Why Does a Pre-Workout Make Me Want to Poop?

When in your veins, the effect of pre-workout is similar to that of cocaine. There is a wide array of variations of the white stuff around the world and at the disposal of fitness freaks. However, they often provide you with some energy boost and offer your muscles a great pump. This leaves you with more incredible confidence about your exercise results as you appreciate yourself in the mirror.

Nonetheless, pre-workout users have reported an issue with the product; it makes you dread squats as you are likely to get somewhat leaky once you take it. We are talking about poop and not pee. An excellent workout session could quickly be curtailed by fecal explosion – the last thing you wish to happen to you as you struggle to squeeze in an extra rep.

A good explanation for why your stomach might appear to clash with pre-workout is that the product is not particularly “natural.” But this is quite the norm with most products we find on the shelves nowadays.

Artificial sweeteners constitute a bulk of the composition of most pre-workouts. If you have been displeased with too many sugar-free gummy bears, you are probably familiar with the sort of damage such fake sweeteners can cause on the bowels. This article looks at components of pre-workout and the possible effect of their interaction with colon walls.

A scoop of pre workout supplement

Pre-workouts & Coffee

Caffeine is the main active ingredient of any pre-workout, which is primarily a psychoactive stimulant. It gives us the necessary mental energy boost before the workout.

Coffee however is a socially acceptable addiction, one or two cups daily won’t do much harm. Research shows that caffeine makes the colon more active, causing a feeling of wanting to poop.

Depending on your serving and the product that you are using, even a scoop of most pre-workout supplements available in the market more often than not contains much more than 100 mg of caffeine.

Most companies suggest 2 scoops which sometimes amounts to over 400 mg of caffeine per recommended serving.

It’s wise to check out the labels on your pre-workout and understand how much caffeine you’re taking as per the recommendation of your trainer.

Pre-workouts & Bowel Movements

Bowel movements are managed by the colon, in the presence of many useful bacteria and water. In a healthy adult, bowels depend on the diet i.e. the food, supplement, and


It is common to find caffeine in pre-workout supplements since it is associated with various performance enhancement advantages. Such benefits include interaction with your nervous system to foster enhanced alertness and focus. It also has the effect of boosting your energy levels. 

The presence of caffeine in various pre-workout is identical to the caffeine content in energy drinks or caffeinated coffee. It has the effect of increasing blood pressure and leads to heart palpitations when taken in excessive amounts.

Once you take pre-workout supplements that have caffeine, it leads to the urge of the stomach to excrete the excess. In addition, it triggers gut motility. The implication is that it can considerably enhance muscle contraction responsible for propelling your stomach contents to the colon and the small intestines. 

Therefore, this, together with your engagement in physical activity, can stimulate you. The pre-workout, however, gives you the urge to have bowel activity. In addition, consuming an enormous amount can lead to dehydration due to watery stool and diarrhea. The caffeine content can also increase your urine production, despite the content being available in even the best pre-workout supplements.

Artificial Sweeteners

Artificial sweeteners are substitutes for synthetic sugar. Though it has a tag of ‘artificial,’ you can source these sweeteners from organic substances, including sugar or herbs. Though not every pre-workout supplement has artificial sweeteners, the majority do, which are usually not known to cause harmful effects on bowel movements.

Nonetheless, the impact of artificial sweeteners depends on how much you use in every serving and how many servings you have. In addition, it might not be among the best healthy lifestyle practices because it is often sweeter than refined sugar.

Supplements that use artificial sweeteners can lead to an enhanced body weight similar to other sugary beverages. However, the bacteria in your gut struggle to break artificial sweeteners down, and therefore its digestion takes a long time. Consequently, this leads to the production of carbon dioxide and methane, hence digestive discomfort.

In the undigested state, the sweetener will absorb water, leading to water retention through osmosis—the harmful effects on your body of this happening range from bloating to the urge for a bowel movement.

It is crucial that you only ingest the recommended dosage if you experience any underlying digestive issues or health complications. This helps in preventing more bowel movements and emergency trips to the washroom.

