Can pre-workout make you need to poop?

If you have ever taken pre-workout, there is a very good chance that you have needed to poop not long after drinking it. This rush to the bathroom is due to certain ingredients in the supplement that have an effect on bowel movements.

A typical pre-workout supplement will contain a number of ingredients such as creatine, artificial sweeteners, beta-alanine, BCAAs, etc. Many of these ingredients can cause unpredictable bowel movements.

A healthy diet determines bowel movements which can consist of food, water and supplements. However, adding some ingredients found in pre-workout supplements can cause a disruption in the colon and even diarrhea.

Pre-Workout Ingredients That Make You Need To Poop

High Caffeine Content

One of the primary ingredients in pre-workout supplements is caffeine. It is often when the stimulant effects of the pre-workout kicks in you need to head to the toilet. A serving of pre-workout normally contains at least 150mg of caffeine. This is a similar amount to a standard cup of coffee.

Coffee is well-known to make you poop

Research studies suggest that caffeinated coffee causes 60% more bowel movements than decaffeinated coffee. This suggests that caffeine also causes bowel movements.

If you don’t know how much caffeine that your supplement contains per serving, you should definitely check. You should not consume more than 400mg of caffeine in a single day.

caffeine formula

Exceeding the recommended dosage can cause side effects such as insomnia, diarrhea dehydration, increased heart rate and feeling jittery.

Artificial Sweeteners

Sweeteners can be found in many fitness supplements as an alternative to sugar and to improve their flavor. But problems may arise as the body can sometimes find them difficult to digest.

If sweeteners enter the colon in an undigested state, it can be a big task for the bacteria to process it. This creates methane and CO2 which can cause abdominal discomfort.

In one study, several people who used a supplement containing aspartame to lose weight experienced gas and bloating.

Many artificial sweeteners such as sorbitol, sucralose, and aspartame are also used in laxatives.

Consuming a larger volume of sweeteners can mean that this bacteria cannot keep up. This undigested sweetener can cause water absorption into the colon and this results in an unpredictable bowel movement and a visit to the toilet.

Nitric Oxide

If your pre-workout contains nitric oxide, this can also be partly responsible for bowel movements. a research study suggested that nitric oxide could play an important role in patients with constipation.


When performing high intensity exercise, the body generally needs 10% to 20% more magnesium than normal. This helps delay fatigue, reduces muscle cramps and improves mood.


Studies show that consuming additional magnesium before exercise will improve performance. So with these benefits, many health supplement manufacturers add magnesium to their products.

But magnesium is also commonly known to make you poop and is the main ingredient in many laxatives.

It increases the water inside the colon and causes bowel movements. Therefore, if your pre-workout contains magnesium, there’s a good chance that it is contributing to your pooping.


This is a type of sugar that is found in dairy products such as milk. It is also present in some pre-workouts. If you have lactose intolerance, then your body may struggle to digest it.

protein shake

“Protein farts” are common after drinking protein shakes and this is the same. It can also cause flatulence, bloating, and diarrhea.

Does Pre-Workout Make You Fart?

Yes. Caffeine in pre-workout supplements increases the acid levels in the intestines. This stimulates the digestive tract which can lead to excessive gas production and abdominal bloating. This gas finds its way through your stomach and into your mouth as a result of swallowing. The body may also try to expel this excessive gas by farting or burping.

As mentioned earlier, lactose found in some pre-workouts also contributes to this gas and flatulence. Lactose can also make flatulence smell worse than usual.

woman smelling in the gym

Exercise can be another cause of excessive farting. Many exercises cause the intestines to move and release gas. Heavy breathing, as well as gulping water, can cause air to be trapped in the digestive tract which is expelled through the anus.

Does Pre-Workout Make Your Poop Smell?

The lactose present in some pre-workouts can be the main contributor to stinky poop. If you are lactose intolerant, then the body may struggle to digest it. In this case, the undigested lactose stays in the gut and is fermented by bacteria to produce foul-smelling stools and gas.

Can Pre-Workout Give You Diarrhea?

Diarrhea after consuming a pre-workout can be a reaction to some of the ingredients. It may also be a result of not mixing the pre-workout powder with not enough water.

The manufactures directions sometimes mention using a low volume of water. This is sometimes only enough to create a paste. When this is ingested, the body will pull water into the intestines to process it. This water can flood the intestines which then causes diarrhea. The simple solution to this is to drink your pre-workout with an adequate amount of water.

Runners’ diarrhea is a real thing. If you are running after taking a pre-workout, this can also contribute to diarrhea.

Does C4 Pre Workout Make You Poop?

Yes, it can. It contains 150mg of caffeine per serving. This will likely make you head to the bathroom if you haven’t recently been. The effects of C4 last a while, so you can take your time in the loo.

It also contains the sweeteners acesulfame K and sucralose. Sucralose is considered one of the better sweeteners for the bowels, it can still make you need to go.

Final Thoughts

There are many effects of taking pre-workouts on the digestive system and many of them are very common. If you have continuous problems with your pre-workout, it may be a good idea to switch to a type that has a lower amount (or none at all) of the ingredient that may be affecting you.