Does Creatine Cause Diarrhea, Constipation, Cramping?

A user from the Beginner Fitness community on Reddit recently shared their first experience with creatine, describing how a 5g dose of micronized creatine monohydrate left them feeling bloated and gassy.

Wondering if splitting the dose across breakfast, lunch, and dinner might help, they also noted that their sensitive stomach could be a contributing factor.*

This story is not uncommon among new creatine users, raising questions about potential side effects. Does creatine cause digestive issues like diarrhea, constipation, or cramping?

In this article, we dive into the evidence to uncover the truth behind these concerns and explore what you need to know about creatine’s impact on your body.

How Does Creatine Work on the Human Body?

Creatine is a natural compound found in the body that plays a key role in energy production, especially in tissues with high energy demands, such as muscles, the brain, and the heart. It works by increasing levels of phosphocreatine (PCr), a fast-acting energy source the body uses to make ATP (adenosine triphosphate), the primary fuel for cells (Andres et al., 2016).

When energy demand spikes during intense activity, CK helps convert PCr and ADP (a molecule that accepts a phosphate group to form ATP) back into ATP, effectively acting as a temporary energy reservoir. This PCr/CK system supports anaerobic ATP production and enhances performance in explosive movements [3].

As one study notes:

“The theory behind its use is similar to that of carbohydrate loading, because an increased muscle Cr content would conceivably enhance the capacity of the phosphagen energy system, providing greater resistance to fatigue and improving performance.” - (Creatine Supplementation Increases Total Body Water Without Altering Fluid Distribution, 2024) [6].

Creatine monohydrate may help your muscles store more creatine, which the body uses during quick, high-effort movements like sprinting or lifting weights. By supporting the energy system that powers these activities, it could help you feel less fatigued during short bursts of intense exercise.

Creatine may help draw more water into muscle cells, leading to a rise in total body water and a small weight gain, typically around 0.5-1.6 kg [2].

Most of this weight is from water retention, although some evidence suggests creatine may also support protein synthesis. This hydration can aid temperature regulation and reduce the risk of overheating during exercise in hot environments (Dalbo et al., 2008).

Additionally, creatine may help promote muscle growth and recovery by increasing the production of muscle proteins and growth factors such as IGF-I and IGF-II [7]. It also acts as an antioxidant and supports brain health by protecting nerve cells, boosting energy metabolism, reducing mental fatigue, and potentially improving cognitive performance [4].

However, these changes—especially in muscle hydration and metabolism—can affect digestion, fluid balance, and muscle function. As a result, some individuals may experience side effects such as bloating, cramping, or diarrhea when using creatine.

Does Creatine Cause Diarrhea?

Most scientific research shows that creatine monohydrate does not cause diarrhea when taken at the recommended dose [3]. In healthy individuals, controlled studies consistently report no significant digestive issues linked to proper creatine use.

Still, some people report experiencing diarrhea or stomach discomfort after taking creatine. For example, a study by Juhn et al. found that 31% of athletes experienced diarrhea, while another study by V.J. Dalbo reported gastrointestinal symptoms in 16 out of 52 male college athletes [5,7].

However, this doesn’t necessarily mean creatine directly causes diarrhea. These issues may instead stem from factors such as taking too much at once or using it improperly.

One likely explanation is that large single doses—for example, over 5 grams—can overwhelm the digestive system. If the creatine powder isn't fully dissolved in water before consumption, it may draw extra water into the intestines, causing an osmotic effect that leads to loose stools [7].

Moreover, In Francaux’s report, he noted that Vandenberghe et al. observed minor gastrointestinal discomfort in a third of participants (3 out of 9) after three days of combined creatine (0.5 g/kg/day) and caffeine (400 mg/day) supplementation, suggesting a possible interaction that may contribute to digestive issues [7].

You may also read: Does Creatine Cause Hair Loss? User Experiences & Scientific Evidence

For instance, a Reddit user shared that a single 5g dose of micronized creatine left them bloated and gassy. They wondered if splitting the dose into smaller servings throughout the day would help*.

While anecdotal, such firsthand experiences are fairly common and may contribute to the perception that creatine causes digestive problems, especially when dosing or preparation is suboptimal.

Additionally, while anecdotal claims often link creatine supplementation to digestive issues such as stomach pain, nausea, and diarrhea, these reports typically lack strong scientific support.

Although some individuals do experience these symptoms, controlled studies have not consistently shown a direct connection between creatine monohydrate and digestive problems like diarrhea [5,7].

In short, creatine is unlikely to cause diarrhea when taken correctly. But taking too much at once, not dissolving it fully, or combining it with caffeine or other supplements may upset your stomach. If you're sensitive, try smaller doses, mix it well in water, and avoid loading phases.

Does Creatine Cause Constipation?

No evidence suggests creatine monohydrate causes constipation in healthy individuals at any dose. Scientific studies and clinical trials report no such side effect.

Constipation is not documented as a side effect of creatine, but some users speculate it might occur due to broader discussions about digestive issues. On platforms like Reddit, a user in the forum Creatine describes a story of an 18-year-old man who experienced prolonged constipation after starting high-dose creatine supplementation (10-12g per day).

However, controlled studies, including long-term trials with ALS or Parkinson’s patients using 10 g/day, show no gastrointestinal issues like constipation [3].

Does Creatine Cause Cramping?

Creatine monohydrate doesn’t cause muscle cramps in healthy people when taken at the recommended dose. Research shows there’s no proven link between creatine and cramping, and it might even help protect against it.

On forums like Reddit, some users do report cramping while using creatine, but they often attribute it to dehydration or taking too high a dose*. These anecdotal reports add to the confusion.