Some pre-workouts may contain artificial sweeteners referred to as sugar alcohols to act as a flavoring. Though they might be zero-calorie additives, they are not absorbed well in your gut and could lead to diarrhea in individuals.


pre workout and bowel movement



Various pre-workout supplements may contain lactose, which some people may be unable to digest properly. Suppose you ingest pre-workout supplements having lactose, and you are a lactose intolerant individual. In that case, you will likely experience stomach issues like irregular bowel movements and sounds or stomach upset.

Lactose intolerant individuals cannot completely digest lactose (the sugar in milk). As a result, you will experience stomach issues such as gas, bloating, and diarrhea shortly after drinking or eating dairy products like cheese and milk.

Though the extra energy might be necessary, avoid taking high doses at all costs. In such a case of lactose intolerance, avoid taking even small doses of pre-workout supplements that have lactose.


A minute amount of magnesium in a pre-workout supplement will help stimulate and strengthen your body. Magnesium employs an osmotic effect in drawing water into your intestines. Additionally, it is important to associate nitric oxide with heart rhythm, muscle function, immune system, and blood pressure.

Magnesium is an osmotic laxative increases water in your bowel, hence gut motility stimulation. This excess water getting into your intestines also softens and increases your stool size hence the urge for a bowel movement.

Vitamin C

It is common to find large vitamin C amounts in various pre-workout supplements. Scientists have shown that this vitamin could lead to laxative effects. However, this is about large doses of about 2,000mg daily. Comparatively, pre-workout supplements like C4 has only 250mg of the vitamin. Therefore, unless you have extreme sensitivity to the vitamin, it should not have any harmful effects.

Vitamin B12

Pre-workout supplements may also contain vitamin B12. B-complex vitamins, vitamin B3 included, are famous for stimulating muscle contractions within the digestive tract and giving you the urge to visit the washroom. Therefore, if you experience such a stomach issue, you should confirm with the supplement label to ensure the vitamin B12 levels are not high.


You will likely find yohimbine as an extract in various fat-burning and pre-workout supplements. Though it might be an efficient stimulant, it could also trigger stomach upset and other negative effects. In addition, taking yohimbine while your stomach is empty puts you at a greater risk of “emergency evacuation.” Therefore, avoiding pre-workouts containing the compound is recommended if you work out on an empty stomach.


Unless you are ‘dry scooping’ you have to mix pre-workout supplements with water. And by drinking water, you are guaranteed to get the digestive system up and roaring more early in the morning. You can work around this by taking the pre-workout with reduced water – just enough water to dissolve the protein powder. However, you should ensure you drink a lot of water over the day. To make up for the increased water needs of your body – sweat excreted during workouts needs to be replaced by drinking more water to prevent dehydration.

How Long Does Pre-Workout Last?


Pre-workout exercise

Other factors affecting pre-workout poops

When and how you take pre-workout supplements could determine whether you get an upset stomach.


The small plastic scoop you find inside the pre-workout container is meant to dictate the serving. However, full scoops are not the proper dosages for proper bowel movements for all individuals. If you experience potential side effects such as a constant urge to use the bathroom or jitters, consider reducing the serving to half scoops. When the symptoms reduce, you can increase the dose gradually if necessary.


It is okay to take pre-workout supplements shortly before beginning your exercises. However, whether you exercise in the evening or morning can have varying effects after taking it. This means you will be less prone to experiencing negative effects if you take it early in the day. 

The reaction to pre-workouts can vary from person to person. Analysis shows that though one person might ingest caffeine and experience headaches, unexpected bowel movements, and heightened blood pressure, a different person might not. Know how your body reacts to pre-workout and adjust the dosage appropriately.


Pre-workout supplements are essential for many people as they help you navigate through workout sessions. They are particularly important for high-intensity exercises that usually lead to muscle fatigue. A pre-workout supplement, like a cup of coffee, can also help mental focus through interaction with your nervous system and brain and curb weight gain. Nonetheless, we recommend you use these supplements responsibly. Where applicable, seek advice from qualified trainers.

We hope you enjoyed reading the article. Do put in your comments below and let us know how you liked it.


About Gaurav Dhir

Gaurav Dhir, B. Tech, PGDCM is an engineer and MBA by training. A fitness aficionado, Gaurav follows a strict diet and exercise regimen to keep himself vigorously active. He loves playing sports and being outdoors. Gaurav is responsible for the health and wellness of 4 generations including his son, elderly parents and very elderly grandparents.