Ever wonder why sipping a cocktail after a long day makes you feel relaxed, or why your eyes turn red after smoking a joint? We take a look at the physical and psychological effects of drugs on your body and brain.

Effects of Drugs on the Body and Brain

Millions of people around the world consume drugs each and every day – from a cocktail after work to unwind, to a line of cocaine or a hit of ecstasy to keep up energy on the dance floor. But have you ever stopped to wonder what exactly these drugs are doing to your brain in order to create these desired effects? Aside from setting you up for drug addiction, substances are causing your mind and body to work in unnatural ways.

We take a look at the most commonly abused substances, and how they alter the brain and body with use.

5 Popular Drugs on Your Body and Brain


Despite being legal (and widely consumed) in many countries around the world, studies have found that alcohol is actually the most dangerous drug on the market – even above heroin and cocaine. Over three million deaths are attributed to alcohol abuse each and every year. Alcohol is a depressant, and the effects on the mind and body include:

  • Increased levels of dopamine in the brain, giving you the impression that alcohol makes you feel better (happier, less stressed, etc.).
  • Slowed thinking, breathing and heart rate within minutes of consumption. This is one of the reasons that drinking too much can kill you.
  • Generally, your liver can only process the equivalent of 25ml (one shot) of alcohol per hour. Drinking at a rate faster than that can quickly and dangerously increase your blood alcohol content.
  • In those who drink heavily, 90% develop fatty liver disease which can cause fatigue, weight gain and pain.
  • Frequent consumption can cause damage to the links between neurons in your brain, which affects your ability to process information.
  • Alcohol can create a feeling of fearlessness which can lead to accidents, physical fights and injury.
  • Possibility of developing an addiction.


As the legalisation of marijuana is increasing around the globe, it is even more important to understand how this drug actually affects you, which is as follows:

  • Changes in the brain related to information processing
  • If you are familiar with weed, you are familiar with getting red eyes. Red eyes are caused by the expansion of blood vessels after using marijuana.
  • Increased appetite, or ‘the munchies’ because marijuana essentially flips a switch on the part of the brain that’s responsible for moderating appetite
  • Influences two brain areas which regulate balance, coordination, reaction time and posture
  • Feelings of euphoria caused by the release of dopamine in your brain
  • Sometimes causes hallucinations
  • Increases your heart rate by 20-50 beats per minute. This can last from 20 minutes to several hours.
  • Can cause feelings of anxiety or panic, especially in those already prone to anxiety and panic.
  • Possibility of developing an addiction


Opioids include prescription pills such as OxyContin, Percocet, Vicodin, and fentanyl as well as the street drug heroin. All opioids have the following effects on the user, although the severity and presence of each symptoms depends on the amount taken and how it’s administered:

  • Constricted pupils
  • Slowed breathing – overdose can completely stop breathing causing brain damage, coma or death.
  • Stopping the drug causes severe withdrawal symptoms, which increases the risk and speed of developing an addiction.
  • Opioids bind to pain receptors, relieving the body of pain, both physically and mentally in many cases.
  • Opioids reduce the amount of GABA in the brain, which in turn increases the amount of dopamine in the brain.
  • Flushed, warm skin
  • Constipation and gastrointestinal issues
  • Effects last on average 4 to 12 hours.
  • Possibility of developing an addiction


Cocaine begins affecting the brain and body within seconds, in the following manner:

  • Dilated pupils as a side effect of increased serotonin levels in the brain
  • Increased heart rate and blood pressure
  • Snorting cocaine regularly can create holes in parts of the nose, often the septum.
  • Smoking cocaine can irritate the lungs, sometimes causing permanent lung damage.
  • Injecting cocaine can lead to damaged veins, and possibility of contracting blood-borne diseases when needles are shared.
  • Reduces the body’s ability to store fat, leading to weight loss at dangerous levels
  • Decreased appetite
  • Nosebleeds are common, especially in those who snort the drug
  • Blocks absorption of serotonin and dopamine, creating a feeling of intense euphoria
  • Feel more energetic or alert, but also frequently more irritable, anxious or paranoid
  • Cocaine constricts arteries, which can lead to heart attack.
  • Possibility of developing an addiction

Ecstasy (Molly, MDMA)

Whether in a tablet known as ecstasy, or a crystallized powder in a capsule known as Molly, the effects of MDMA are typically as follows:

  • High levels of serotonin and dopamine are released, causing users to feel extremely happy, more social, and experience an increased level of empathy towards others.
  • Cortisol, the ‘stress hormone’, is also released, causing difficulties in sleeping after taking the drug.
  • Enhanced sensory perception
  • Excessive sweating can cause serious dehydration.
  • Involuntary jaw clenching
  • Feelings of increased energy and the inability to sit still for long periods of time
  • Feelings of depression, irritability and fatigue the day after use due to lower levels of serotonin in the body
  • The effects last, on average, three to eight hours
  • Possibility of developing an addiction

The Common Thread: Addiction

All of the drugs mentioned above create an overload of dopamine in the brain, which can in turn lead to addiction. (For a full explanation of the role of dopamine in developing an addiction, see: Drug Abuse, Dopamine, and the Reward System Explained). From marijuana or alcohol to heroin and cocaine, addiction is a problem for many who choose to use these drugs recreationally.

If substance abuse is causing negative consequences in your life and yet you are still unable to quit using on your own, there is a good chance you have developed an addiction.  If you want to quit using and get your life back on track, contact us today for a free consultation with an addiction expert to see how we can help.

Are Drugs Taking Over You Life?

About the Author

Lee Daniel Hawker-Lecesne

Lee Daniel Hawker-Lecesne

Clinical Director at The Cabin (MBPsS, British Psychological Society Number: 479469) Lee is a Registered Member of the British Psychological Society. He graduated from Anglia Ruskin University in the UK with a degree in Behavioural Science and a postgraduate clinical focus on addictions from the University of Bath. Lee is a focused and ambitious individual who has in-depth training and experience in a broad range of clinical psychological interventions in the treatment of addiction, dual diagnosis, and complex trauma.

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