Can Protein Powder Cause Diarrhea? The Surprising Answer

Our main question is, can protein powder be very dangerous and cause diarrhea? To answer this question first we have to learn more about your gym routine and intake of protein powder.

You’ve been hitting the gym hard and pounding the protein to gain muscle. But lately, something else has been pounding—your stomach.

Those protein shakes and bars you’ve been consuming like crazy seem to be wreaking havoc on your digestive system. You’re running to the bathroom more times than you can count and wondering if all that whey and casein is the culprit.

The short answer is yes, can protein powder cause diarrhea, especially if you’re not used to consuming so much of it? While protein powder does have its benefits when consumed properly, too much of a good thing can definitely lead to unwanted side effects. Before you swear off protein powder altogether, here are some tips to help improve your digestion and find the right balance.

What Is Protein Powder?

Protein powder – you’ve probably seen it at your local supplement store or even in some grocery stores these days. But what exactly is the stuff?

Can protein powder cause diarrhea ? Learn more at Healthy Laws

Protein powder is a powdered form of protein derived from plant or animal sources that people often add to smoothies or mix into other foods and drinks. The most common types are:

•Whey protein – comes from cow’s milk, quickly digested, contains all 9 essential amino acids our body needs.

•Casein protein – also from cow’s milk, digested slowly, contains all essential amino acids.

•Pea protein – from yellow peas, plant-based, contains all essential amino acids but lower in certain amino acids like methionine. Often used by vegans and vegetarians.

•Soy protein – from soybeans, plant-based, contains all essential amino acids but also contains isoflavones which some avoid.

•Hemp protein – from hemp seeds, plant-based, contains all essential amino acids but lower in lysine. Has a strong, nutty flavor.

•Rice protein – from rice, plant-based, low in certain amino acids like lysine, so often combined with pea protein.

The amount of protein per scoop can range from 10 to 30 grams depending on the product and brand. Most people use protein powder to increase their protein intake, build muscle, improve recovery after exercise, and lose fat.

However, some people do experience side effects like diarrhea, bloating or nausea from protein powder. We’ll explore the reasons why in the next section.

The Potential Causes of Protein Powder Diarrhea

Protein powder can be a quick and easy way to boost your protein intake, but it may come with some unpleasant side effects like diarrhea. There are a few possible reasons why your protein shake could be causing digestive distress.


Many protein powders contain artificial sweeteners, thickeners, and other additives that some people don’t tolerate well and can lead to diarrhea. Dairy-based powders in particular contain lactose, which is a common trigger for digestive issues in lactose intolerant individuals.

If you have a sensitivity to any ingredients, switching to a different powder with simpler, more natural ingredients may help.


Consuming too much protein powder at once can overwhelm your digestive system and cause diarrhea. Most people do fine with 1-2 scoops per shake, but any more than that may be too much for your body to handle. Start with a small amount and gradually increase over time as your body adjusts.


Protein powder needs to be mixed with water or milk to form a shake. If you don’t add enough liquid, the powder can dehydrate you and lead to diarrhea. Be sure to mix your powder with at least 8-12 ounces of water or other beverage per scoop. Staying properly hydrated in general will also help promote good digestion and bowel movements.

By determining which ingredient, quantity or hydration issue may be the culprit and making the necessary adjustments, you can likely enjoy your protein powder again without the undesirable watery stools. If problems persist, you may need to try a different powder or speak to your doctor.

Lactose Intolerance and Whey Protein

Many protein powders contain whey protein, which is derived from cow’s milk. If you have lactose intolerance or a dairy allergy, whey protein can potentially cause digestive issues like diarrhea, gas, and bloating. This is because whey still contains lactose, the sugar found in milk that can be hard for some people to digest.

Does that mean you have to avoid whey protein altogether? Not necessarily. There are a few options to try:

  • Look for whey protein isolate or whey protein hydrolysate. These forms have little to no lactose, so they may not trigger symptoms. Whey protein concentrate still contains some lactose, so avoid that.
  • Start with a small amount. Introduce whey protein gradually to give your body time to adjust. A single scoop may be fine, but two or three scoops could overload your system.
  • Choose a non-dairy protein powder. Plant-based options like pea protein, soy protein, pumpkin seed protein or hemp protein are naturally lactose-free. They provide a similar amino acid profile to whey without the digestive distress.
  • Use a digestive enzyme. Supplements like lactase tablets or drops can help improve your body’s ability to break down lactose. Take them just before or along with your whey protein shake.
  • See if you can build up a tolerance. Some research shows that exposing yourself to small amounts of lactose regularly over time may help improve digestion and reduce symptoms. Under medical supervision, you can try slowly increasing your whey protein amount over weeks or months.

