If you're a gym rat, you've probably tried every single supplement under the sun. One of the most popular supplements is pre-workout. Pre-workout is meant to give you the extra boost needed to power through your workouts. 

However, like most things in life, pre-workouts have side effects. One of the most infamous side effects of pre-workout is the sudden need to run to the bathroom. 

Not everyone will experience this, but many people that take pre-workout report needing to relieve their bowels shortly after. 

So, does pre workout make you poop, or is it just a coincidence? Let's take a look. 

A pre-workout can increase energy levels, improve exercise performance, and stimulate muscle growth.

The ingredients and effects of pre-workout supplements vary by product, but most products use ingredients like caffeine to boost energy or creatine to help increase muscle mass. 

Some of these ingredients might make you have to poop. 

1. Artificial Sweeteners 

Artificial sweeteners are used in many supplements as a low-calorie alternative to sugar. But these sweeteners are often difficult to digest and absorb. 

When undigested sweetener makes it to your colon, the bacteria have a hard time fermenting it. This produces CO2 and methane that can lead to abdominal discomfort. 

But when you consume a lot of artificial sweeteners, the bacteria in the colon will struggle to keep up with demand.

When this happens, undigested sweetener absorbs water into the colon, resulting in an emergency trip to the gym bathroom. 

2. Vitamin C  

The most popular pre-workout supplements also contain large amounts of vitamin C. While vitamin C has some pretty amazing benefits, scientific reviews suggest it can also have a laxative effect.[1]

However, these studies refer to mega doses of 2,000 mg or more daily. That's a lot of Vitamin C. Your average pre-workout supplement will contain 250 mg of vitamin C.

That means you'd have to take enough pre-workout to launch you to the moon to ingest that much vitamin C. So unless you're overly sensitive to this vitamin, you should be fine.

Man Holding Vitamin C Tablet

3. Vitamin B12  

Many pre-workout blends also contain vitamin B12. Although they serve their purpose, B-complex vitamins are known to stimulate muscle contraction in the digestive system.

Therefore, these vitamins can give you the sensation of needing to go without actually needing to go.  

If you're experiencing this issue in the middle of your workouts, check your supplement label for high levels of B12 or other B vitamins.

4. Magnesium  

Many pre-workout mixes include small amounts of magnesium to strengthen and stimulate the body. 

Magnesium draws water into the intestines using an osmotic effect. It's also instrumental in interacting with nitric oxide in muscle function, heart rhythm, blood pressure, and immune system functioning. 

This causes water to increase within the bowel, resulting in the arousal of gut motility. The excess water also doubles the stool size and softens it. When this occurs, you could develop the urge for bowel movements during your squats. 

5. Yohimbine  

Yohimbine is an extract often found in pre-workouts and popular fat-burning supplements. Yohimbine is an effective stimulant, but it is known to cause an upset stomach and other adverse effects.[2]

If you aren't careful, taking a pre-workout heavy in yohimbine on an empty stomach can result in "emergency evacuation." So if you prefer to workout in a fasted state, it's in your best interest to avoid all pre-workouts containing this compound. 

Read Also - Why Does Pre-Workout Make You Itch?

6. Caffeine 

The first ingredient people look for is how much caffeine is in pre workout. Almost all pre-workouts have high caffeine content. 

Typical pre-workout powders contain anywhere from 150mg of caffeine per serving, all the way up to 400mg+ of caffeine per serving. A regular cup of coffee contains 80 to 150 mg of caffeine. 

Caffeine has been well documented to give you the urge to poop. And this effect can occur within just 10-15 minutes of consumption.

Therefore, the high doses of caffeine in pre-workout supplements could intensify the urge to poop, so plan accordingly. 

7. Lactose 

Some pre-workout supplements even contain lactose, a sugar found in milk. Unfortunately, many people cannot properly digest lactose, so it's a vital ingredient to look out for. 

If you are lactose intolerant and consume a pre-workout with lactose, you will likely experience loose stools and irregular bowel movements (and sounds). 

Even if you need more energy, never take high doses of lactose. Anyone with lactose intolerance should avoid having even a tiny amount of any pre-workout supplement containing lactose. 

man feeling sick after taking pre-workout

Other Factors Associated With Pre-Workouts & Digestion

Now that we know about the ingredients in pre-workout, we can discuss the other factors that could affect your bowel movements.

It turns out how and when you take your pre-workout supplements can also affect how often you visit your gym's locker room.


Each pre-workout powder has a small plastic scoop that dictates the serving size. However, that scoop isn't the correct dosage for everyone. If you frequently have to run to the bathroom after taking your pre-workout, you are maybe taking too much pre-workout. 

Fitness website Total Shape recommends so try scaling back to half of a scoop and gradually increasing your intake from there.

