There is no doubt that pre-workout can boost workout performance, but one of the common questions I get as a fitness professional is whether this popular supplement is bad for your brain.
To give my clients an accurate answer and hopefully put their minds at ease, I went over a few scientific studies on the subject and consulted our dietician about the common ingredients in pre-workout and their impact on the brain.
Read on to find out what I learned.
Quick Summary
- A pre-workout supplement isn't bad for the brain, but it is linked to some side effects like headaches, and jitteriness.
- Caffeine, L-citrulline, creatine, and nootropics are some of the ingredients found in pre-workout supplements.
- Some people taking pre-workouts might experience insomnia, restlessness, and anxiety because of caffeine.
Is Pre-workout Bad for Your Brain?

Pre-workout is not bad for your brain, but it does come with some risk of side effects, including jitteriness and headaches.
Let’s examine this popular workout supplement a bit closer.
Ingredients
Let’s first look at the most common pre-workout ingredients and how they may affect the brain.
Caffeine
The most common ingredient in many pre-workout supplements is caffeine.
Caffeine is a central nervous system stimulant that most know improves energy and alertness, but it is also proven to enhance exercise performance [1].
Caffeine can improve many aspects of brain function [2].
These include:
- Vigilance
- Mood
- Learning
- Reaction Time
- General cognitive function
- Attention
- Alertness
However, caffeine withdrawal symptoms might include headaches, and over the course of the abstinence crisis, it might actually cause the reverse of the aforementioned effects.
L-Citrulline
L-Citrulline is added to pre-workout to boost nitric oxide production and increase blood flow [3]. This increased blood flow helps hard-working muscles during a workout to get you better pumps and benefits the brain in several ways [4].
Some of these include:
- Increased energy
- Increased oxygen
- Improved mental clarity
- Boosted memory
- Increased cognitive capacity to think clearly and make decisions
- Improved problem-solving skills
Creatine

When people think about creatine in pre-workout supplements, they understand its benefit to muscle growth and recovery.
Additionally, many studies suggest that creatine benefits cognitive function [5].
More research shows that creatine supplementation of 5-20 grams daily may improve healthy adults’ short-term memory and reasoning ability [6].
Nootropics
Many popular pre-workout supplements contain nootropics, also known as cognitive enhancers or “smart drugs”.
In pre-workout, they are not drugs but natural ingredients that improve cognitive function [7].
Nootropics can enhance brain function in the following ways:
- Increase focus and clarity
- Increase motivation to perform tasks
- Improve understanding
- Boost memory and knowledge retention
- Reduce mental fatigue
- Reduce boredom
- Improve brain health
- Improve mental acuity
- Improve reaction time
- Heighten mood
- Boost creativity
Examples of nootropics in pre-workout include:
- L-theanine
- Creatine
- Rhodiola Rosea
- Acetyl L-Carnitine
- L-Tyrosine
- Vitamin B12
- Caffeine
“L-theanine is an amino acid found in tea that can increase feelings of calmness and may be linked to increased creativity. Its effectiveness is even greater when combined with caffeine.”
- Erica Julson, MS, RDN
Uses

The most common practice is taking a pre-workout supplement before exercise to enhance athletic performance and increase stamina and energy.
Additionally, pre-workout can improve focus for studying, increase mental function for work or school, or increase mental energy for a late-night cram session.
Side Effects
Most side effects from pre-workout supplements come from the stimulants they contain.
These include:
- Jitteriness
- Anxiety
- Headaches
- Insomnia
- Restlessness
- Drowsiness
How to Safely Use It

For most people, pre-workout supplements are safe.
It is always best to consult your doctor before using any supplement, including pre-workout, to discuss any underlying medical conditions or medication interactions.
Also, to minimize potential adverse effects, do not take a higher dose than the manufacturer suggests.
If you are sensitive to stimulants, you can cut the dose in half to see if that helps with any side effects.
Related: Is Pre-workout Bad for Your Teeth?
FAQs
Does Pre-workout Mess With Your Head?
Pre-workout can mess with your head, likely due to stimulants. Caffeine is the most common stimulant in pre-workout supplements that can cause anxiety, restlessness, and insomnia.
Headaches are another side effect of stimulants and citrulline, another common pre-workout ingredient.
Does Pre-workout Affect Serotonin?
Pre-workout can affect serotonin which helps regulate behavior and attention. If pre-workout contains caffeine, it increases the serotonin neurons in the brain leading to improved mood and energy levels [8].
So, Is Pre-workout Really Bad for Your Brain?
My research suggests that pre-workout supplements themselves are not harmful to your brain, but some ingredients may cause adverse effects like headaches or anxiety.
Since there is no shortage of pre-workout options, we research and test many products here at Total Shape to make finding the right one easier for our clients.
Check out our lists of best pre-workout supplements here:
Top picks on our lists proved to be reliably effective with many of our clients without causing any of the commonly reported side effects.
References:
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739593/
- https://onlinelibrary.wiley.com/doi/full/10.1111/j.1467-3010.2007.00665.x
- https://www.webmd.com/vitamins-and-supplements/l-citrulline-uses-and-risks
- https://www.scientificamerican.com/article/why-do-you-think-better-after-walk-exercise
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7916590/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6093191/
- https://www.webmd.com/vitamins-and-supplements/features/nootropics-smart-drugs-overview
- https://pubmed.ncbi.nlm.nih.gov/1356551/
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