Can pre-workout make you need to poop?

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

A typical pre-workout will contain a number of ingredients such as creatine, artificial sweeteners, beta-alanine and BCAAs. Many of these ingredients have the potential to cause unpredictable bowel movements.

A healthy diet consists of food, water, and often supplements. These all contribute to the body’s bowel movements. However, adding some ingredients that are found in pre-workouts 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 common that when the stimulant effects of the pre-workout kick in, you need to head to the toilet. A serving of pre-workout normally contains at least 150mg of caffeine which is a similar amount to a standard cup of coffee.

It is well-known that coffee can make you poop.

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

In fact, many stimulants are known to cause a bloated stomach or other digestive issues.

If you don’t know how much caffeine your supplement contains per serving, you should definitely check the label. You should also 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, an increased heart rate and blood pressure, and feeling jittery.

Here are some pre-workouts with a low caffeine content:

Pre-workout Caffeine Content
Myprotein The Pump 0mg
Transparent Labs STIM-FREE 0mg
Pump Surge stim-free 0mg
Genius Pre 0mg
Pre Lab Pro 80mg
Powher 100mg
Cellucor C4 Sport 135mg

Artificial Sweeteners

Sweeteners can be found in many fitness supplements as an alternative to sugar and are also added to improve their flavor. But problems may arise because 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 in the gut to process them. This creates methane and CO2 which can lead to abdominal discomfort.

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

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

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

Here are some pre-workouts without artificial sweeteners:

Pre-workout Sweetener content
Pre Lab Pro No sucralose
Organic Muscle No artificial flavors or sweeteners added
Naked Energy No artificial sweeteners

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 be useful when treating people with constipation.


When performing high-intensity exercise, the body generally needs 10% to 20% more magnesium than is normally required. This magnesium helps to delay fatigue, reduce muscle cramps and improve mood.


Studies show that consuming additional magnesium before exercise can improve performance. Many health supplement manufacturers also add magnesium to their products for these benefits.

But magnesium is also commonly known to make you poop and it 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-workout supplements. 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.


L-Citrulline relaxes the blood vessels to improve blood flow during your workout. This helps your body to remove urine.

So while it does not cause defecation, it may make you need to go to the bathroom anyway.

Sodium Bicarbonate

Sodium bicarbonate, also known as baking soda, is another ingredient that improves workout performance and is found in pre-workouts.

But it is also a commonly used home remedy for constipation relief. So be prepared to head to the toilet if your supplement contains it in significant amounts.

Does Pre-Workout Make You Fart?

Yes. Caffeine in pre-workout supplements can increase the acid levels in the intestines. This stimulates the digestive tract which can lead to excessive gas production and abdominal bloating. The body may try to expel this excessive gas by farting or belching.

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 eventually expelled through the anus.

Alternative Supplements That Won’t Make You Poop

There are some supplements that can do a similar job to a full-blown caffeine-filled pre-workout without making you need the toilet so much. These make use of alternate ingredients but these ingredients can also be more expensive meaning a higher cost to the consumer.

Some alternatives are:

  • Genius Pre-Workout Powder – Contains Stevia, a natural sweetener and is also caffeine-free.
  • Type Zero Pre-Workout Supplement – Caffeine-free and sweetened with Stevia.

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-Workouts Give You Diarrhea?

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

The manufacturer’s instructions can sometimes mention using a low volume of water than is ideal. This is sometimes only enough to create a thick liquid. When this is ingested, the body will pull water into the intestines to process it. This water can flood the gut which then causes diarrhea. The simple solution to this is to drink your pre-workout with an adequate amount of water.

Runner’s diarrhea is also 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 may need to 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 but 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.