A pre-workout supplement is a great way to increase energy, enhance focus, and boost workout capacity, but it can come with some downsides. Taking too much pre workout can lead to increased heart rate and blood pressure, paraesthesia, water retention, and digestive upset, so limiting your dose is advised.

Pre-workout supplements have been all the rage for several years now, and there’s a good reason they’re some of the most popular and widely used fitness supplements on the market. If you’re looking for more energy, strength, or endurance, a pre-workout might be for you.

But there’s one area where people seem to struggle: dose. How much is enough to see benefits? For most conventional pre-workouts, there’s a fine line between just enough and too much—and crossing the line can lead to some unwelcome side effects.

Whether you’ve been contemplating a double scoop or just treading into pre-workout waters, we’re going through the risks of taking too much pre-workout and five reasons that less may be more.

What Causes Pre-Workout Side Effects?

While most pre-workout supplements will provide a recommended dosage, most people don’t follow them; it’s more about experimenting with a dose that offers benefits with minimal side effects. For some people, that could be a double scoop, while for others, it could be a half—it all depends on the individual.

But in any case, the side effects experienced from pre-workouts are typically the result of a few things: wrong serving size, proprietary blends with dodgy ingredients, and excessive caffeine (or other stimulants).

1. Improper serving size

Any pre-workout or nutritional supplement is required to have a recommended serving size, but for those looking for a big pump, one scoop of pre-workout might not be enough.

So, naturally, we double up. But the recommended serving size represents how much pre-workout is required to achieve optimal effects.

Increasing or decreasing your intake could interfere with how it’s designed to work and lead to an ineffective product or adverse effects.

More isn’t always better, especially when you have a product loaded with stimulants, nitric oxide boosters, and other performance-enhancing ingredients. In this case, too much can be detrimental to your workout.

2. Proprietary blends

If you’re unsure how much of each ingredient is in your supplement, chances are you should stay clear of it.

Many manufacturers choose to release their products under the label of a proprietary blend—they’re a blend of ingredients in specific doses that are considered “trade secrets.” They’ll release what’s in the blend, but they won’t release the doses.

And although proprietary blends aren’t the worst thing you can take, not knowing how much of something is in your pre-workout can be the reason you’re experiencing side effects, so it’s best to avoid anything with proprietary blends.

3. Excessive caffeine

Excessive caffeine is at the root of many nasty pre-workout side effects, whether nervousness, jitters, anxiety, or digestive upset.

While moderate amounts of caffeine can be super beneficial for performance—they’ve been shown to increase focus and enhance performance during high-intensity activity—high doses of caffeine can hurt your performance.

But what’s interesting (and something most people aren’t aware of) is that higher doses of (≥ 9 mg/kg) don’t offer any additional benefits over moderate amounts—they increase the risk of adverse reactions 1.

Risks Of Taking Too Much Pre-Workout

1. It can increase your heart rate

Have you ever downed a scoop of pre-workout only to feel like your heart is about to fly out of your chest? Say hello to caffeine, a central nervous system stimulant that binds to receptors in the heart to increase heart rate and produces acute increases in systolic and diastolic blood pressure 2.

In moderate doses, an increased heart rate can help pump blood more effectively to active muscle tissue and increase muscle strength and output during exercise.

Still, too much can lead to a host of nasty symptoms associated with overstimulation, including insomnia, nausea, drowsiness, headaches, anxiety, and jitters 3-6.

For comparative purposes, the average pre-workout supplement contains anywhere from 200 to 300 mg of caffeine per serving, while one cup of coffee contains only 5 mg.

How to reduce side effects:

The proper caffeine dosage is highly individualized, as some people can tolerate higher doses than others. But the best way to mitigate the nasty side effects of caffeine is to reduce your dose—start small and increase incrementally until you find the sweet spot.

Alternatively, stick to a moderate amount in a pre-workout that contains synergistic ingredients, like Pre Lab Pro. It combines moderate-dose caffeine with L-tyrosine and L-theanine for optimal stimulation while protecting against side effects.

2. It can lead to water retention

Some people find that overdoing it on pre-workout can lead to water retention and feeling puffy. In most cases, creatine is the culprit.

