Allergic Reactions to Pre-Workouts: Common Causes and How to Avoid Them

  • By Performance Lab
  • 7 minute read
Allergic Reactions to Pre-Workouts: Common Causes and How to Avoid Them

You know that feeling when you take a supplement—be it a pill, powder, cream, or what have you—and a few minutes later your skin gets itchy, a blotchiness creeps over your entire body, or worse, you get an absolute banger of a headache that kills the rest of your day (and your workout, too).

It’s a complete and utter bummer.

Not only have you probably just canned your workout for the day, but depending on the severity of your reaction, you may be left feeling like an absolute sack of trash.

Admit it; we’ve all had a reaction to something in our lives before.

But when you’re pumped up and ready to hit the gym, you don’t want that reaction to be from your pre-workout.

So, here we have it for you - some of the most common causes of allergic reactions to pre-workout, and how you can avoid them to make sure that the blood rushing through your veins gets put to good use.

Allergic Reaction v. Sensitivity

There’s an important distinction that needs to be made before we go any further. An allergic reaction and a sensitivity are not the same thing. One involves an immune response; the other does not.


An allergic reaction, by definition, is an overreaction of the immune system to a harmless substance.

Under normal circumstances, the immune system defends the body against invading pathogens or foreign substances using white blood cells, mast cells, complement proteins, and other immune substances.

However, in some people, the immune system goes a bit overboard and gets a bit too hyped when it comes into contact with allergens present in the environment, food, or in this case, supplements. The result? You have an allergic reaction.

Here’s how an allergic reaction works more specifically:

When first exposed to any sort of allergen, the immune system produces immunoglobulin E (IgE), an antibody. IgE binds to a class of white blood cells called basophils.

This initial exposure is the instigator of all future reactions if the individual is sensitive to the allergen (a process called sensitization), but doesn’t cause any noticeable symptoms.

If the individual encounters the allergen again, the basophils and mast cells with IgE present on their surfaces release substances that cause a reaction; histamine, prostaglandins, leukotrienes, and the like that generally cause pain, swelling, and inflammation 1.

These substances further irritate tissues, causing anywhere from a very mild reaction to one that’s quite severe.


Ever had terrible gas after downing a whey protein shake? That’s a food sensitivity, or a non-immune mediated response 2.

Unlike an allergy, a sensitivity does not involve the immune system but is triggered by the digestive system because of the inability to digest or process something in whatever you’ve consumed.

The tricky thing is that there can also be non-IgE mediated allergies, which typically have a delayed onset and present in the digestive tract as things like gas, bloating, diarrhea, or vomiting.

There are a few reasons a reaction is triggered:

  1. You lack the enzymes needed to breakdown a certain compound
  2. A reaction to additives (sulfites, artificial colors or flavors, MSG, etc.)
  3. Pharmacological sensitivities (caffeine, chemicals, etc.)
  4. Sensitivity to sugars (artificial sweeteners, sugar alcohols, etc.)

What Causes Allergic Reactions?

What you’re taking and what’s in the product probably causes your allergic reaction.

Receive unique insights, advice and exclusive offers.
image of Performance Lab® capsules

It shouldn’t come as a shocker that most pre-workouts use a mix of ingredients (some low quality and artificial), that drastically increase the chance of having some sort of reaction.

Here are the most common reasons for having an allergic reaction to pre-workout:

1. You’ve Taken Too Much

“If I take more, I’ll get a better pump, right?”

Well, no, it doesn’t really work like that…

The dosage on the bottle is there for a specific reason, because it’s been tested at that dose and it’s the dose that elicits the most favorable effects and the least side effects.

Taking too much pre-workout will probably do the complete opposite of what you want, especially if it’s heavy on the stimulants.

The other thing with taking too much pre-workout is it can cause a sort of reaction in your body; not necessarily an allergic reaction, but a less than pleasant one.

Beta-alanine is a common ingredient added to most pre-workout supplements because it can boost intramuscular carnosine synthesis, which acts as a buffer to prevent muscle cells from becoming acidic, thereby decreasing fatigue 3.

But a common side effect of taking too much beta-alanine is skin paresthesia, which includes itching and tingling.

And because beta-alanine is widely distributed in the muscles, nervous system, and skin, it causes a reaction that’s usually felt in the face, neck, and back of the hands.

Learn more about beta-alanine itch and what to do about it.

It should go without saying that overloading on a pre-workout containing caffeine (or any other stimulant) can also give you an adverse reaction and some serious jitters.

To avoid ruining your workout before you even start, keep an eye on the amount of caffeine in your pre, or better yet, find a stim-free blend like Performance Lab Pre.

2. It’s Loaded With Synthetic Additives (color, flavor, etc.)

Your pre-workout may taste like delicious juicy blue raspberry or Fuzzy Peach, but it may not be doing you any good.

Additives and synthetic ingredients are one of the most common causes of allergic reactions, and it usually comes in the form of artificial sweeteners.