Interestingly, a study by Greenwood et al. in 2003 suggested that creatine might reduce cramping. In the study, college football players who took creatine for four months had fewer muscle cramps, strains, and heat-related issues compared to those who didn’t take it [5].

The FDA has also noted that reports of cramping can’t be directly linked to creatine without more solid scientific evidence. Although rare cases of mild cramping have been reported, such as in postmenopausal women taking higher doses, these instances are not common and don’t represent the typical experience [2].

Does Creatine Cause Water Retention?

Yes, creatine monohydrate causes water retention, leading to increased body weight (0.7–2.0 kg) and total body water (TBW) [1]. This is a well-documented effect of supplementation.

As mentioned earlier, creatine is an osmotically active substance, meaning it pulls water into muscle cells. This increases both intracellular water (ICW) and total body water (TBW), which in turn causes the body to hold onto more water and gain weight [1,5,6].

This effect usually becomes noticeable within a few days, especially during loading phases where people take 20–25 grams per day for 5–7 days [3,6]. Studies using direct measurement techniques have confirmed that higher levels of creatine in muscle cells lead to greater water retention, which is evenly split between fluid inside and outside the cells.

This finding helps debunk earlier theories that uneven water shifts could cause problems like cramping [6].

Does Creatine Cause Nausea?

Scientific studies show no consistent link to digestive issues like nausea.

Anecdotal reports from users, such as complaints of nausea, stomach discomfort, or vomiting, have fueled the perception that creatine may cause digestive problems [1,2,7].

Nausea is another issue that often stems from improper creatine use or individual sensitivity—topics we've discussed in earlier sections. Some Reddit users have reported feeling nauseous, particularly in the morning, which may indicate that their bodies are not tolerating the supplement well.*

In one case, a person with only one kidney described experiencing persistent nausea, prompting helpful community suggestions such as lowering the dose, switching to creatine gummies, or using pure, additive-free creatine.

Others recommended taking creatine with food or mixing it into warm tea to aid digestion, while also emphasizing the importance of staying well-hydrated to support kidney health.*

While no studies directly confirm nausea as a common side effect, anecdotal reports suggest it may stem from an osmotic load in the gut when creatine is poorly dissolved or taken in high doses [2,7]. For those with health conditions, consulting a professional is advised, as individual responses vary.

Does Creatine Cause Bloating?

Creatine can cause bloating in some users due to water retention in muscle cells, but this is not universal and varies by individual.

Celebrity Nutrition Expert and Fitness Hall of Famer JJ Virgin shared on a podcast that 76% of users may face temporary bloating or digestive issues with creatine monohydrate due to its low 15% absorption rate, but she recommends creatine HCl, which is 99% absorbed, reducing bloating and requiring lower doses.

If creatine monohydrate doesn’t sit well with your body, switching to creatine HCl might be worth considering. Still, individual responses vary—what works well for one person may not be suitable for another.

It’s also worth noting that while creatine HCl shows promise, it hasn’t been studied as extensively as creatine monohydrate, which remains the most thoroughly researched and widely used form among athletes and fitness enthusiasts.

At the end of the day, no supplement can replace the fundamentals. Even the most effective creatine won’t deliver results without proper sleep, regular exercise, a balanced diet, and a commitment to overall health.

Other Creatine Side Effects

Creatine is generally safe for most people, but rare side effects like limb swelling or hair loss have been reported, usually in people taking high doses or those with specific medical conditions. Most healthy users don’t experience any serious problems.

In one study, ALS patients who took 10 grams of creatine per day showed signs of limb swelling, likely due to the water retention effects of creatine [3]. Hair loss has also been reported in a few cases involving very high doses (such as 30 grams per day) in patients at risk for Huntington’s disease.

However, these findings don’t easily apply to healthy adults, since the patients had other health conditions and were on medications that may have played a role [3].

The FDA has received consumer complaints, including rare cases of deep vein thrombosis, but notes that no direct connection to creatine has been confirmed [2].

How to Avoid These Side Effects From Creatine?

To minimize creatine’s side effects—such as bloating, diarrhea, or nausea—stick to the recommended dose of 3–5 grams per day and follow proper usage guidelines. Creatine’s osmotic effect draws water into muscle cells, which can cause digestive discomfort or bloating if not managed correctly [6].

First, always dissolve creatine monohydrate completely in water or juice before drinking it, as undissolved particles may irritate the stomach (Greenwood et al., 2003). Taking it with food can also help improve digestion. Staying well-hydrated is crucial since creatine pulls water into muscles, and low fluid intake may stress the body (Kreider et al., 2017).

Avoid high doses or loading phases (20–25 grams per day), as they can increase water retention and digestive issues. If you're prone to bloating, consider using creatine HCl, which requires smaller doses and may be easier on the stomach (Virgin, podcast).

You can also split your daily Creatine dose into smaller portions throughout the day if you have a sensitive stomach.

Additionally, choosing high-quality creatine from reputable brands can significantly reduce the risk of contaminants or fillers that may worsen side effects. Look for products that are third-party tested for purity and quality.

Finally, consult a doctor before using creatine if you have any health conditions, such as kidney problems. By following these steps, you can enjoy the benefits of creatine while minimizing discomfort.

Conclusion

Creatine monohydrate is a safe and effective supplement, but some users report mild side effects like bloating, diarrhea, or nausea, often linked to water retention or high doses. However, most of these symptoms haven't been confirmed by scientific studies. To reduce discomfort, make sure to fully dissolve creatine in liquid, stay well-hydrated, and consider forms like creatine HCl, which may be easier on the stomach. Not sure if creatine is right for you? Consult a healthcare or fitness professional to find the best fit for your needs.