It’s one of the most widely researched ergogenic aids consistently shown to enhance high-intensity exercise capacity and support the accretion of lean muscle mass 7. But as great as creatine may be (and it’s proven safe), it comes with a potential downside—water retention.

Bloating and water retention is most commonly associated with creatine loading—consuming doses of 20-25g of creatine daily for 5-7 days to maximize muscle creatine stores.

While the theory behind why creatine loading makes sense for performance, high doses can lead to unpleasant symptoms like gastric distress, muscle spasms and strains, and cramping.

Water retention occurs because of changes in intracellular osmotic pressure, which results in the movement of water into the cell, causing cells to swell and leaving you feeling bloated and puffy 8.

How to reduce side effects:

Even though creatine is exceptionally safe, overdosing on creatine can be problematic 9, 10. The easiest way to avoid the discomfort associated with pre-workout supplements is to avoid those that contain creatine. If you’re going to take creatine, opt for it in a pure supplement where you can control the dose.

3. It can cause digestive upset

Digestive upset can also result from pre-workout ingestion, but it largely depends on what’s in your supplement.

Things like sodium bicarbonate, magnesium, creatine, and caffeine can all have a laxative effect in high doses, causing digestive issues like diarrhea and nausea. However, this largely depends on the forms of nutrients in your supplement.

For example, magnesium citrate in high doses can lead to diarrhea thanks to its ability to increase water concentration in the small intestine.

Not mixing enough water with your pre-workout can cause GI issues, as an ultra-concentrated supplement isn’t always the best. So, if you’re thinking about dry-scooping your pre, you might want to think again.

How to reduce side effects:

For starters, follow the directions on the label—they are given for optimal preparation and effects. If you’re taking a powdered pre-workout, ensure you’re mixing it with an appropriate amount of water to minimize unwanted effects.

Additionally, try to determine what ingredients are causing the issue and avoid them. You want to look for a clean pre-workout with quality, research-backed ingredients to mitigate the risk of adverse effects.

Not every product you try will be tolerable for you, so experiment and find what works.

4. It can trigger headaches

Again, caffeine is usually the culprit for a headache after pre-workout, but it can also result from nitric oxide boosters like citrulline and arginine. You’ll commonly see these amino acids added to pre-workout supplements to boost NO blood levels, which can help to extend work capacity and support better performance.

However, the blood vessel dilation that happens with NO boosters also applies to the blood vessels in your brain. Because they open, blood flow is increased, which can lead to headaches and migraines in specific individuals. This is caused by blood pressure changes in the small blood vessels of your brain 11.

How to reduce side effects:

The most effective way to reduce headaches and migraines associated with NO boosters (and potentially caffeine) is to lower your dose. If you’re constantly getting a headache after taking your pre-workout, look for one that doesn’t have any NO precursors.

5. It can cause mild reactions

Two other ingredients commonly added to pre-workout supplements that can trigger mild reactions are niacin (vitamin B3) and beta-alanine.

Niacin is a B vitamin that plays a vital role in energy metabolism and can reduce post-workout muscle soreness and enhance recovery. Still, too much of it in the wrong form can lead to what’s called “niacin flush.”

This is generally triggered with doses exceeding 500 mg, as it dilates blood vessels in the skin, leading to a rush of blood to your face 12. Keeping your dose below this threshold can prevent it from happening.

On the other hand, beta-alanine is an amino acid used to buffer acid from muscles to increase exercise capacity.

At doses of 4 to 6 g per day, beta-alanine may improve exercise performance and reduce fatigue during high-intensity activity, but a large single dose of the supplement can lead to serious tingles 13, 14. Although it’s a harmless nervous system reaction, it can be uncomfortable 15.

How to reduce side effects:

If you’re not a fan of pins and needles that can come along with beta-alanine supplementation, your best bet is to choose a pre-workout that doesn’t include it or divide your daily dose into two separate doses of 2-3 g each. You can also buy sustained-release formulas that prevent this from happening.

Final Thoughts

Pre-workout supplements can be a major hit-and-miss, and sometimes, it takes a lot of experimentation to find one that’s right for you. But regardless of what you choose, remember that more isn’t always better.

Doubling up on the dose can lead to an array of unpleasant side effects, both immediate and long-term, so scale back and choose quality over quantity when picking a product.


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