temporarily boost your metabolic rate, triggering all sorts of physiological responses that are similar to the fight or flight instinct. For example, a stimulant might cause your breathing rate to increase, resulting in the lungs becoming more efficient at absorbing oxygen and expelling carbon dioxide.

Some stimulants, like coffee, are perfectly legal, but others, like cocaine, are illicit drugs that can have serious debilitating effects.

Hand holding a single adderall pill

What Are the Different Types of Stimulants?

Stimulants can be classified into two main groups: legal stimulants and illicit stimulants. 

Legal stimulants can either be prescriptive, such as in the case of amphetamine, which is used for treating ADHD, or they can be ingredients in legal products, such as tobacco and coffee. 

Illegal stimulants, like cocaine, are prohibited because of their addictive and detrimental effects. Nonetheless, even legal stimulants are potentially addictive, which is why these types of drugs are regulated.

Stimulants are just one of the several major categories of recreational and potentially addictive or detrimental drugs. In terms of physiological effects, stimulants (‘uppers’) are the exact opposite of depressants (‘downers’).

Stimulants create euphoric sensations and elevated moods because they increase the dopamine levels in the brain. This happens because some stimulants, like methamphetamine, mimic the chemical identity of dopamine by binding with dopamine receptors in the brain. 

Depending on the type of stimulant, the euphoric effects can last from a few minutes to a few hours. People who become addicted to stimulants have to take higher doses of the drug to continue experiencing the euphoric effects. 

Examples of Prescription Stimulants

Prescription stimulants are used to help manage hyperactive or inattentive behaviour. They work by helping the brain find focus and calm down. However, excessive intake can cause insomnia, decreased appetite, and weight loss. The side effect of insomnia is particularly detrimental because long-term sleep deprivation can lead to depression, immune system suppression, hallucinations, organ failure, and even death. This is why legal stimulants are still strictly regulated, and why you should never exceed the recommended dosage. 

Here are some examples of prescription stimulants:

  • Ritalin: This is a brand name with the chemical name methylphenidate. Its chemical formula is C14H19NO2. Ritalin can be used to treat ADHD, or attention deficit hyperactivity disorder. Some of the serious side-effects of ritalin include the ones listed below. If a patient experiences any of these side-effects, a physician should be consulted.
    • Chest pain
    • Trouble breathing
    • Lightheadedness
    • Hallucinations
    • New behavior problems
    • Aggression
    • Hostility
    • Paranoia
  • Adderall: This is a combination medicine composed of amphetamine and dextroamphetamine. It’s also used to treat ADHD, as well as narcolepsy, a brain condition that means the person falls asleep at random times. It is known to be abused by teenagers and young adults because of its positive effects in boosting confidence and concentration. 
  • Concerta: This is chemically the same as Ritalin, with the only difference being the brand name.
  • Dexedrine: This drug is similar to Adderall for prescription purposes, but it’s chemically similar to methamphetamine. It can be very addictive and the withdrawal symptoms are agonising for people who become dependent on it.
  • Vyvanse: This is the brand name for lisdexamfetamine dimesylate. It’s used to treat ADHD, binge eating, and other behavioural disorders.
Book with adderall molecular structure typed on it
Adderall is one of the common prescription stimulants used to treat ADHD

Examples of Illicit Stimulants

Unlike commercial and medical stimulants, illicit stimulants are illegal and detrimental to health — both physically and psychologically. As you can imagine, they’re also highly addictive. Here are some examples of illicit stimulants:

  • Ecstasy: This drug, otherwise known as MDMA (MethyleneDioxyMethAmphetamine), is a stimulant that’s popular among party-goers. It allows those who take it to feel euphoric and highly energetic. It also has hallucinogenic effects and stimulates the pleasure centre of the brain. However, it actually depreciates the amount of dopamine in the brain, thereby increasing the desire to take a higher dosage.
  • Methamphetamine: More commonly known as crystal meth or simply ‘meth’, this stimulant is a highly addictive drug. It’s usually in the form of white powder, but can also be sold as a small blue-white crystal. The euphoric and high energy effects of this drug can last for several hours. Under strict medical supervision, the drug can be used as a second-line treatment for obesity.
  • Cocaine: This drug is derived from the coca plant native to South America. It’s processed and sold as a white powder. Formerly considered to be a recreational drug for the rich, its decreasing price has made it more accessible to everyone. Cocaine is a very dangerous drug that can lead to respiratory failure, brain haemorrhage, or heart attack.

What is a Chemical Stimulant?

All chemical stimulants are psychoactive drugs that affect the normal functions of the brain. These drugs heighten alertness, focus, and the sense of euphoria. Whether it’s naturally occuring, like nicotine in tobacco, or something synthetic, like methamphetamine, a stimulant works by mimicking or interacting with some of the biochemicals in the central nervous system.

While chemical stimulants are metabolised by the body, they cause dependency as they boost some chemicals in the brain, like dopamine. The ‘high’ that’s achieved by taking these drugs essentially messes up the normal electrochemical functions of the brain.

The Chemistry Behind Stimulants

All stimulants have very similar effects on the central nervous system. Despite the varieties of stimulants and differences in composition, they operate in similar ways mainly because they have similar molecular structures. Refer to the illustration below for the molecular structures of methamphetamine, amphetamine, and ecstasy:

Stimulants have two main pathways in affecting the electrochemical activities of the brain. Firstly, they increase the level of catecholamine chemicals, like adrenaline and dopamine. Secondly, they bind with the dopamine transporters, which results in the inhibition of dopamine reuptake. In this way, the stimulants induce a greater production of dopamine, flooding the pleasure receptors of the brain.


All content published on the ReAgent.ie blog is for information only. The blog, its authors, and affiliates cannot be held responsible for any accident, injury or damage caused in part or directly from using the information provided. Additionally, we do not recommend using any chemical without reading the Material Safety Data Sheet (MSDS), which can be obtained from the manufacturer. You should also follow any safety advice and precautions listed on the product label. If you have health and safety related questions, visit HSE.gov.uk.