Sugar isn’t the way to feed a good workout, so manufacturers replace the sugar with an artificial, calorie-free alternative that the body doesn’t recognize, so they pass through the digestive tract intact.

It’s long been thought that these alternatives have minimal effect on the body, but that’s not true. They’ve been shown to 4, 5:

  • Disrupt the gut microbiome
  • Increase the risk of metabolic disorders
  • Cause gastric discomfort

Not to mention they also cause things like headaches, dizziness, mood changes, diarrhea, gas and bloating, and inflammation.

Watch out for these:

  • Aspartame—200x sweeter than sugar
  • Acesulfame (ACE)—200x sweeter than sugar
  • Sucralose—650x sweeter than sugar
  • Saccharin—300-400x sweeter than sugar

Be mindful that even ‘natural’ alternatives like xylitol, sorbitol, and maltitol can still wreak all sorts of havoc. They can pull water into your gut and serve as a food source for bacteria, which may cause digestive discomfort in some people.

3. It Contains Niacin

Hives and rashes are the common side effect of taking pre-workouts containing niacin (vitamin B3).

As a B vitamin, among all its other important benefits, it helps with energy production to fuel your workouts, thereby sending nutrients to your muscles that aid in muscle growth.

But the problem with the amounts found in most pre-workouts is that it causes something called ‘niacin flush.’

Amounts exceeding 20mg, the RDA for niacin, can dilate your blood vessels and send them into overdrive, causing the redness or flushing which results 6.

Common Symptoms of Allergic Reactions

If you’re having a reaction of any sort to a pre-workout, chances are you’ll know.

Watch out for these symptoms:

  • Itching
  • Swelling
  • Hives or rashes
  • Headaches
  • Anaphylaxis (difficulty breathing, wheezing, dizziness)
  • Digestive symptoms (gas, bloating)

Here’s How You Can Avoid Them

1. Follow The Dose On The Bottle

If it says to take two capsules (or x scoops) 30 minutes before a workout, follow those guidelines!

It prevents any negative side effects like nausea, diarrhea, itching, or tingling from popping up mid-workout and sending you out the door.

As we mentioned before, the dose on the bottle is also the most effective, so do yourself a favor and stick to it.

2. Look For Clean Supplements

Know what’s in your pre-workout. We can’t stress that enough. If you’re reading the ingredients and only know what 50% of them are, put it down—it’s time to find a new pre.

But if you want to avoid reactions to anything in the formula, make sure you know what’s in it and be aware of any ingredients that may not work with your body. Less is more when it comes to nutritional supplements.

Performance Lab Pre is a cleaner, smarter pre-workout and one of the most effective, stim-free muscle primers on the market designed to power you through high-intensity workouts.

Intelligently stacked to boost and sustain nitric oxide (NO) levels for twice as long and nourish your muscles to protect against the build-up of lactic acid that can end sessions early.

3. Stay Hydrated

If you’re prone to headaches after taking pre-workout, it can be either a reaction to a specific ingredient in your pre-workout or from dehydration.

Creatine, for example, pulls water from other areas of the body to support working muscles 7, which can cause mild dehydration.

High-intensity training will also cause dehydration, so ensure you’re consuming fluids pre-, intra-, and post-workout to keep yourself adequately hydrated.

4. Avoid Taking Your Pre- Too Close To Bedtime

This one’s especially important if you’re an evening lifter because insomnia can be another nasty side effect of high-stim pre-workouts.

As caffeine stays in your system, on average, anywhere from 4 to 6 hours, if you’re training at 8 pm and taking a pre-workout, chances are your sleep is going to suffer, and your recovery suffers as a result, too.

However, if you’re taking a stim-free formula, you need not worry so much about when you’re taking it because it probably won’t have much of an effect on your sleep.


  1. S Waserman, P Bégin, W Watson. IgE-mediated food allergy. Allergy Asthma Clin Immunol. 2018; 14(Suppl 2): 55.
  2. S Anvari, J Miller, CY Yeh, CM Davis. IgE-Mediated Food Allergy. Clin Rev Allergy Immunol. 2019; 57(2): 244-260.
  3. Q Lui, P Sikand, C Ma, Z tang, L han, et al. Mechanisms of Itch Evoked by β-Alanine. J Neurosci. 2012 Oct; 32(42): 14532–14537.
  4. FJ Ruiz-Ojeda, J Plaza-Díaz, MJ Sáez-Lara, A Gil. Effects of Sweeteners on the Gut Microbiota: A Review of Experimental Studies and Clinical Trials . Adv Nutr. 2019; 10(suppl_1): S31-S48.
  5. MY Pepino. Metabolic effects of non-nutritive sweeteners. Physiol Behav. 2015; 152(Pt B): 450-455.
  6. FDA Vitamins and Minerals Chart (available online at
  7. ME Powers, BL Arnold, AL Weltman, et al. Creatine Supplementation Increases Total Body Water Without Altering Fluid Distribution. J Athl Train. 2003; 38(1): 44-50.