Does Pre-Workout Make You Poop?

By: Jeremy Fox, CNC, CPTPublished: November 27, 2023

Have you ever experienced a sudden urge to use the bathroom after taking a pre-workout supplement? It’s not uncommon, in fact, it happens to many people.

The consequences can range from mild stomach discomfort to diarrhea, and that’s the last thing you want during your workout. So, what exactly causes this side effect? Is it the pre-workout supplement itself or is there something else in your routine that’s contributing to it?

Does Pre Workout Make You Poop

In this article, we’ll explore the ingredients that could be causing stomach discomfort and provide some tips on how to avoid them. You deserve to have energy and focus during your workouts without running to the bathroom, and we’re here to help you achieve that.

Can Pre-Workout Really Make You Poop?

It is true that taking a pre-workout supplement can lead to a sudden bowel movement. However, it is not a universal effect and depends on various factors.

To determine if you are likely to experience any toilet trouble, it is helpful to examine the individual components of the pre-workout supplement.

Does Pre Workout Make You Poop

Why Does Pre-Workout Make You Poop?

Pre-workout supplements are a mix of compounds aimed at increasing energy and performance in the gym. However, some of these ingredients may also have unwanted side effects such as stomach discomfort and urgent bowel movements.

While supplement formulations vary significantly between brands, some common ingredients could make you go number two.

Pre-Workout Ingredients That Can Make You Poop

The ingredients in pre-workout that can cause a sudden urge to defecate generally fall into the categories of stimulants, vitamins/minerals, and sweeteners. Here are some specific pre-workout ingredients that can cause bowel movements.

  1. Caffeine
  2. Vitamin C
  3. Vitamin B12
  4. Magnesium
  5. Yohimbine
  6. Sugar Alcohols
  7. Water

Next, I will review these ingredients to explain their effects on your digestive system.

1. Caffeine

Most pre-workout supplements contain caffeine, a stimulant that boosts energy levels before a workout. However, studies have shown that caffeine can lead to an increased urge to defecate, and this effect can occur within just 10-15 minutes of consumption1.

To put things into perspective, a regular cup of coffee contains 80 to 150 mg of caffeine, while pre-workout supplements contain 150 to 400+ mg of caffeine. Therefore, the high doses of caffeine in pre-workout supplements could intensify the urge to poop.

Caffeine In Coffee vs Pre-Workout

This graphic shows the relative caffeine content of coffee vs pre-workout.

2. Vitamin C

Some pre-workout supplements may contain high levels of vitamin C, which can have a laxative effect, according to scientific reviews2. However, these studies refer to mega doses of 2,000 mg or more daily.

In comparison, a pre-workout supplement like C4 only contains 250 mg of vitamin C. Therefore, unless you are particularly sensitive to this vitamin, it is unlikely to cause any issues.

Does Pre Workout Make You Poop - C4 Label

C4 pre-workout contains 417% of the recommended daily value of vitamin C. But that still shouldn’t cause issues for most people. See price on Amazon.

3. Vitamin B12

Some pre-workout supplements contain vitamin B12, which stimulates muscle contraction in the digestive system. This can cause the urge to use the restroom. If you are experiencing this issue, check the label of your supplement for high levels of B12 or other B-complex vitamins.

4. Magnesium

When it comes to supplements that can make you poop, magnesium is at the top of the list. That’s because magnesium oxide and magnesium citrate draw water into the intestines and stimulate bowel activity.

However, only a handful of pre-workout supplements I reviewed contain magnesium, and the dosage is less than the recommended daily intake. For example, BSN N.O.-XPLODE contains only 30% of a day’s supply of magnesium.

Therefore, magnesium probably isn’t the main contributor to your pre-workout poops.

Does Pre Workout Make You Poop - NO Explode

N.O.-XPLODE has 125 mg of magnesium. By comparison, magnesium supplements often contain 400 mg or more. See price on Amazon.