If the symptoms subside, you can gradually increase your dose if necessary. If they don't, check the ingredients list to see what could be affecting your stomach. 

Learn More - Is It Bad to Take Pre Workout Everyday?


You should take your pre-workout shortly before exercising. However, working out in the morning or evening could result in different effects after you take it. 

Most people are less likely to experience undesirable side effects if they exercise and take pre-workout later in the day. 

Related Article - How Long Does Pre-Workout Last?

Empty Stomach 

How much food you have in your stomach will also affect how you react to pre-workout. Taking pre-workout on empty stomach, you are more likely to experience immediate poops or digestive discomfort. 

If you experience these symptoms, you are better off taking your supplement with a healthy pre-workout meal.

Woman feeling sick touching her tummy

How to Avoid Pre-Workout Poops?

Avoiding pre-workout poops before an intense workout session may sound hard, or outright impossible, but a few changes to your lifestyle and decision-making could make a massive difference.

For instance:

Choose the Right Pre-Workout Ingredients

Most pre-workout supplements contain a mix of ingredients designed to enhance your performance. 

However, some of the above-discussed pre-workout ingredients can be hard on the stomach (artificial sweeteners, vitamins, stimulants) and may lead to an unexpected bowel movement.

So, do your research and opt for a clean pre-workout powder that aligns well with your digestive system.

Limit Intake of Stimulants

Stimulants, a common component in pre-workout supplements, can stimulate not only the brain and nervous system but also the bowels. 

If your pre-workout supplement makes you rush to the bathroom, consider checking its caffeine content or other stimulants. Look for milder alternatives, or take half a scoop to reduce the chance of pre-workout poops.

Manage Stress Levels

Stress can have a profound impact on digestion and bowel regularity, which could offset the unwanted side-effects of a pre-workout drink. 

Adopting relaxation techniques such as deep breathing, meditation, yoga, or even short walks can alleviate stress and promote a more predictable digestive pattern.

Eat a Healthy Diet

What you consume on a daily basis can play a significant role in how your body reacts to supplements. 

A balanced diet rich in fiber can help regulate bowel movements and decrease the likelihood of experiencing pre-workout poops. Avoiding greasy or overly processed foods before workouts can help, too.

Stay Hydrated

Adequate hydration is one of the best ways to ensure proper bowel movement. If you’re dehydrated, the pre-workout makes the body work harder to process caffeine and other pre workout ingredients.

So, ensure you drink enough water throughout the day, especially if you’re using a powerful pre-workout supplement.

Is There A Pre-Workout Supplement That Won’t Make You Poop?

If you struggle to stay off the toilet after taking a pre-workout, you likely need to find one with clean, natural ingredients.

For many people, caffeine is the main culprit for the urge to poop. Luckily, finding a good pre-workout without caffeine is entirely possible. Just a few caffeine-free pre-workouts are: 

The other main culprit of the pre-workout diarrhea is artificial sweeteners. Fortunately, there are also natural pre-workouts free of artificial sweeteners. Some of the best pre-workout supplements and our favorites are: 

Common Pre-Workout & Bowel Questions

Can you take a pre-workout on an empty stomach? 

Most pre-workouts are formulated so you can take them on an empty stomach without any issues or side effects. However, as we mentioned above, some people may need to rush to the bathroom after taking a pre-workout on an empty stomach. 

What are the long-term side effects of pre-workout? 

As far as long-term side effects are concerned, it will largely depend on the ingredients and dosages in your pre-workout. A good pre-workout in proper doses is an excellent option for an energy boost. But if they aren't used correctly, they can come with many side effects. It can cause vomiting, jitters, cramps, high blood pressure, and in rare cases, even cardiac arrest. 

Can you drink pre-workout every day? 

Pre-workouts are primarily considered safe, but taking them daily might not be a good idea. If you use them every day for an extended period, side effects may include insomnia, jittery/tingling feelings, or long-term heart problems. 

Does creatine affect poop? 

Many people have reported creatine causing gastrointestinal discomfort, pain, and unusual bowel movements. Certain doses of creatine or different mixes may cause these side effects. Medications you're taking can also interact with it. 


Although pre-workouts will affect everyone differently, some people need to relieve their bowels shortly after taking one. 

Fortunately, there are things you can do to avoid this problem. Finding a natural pre-workout and playing with your dosages and timing can help you get through your workout without having to poop. 


1. http://irep.iium.edu.my/1705/1/fin170.pdf

2. https://pubmed.ncbi.nlm.nih.gov/20442348/

Miloš Lepotic

Miloš Lepotic

Miloš loves three things - science, sports, and simplicity. So, what do you get when you put the three together? A no-BS guy that's all about efficient workouts and research-backed supplements. But he also thinks LeBron's the greatest ever, so...