The bottom line is that whey protein can cause diarrhea and other issues in people with lactose intolerance, but there are several ways to make it more tolerable or choose a non-dairy alternative. By starting slowly, choosing a lactose-free form of whey, using supplements or switching to plant protein, you may be able to reap the benefits of protein powder without the unwanted side effects.

Too Much Protein in One Serving

If you’re experiencing diarrhea after drinking a protein shake or smoothie, the amount of protein in a single serving could be the culprit. While protein powder is generally safe for most people, consuming too much protein at once can lead to gastrointestinal issues like diarrhea, gas, bloating, and cramps.

Watch Your Portion Sizes

Pay close attention to the serving size listed on your protein powder container and don’t overdo it. Most brands recommend one to two scoops per shake, which typically provides 20 to 30 grams of protein—for some people, this amount in one sitting may be too much for your body to handle comfortably.

Start with a smaller amount, like one scoop or half a scoop, and see how you feel. You can always build up gradually as your body adjusts.

Some signs you may have overdone the protein include:

  • Loose, watery stools within a few hours of drinking your shake.
  • Gas, cramps, or a bloated sensation in your gut.
  • Nausea or indigestion.

If you experience these symptoms regularly after consuming protein powder, cut back to a level your body can tolerate better. You may find that spreading your protein intake over the course of the day in smaller doses is easier on your stomach.

Choose a High-Quality Powder

In some cases, the type or quality of the protein powder itself could contribute to GI issues. Whey protein isolate or plant-based protein powders tend to be easier to digest than cheaper whey protein concentrates. Look for a powder that contains minimal additives, fillers, and artificial sweeteners, which can also irritate your stomach.

Staying properly hydrated, especially when consuming protein powder, can also help reduce diarrhea and other digestive problems. Aim for 6 to 8 glasses of water per day to keep your system running smoothly.

If diarrhea from protein powder persists or is accompanied by severe pain or dehydration, consult your doctor. They may want to test for potential food sensitivities or other underlying issues.

With some experimentation, you can find a protein powder and portion that works for you without the unwanted side effect of diarrhea. Start slowly, choose high-quality powder ingredients, stay hydrated and you’ll be gaining muscle in no time.

Artificial Sweeteners in Protein Powder

Many protein powders contain artificial sweeteners to improve the taste without adding extra sugar. While artificial sweeteners are considered safe in moderation, some studies show they may trigger gastrointestinal issues like diarrhea in large amounts.

Common artificial sweeteners in protein powder

Two of the most popular artificial sweeteners used in protein powders are sucralose (Splenda) and acesulfame potassium (Acesulfame K or Ace-K). These are considered “non-nutritive” sweeteners because they are much sweeter than sugar but have negligible calories. However, some research indicates they may disrupt gut bacteria and the digestive system in high doses.

Consuming a moderate amount of protein powder with artificial sweeteners is typically fine for most people and unlikely to cause diarrhea or other issues. However, if you have a sensitive stomach or frequently consume very large servings of protein powder, the artificial sweeteners could potentially trigger diarrhea or loose stools in some cases. Some signs this may be happening include:

  • Cramping, bloating or gas after consuming the protein powder
  • An urgent need to use the bathroom shortly after drinking a protein shake
  • Watery or loose stools that last more than a couple of days

If you experience these symptoms frequently after drinking protein shakes with artificial sweeteners, it’s a good idea to cut back your serving size or switch to a protein powder with natural sweeteners like stevia extract or monk fruit instead. You can also try slowly reintroducing the same protein powder in small amounts to see if the symptoms return before eliminating it from your diet completely.

In summary, while most people can enjoy protein powder with artificial sweeteners in moderation, be on alert for any unwanted digestive effects. If problems arise, adjust the amount, try a different brand or opt for a naturally-sweetened protein powder. Your tummy will thank you!

Contaminated or Poor Quality Protein Powder

Contaminated or poor quality protein powder could be the culprit behind your diarrhea. Powder that has gone bad or contains harmful bacteria, parasites, heavy metals or other contaminants may negatively impact your gut health and digestion.

Look for signs that your protein powder has gone bad like a foul odor, clumping, or a change in color or texture. If your powder has expired, it’s best to discard it, as bacteria and other microbes can grow rapidly, producing toxins that may cause illness. Consuming contaminated powder can lead to foodborne illness resulting in diarrhea, nausea, vomiting and other symptoms.