5. Yohimbine

Yohimbine is a compound found in some pre-workout and fat-burning supplements. While it may be an effective stimulant for weight loss, it can also cause an upset stomach and other adverse effects3.

In my experience, taking yohimbe bark extract on an empty stomach can result in “emergency evacuation.” However, supplements with yohimbine HCl seem to cause fewer adverse effects.

Everything You Need to Know Before Taking Yohimbine

6. Added Sugars

In addition, some pre-workouts contain artificial sweeteners known as sugar alcohols for flavoring. However, these zero-calorie additives don’t absorb well in the gut and can cause diarrhea in some people.

Understanding Net Carbs In Sugar Alcohols

7. Water

Lastly, unless you’re “dry scooping,” you probably mix your pre-workout powder with water. Drinking a glass of water is a surefire way to get your digestive system moving, especially in the morning.

One way around this is to take your pre-workout with less water. As little as 3 ounces is usually enough to dissolve the powder. Just make sure you drink plenty of water throughout the day!

Calculate Your Daily Water Intake

How Much Water Should You Drink A Day

Other Factors Relating to Pre-Workout Poops

So far, we’ve talked about the ingredients in pre-workout. But how and when you take these supplements can also affect whether you visit the throne after.


As you probably know, the little plastic scoop provided inside the container dictates the serving size. But a full scoop isn’t the correct dosage for everyone.

If you’re experiencing side effects like jitters or running to the bathroom, then consider scaling back to half of a scoop. Once the symptoms subside, you can gradually increase your dose if necessary.


Of course, you take a pre-workout shortly before starting your training. But whether you work out in the morning or the evening could result in different effects after you take it.

In other words, you’re less likely to experience undesirable consequences if you take pre-workout later in the day.

How Long Does Pre-Workout Take to Kick In?

How Long Does It Take Pre-Workout to Kick In

Empty Stomach

Another factor is how much food you have in your stomach. Taking pre-workout on an empty stomach is more likely to cause immediate poops or digestive discomfort.

That means you could be better off taking your supplement with a healthy pre-workout meal.

Pre-Workout On Empty Stomach:

Pre-Workouts That Won’t Make You Poop

If you find that your pre-workout is making you poop, then the solution could be as simple as changing brands. Start by looking closer at the label to see how much caffeine and other ingredients your pre-workout has.

Stimulant Free

Caffeine is the most likely poop-inducing ingredient. So you might want to test out a stim-free pre-workout like Genius Pre. Otherwise, you can choose one with a lower dose or scale back your serving size.

Minimal Mixtures

A second option is taking a pre-workout supplement with fewer ingredients. With less stuff in the mix, you decrease the chance of side effects and narrow down the possible culprits should you have an issue.

Homemade Pre-Workout

Brand name pre-workouts are a gamble. Some companies hide ingredients and doses behind proprietary blends, so knowing what you’re getting is hard.

I started making pre-workouts at home using the active ingredients found in store-bought supplements. This DIY approach saves money while giving you complete control over what you put in your body.

Click here to see my 5 Homemade Pre-Workout Recipes.

More Pre-Workout Answers

Your pre-workout can intensify your workouts as well as your trips to the toilet. But now you know what ingredients to watch out for to mitigate the risk. And how to take your pre-workout to ease your stomach.

If you found this article enlightening, make sure you check out some of my other pre-workout and supplement information below!

7 Benefits of Salt In Pre-Workout & How Much To Add

Coffee vs Pre-Workout: Which Is Better Before Exercise?

Are Pre-Workout Gummies Worth The Money?

Signs You’re Addicted to Pre-Workout Supplements

Can Pre-Workout Cause Anxiety? How to Reduce Side Effects

7 Best Cheap Pre-Workout Supplements By Category

If you’re up to speed on pre-workout supplements, check out some of my other fitness-related content below. You’ll find information on other supplements, nutrition, workouts, and bodybuilding news.

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By |November 27, 2023|Supplements|0 Comments
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