Why Does Protein Powder Make My Stomach Hurt?

📌 Overview and Key Takeaways

Why does protein powder make my stomach hurt?

Discover how to supplement your protein intake without upsetting your stomach.

Last Updated
Jan 7, 2026

Author and Medical Reviewer

Written by Kayla Kamen, MS, RD

Kayla Kamen is a Registered Dietitian with a MS in Nutrition.

Medically reviewed by Jennifer Fossett, PA-C

Jennifer Fossett is a Physician Assistant with a BA in Nutritional Sciences.

Protein Powder and Stomach Pain

Can Protein Powder Make My Stomach Hurt?

If your protein powder hurts your stomach, you are not alone.

Many people report that their protein powder causes stomach pain.

I myself have wondered why protein powder hurts my stomach, and it was not until I started reading ingredient lists that it made sense to me.

Many, if not most, protein powders can upset your stomach because they are ultra-processed and full of added junk.

In other words, the majority of protein powders look nothing like real food, which can lead to painful digestive issues.

Keep in mind that stomach pain can range from mild to severe, and last for a few minutes to a few hours.

Seek professional medical help if you have pain so severe that you cannot move without causing more pain.

What Should I Do if My Protein Powder Hurts My Stomach?

If your protein powder is causing stomach pain, here are a few steps you can take to address the issue:

1. Switch brands: Not all protein powders are created equal. Different brands use different ingredients, so trying a different brand might solve the problem.
2. Adjust the serving size: It is possible that you are consuming too much protein powder at once, which can overwhelm your digestive system. Try reducing the serving size to see if that helps reduce side effects.
3. Change the timing: Some people find that consuming protein powder before or after a meal, rather than on an empty stomach, reduces digestive issues. Experiment with different timing to see what works best for you.
4. Mix it with different liquids: Sometimes, the type of liquid you mix your protein powder with can affect digestion. Try mixing it with water, milk, a milk substitute, or another liquid to see if one works better.
5. Check the ingredients: Many, if not most, protein powders contain one or more ingredients that are hard to digest. As a rule of thumb, look for a short list of simple ingredients.

By listening to your body and following the steps above, you can find a protein powder that not only meets your nutritional needs, but also agrees with your digestive system.

Why Does Protein Powder Make My Stomach Hurt?

Unless you have a food allergy or sensitivity to one of the ingredients in your protein powder, one of the following is likely to blame for your stomach pain:

🚫 Avoid Food Additives

Emulsifiers, thickeners, and other additives can upset your stomach because they are hard to digest.

Foods that are hard to break down and absorb feed your gut bacteria, which release gas as they eat.

And too much intestinal gas can cause bloating, stomach pain, and even constipation.

Regularly eating certain food additives can also alter the composition of your gut microbiome (North Clin Istanb, 2019).

Over time, this can lead to gut dysbiosis (Microorganisms, 2022), or an imbalance in gut bacteria, which has been linked to a number of painful digestive issues (JGH Open, 2021).

⚠️ Here is a list of the most common food additives in protein supplements:

• acacia fiber
• acacia gum
• acesulfame potassium
• artificial flavors
• ascorbic acid
• aspartame
• calcium carbonate
• carrageenan
• cellulose gum
• dextrin
• dicalcium phosphate
• dipotassium phosphate
• erythritol
• gellan gum
• guar gum
• gum arabic
• inulin
• locust bean gum
• maltitol
• maltodextrin
• mono- and diglycerides
• ‘natural’ flavors
• rice bran extract
• rice dextrin
• rice hulls
• rosemary extract
• silica
• silicon dioxide
• sodium alginate
• soluble corn fiber
• sorbitol
• soy lecithin
• sucralose
• sunflower lecithin
• tocopherols
• tricalcium phosphate
• xanthan gum
• xylitol
• zinc oxide

Note that this list includes several artificial sweeteners.

Artificial sweeteners like sucralose and acesulfame potassium are among the worst ingredients for your gut microbiome (Nature, 2014).

They both reduce microbial diversity and promote the growth of potentially pathogenic bacteria.

Also note that as a rule of thumb, if you cannot find it in nature or make it at home, it is probably a food additive.

🚫 Avoid Dairy-Based Proteins

Dairy-based proteins like whey and casein, although not an issue for everyone, can cause digestive issues.

This is usually because they contain lactose, a sugar many individuals with sensitive stomachs cannot fully digest.

But you might be sensitive to dairy-based proteins even if you are not lactose intolerant.

This is particularly true for casein protein, which forms a gel-like substance in your stomach that slows down digestion.

🚫 Avoid Protein Concentrates and Isolates

If you have a sensitive stomach, you might also want to avoid ultra-processed protein concentrates and isolates.

Most protein supplements are made from one or both of these ultra-processed protein sources, which have been mechanically and/or chemically stripped of everything but the protein.

This includes the enzymes, fiber, and other natural digestive aids that help your gut break them down.

You therefore do not digest them in the same way that you do whole foods, which could affect your gut health.

Studies show that regularly eating protein concentrates and isolates might disrupt your gut microbiome (Nutrients, 2018) and cause the formation of toxic byproducts in your gut (Mol Nutr Food Res, 2024).

Individuals with pre-existing digestive issues should thus look for protein supplements made from whole food protein sources like egg whites and almonds, which are easier to digest and absorb.

Order Samples to see for yourself.

Sources

1. Northern Clinics of Istanbul (North Clin Istanb). Food additives and microbiota. 2019.
2. Microorganisms (Microorganisms). Gut Microbiota Dysbiosis: Triggers, Consequences, Diagnostic and Therapeutic Options. 2022.
3. JGH Open: An Open Access Journal of Gastroenterology and Hepatology (JGH Open). Gut microbiota dysbiosis in functional gastrointestinal disorders: Underpinning the symptoms and pathophysiology. 2021.
4. Nature (Nature). Artificial sweeteners induce glucose intolerance by altering the gut microbiota.. 2014.
5. Nutrients (Nutrients). Effect of a Protein Supplement on the Gut Microbiota of Endurance Athletes: A Randomized, Controlled, Double-Blind Pilot Study. 2018.
6. Molecular nutrition & food research (Mol Nutr Food Res). In Vitro Fermentation of Animal and Plant Protein Isolates by the Human Gut Microbiota Under High and Low Carbohydrate Conditions.. 2024.

Editorial Guidelines

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This article was written by a Registered Dietitian and reviewed by a Physician Assistant. We rely on peer-reviewed research and trusted medical sources, and regularly update our content to ensure accuracy and clarity.