Poor manufacturing processes may also lead to contaminated product. Choose a reputable brand that follows good manufacturing practices and proper sanitation. Check if the product has been tested for contaminants like heavy metals. Some plant-based protein powders in particular have been found to contain high amounts of heavy metals like lead and arsenic.

An additional cause of diarrhea could be a food sensitivity or allergy to certain ingredients in your protein powder like dairy (whey or casein), nuts (almond or pea protein), or artificial sweeteners (sucralose or acesulfame potassium).

If you experience bloating, cramps or diarrhea after consuming the powder, you may have an intolerance to one of the ingredients. The only way to determine the culprit is through an elimination diet.

To avoid contaminated or poor quality protein powder and the unwanted side effect of diarrhea, there are a few precautions you can take:

•Choose a reputable brand that follows safe manufacturing practices. Check the product for quality certifications.

•Check the expiration or ‘best by’ date before purchasing. Don’t consume expired product.

•Inspect the powder for any signs it has gone bad before using. If there are any changes in smell, color or texture, discard the powder.

•Start with a small amount of powder and gradually increase to allow your body to adapt. This can help determine if you have a sensitivity to any ingredients.

•Consider a plant-based or whey protein isolate which typically has fewer additives and potential contaminants.

•Stay properly hydrated when consuming protein powder to support digestion and gut health.

Following these tips will help ensure you choose a high-quality, contaminant-free protein powder and allow you to reap the benefits without the undesirable side effect of diarrhea.

How to Prevent Protein Powder Diarrhea

To avoid diarrhea from protein powder, there are a few tips you can follow:

Start with a small amount

When you first start using a protein powder, begin with a small amount, around 1/2 to 1 scoop. This allows your body to get used to it gradually. Suddenly consuming a large amount of protein powder can overwhelm your system and lead to diarrhea or other gastrointestinal issues.

Drink plenty of water

Protein powder needs to be mixed into a liquid, and water is your best choice. Aim for 6-8 ounces of water for every scoop of protein powder. Staying well hydrated will help your body digest the powder properly and reduce the likelihood of diarrhea. Increase your water intake in general when consuming protein powder.

Choose a high-quality powder

Not all protein powders are created equal. Look for a powder from a reputable brand that is made from high-quality
powder ingredients. Whey or casein protein from grass-fed cows is a good option. Plant-based powders made from pea protein or rice protein can also be good choices. Avoid powders with lots of artificial sweeteners, which can irritate your stomach.

Start with a small scoop and build up slowly

Begin with just 1/2 or 1 scoop of protein powder and see how your body tolerates it. If after a few days you have no issues, you can build up to the recommended serving size gradually by adding another 1/2 scoop every couple of days. This will allow your body to adjust slowly to the increased protein intake and minimize the chances of diarrhea.

By starting slowly, drinking plenty of water, choosing a high-quality powder, and gradually building up the amount, you can enjoy the benefits of protein powder without the undesirable side effect of diarrhea.

If you do experience diarrhea, cut back to a smaller amount or stop using the powder for a few days to give your body a break. You may need to try a different brand or type of powder altogether if problems persist.

Tips for Easing Protein Powder-Related Diarrhea

If protein powder is giving you the runs, don’t worry—there are some things you can do to firm things up. Here are a few tips to ease protein powder-related diarrhea:

Start with a lower dose.

The most obvious solution is to cut back on the amount of protein powder you’re consuming. Start with half the recommended serving size and see how you feel. Gradually increase the amount over time as your body adjusts. Your digestive system may just need time to get used to the protein load.

Choose a different type of protein powder.

Whey and casein are the most common types of protein powder, but they don’t agree with everyone. Plant-based protein powders made from pea protein, rice protein or hemp protein may be gentler on your stomach. Or try a beef or egg white protein powder. Switching to a different source of protein can make a big difference.

Stay hydrated and spread out your doses.

Drink plenty of water to keep your stool soft and avoid dehydration. Also, instead of consuming your entire protein shake at once, split it up into two or three smaller servings spread throughout the day. This makes the amount of protein powder you’re taking in at one time more digestible.

Add probiotics.

Probiotics or “good bacteria” can help improve gut health and digestion. Either switch to a protein powder that already contains probiotics, or take a probiotic supplement. The natural bacteria cultures may help your gut better break down the ingredients in protein powder.

Talk to your doctor about digestive enzymes or medications.

In some cases, diarrhea from protein powder may be related to an underlying digestive issue like lactose intolerance or irritable bowel syndrome. Your doctor may recommend over-the-counter digestive enzymes, or possibly prescription medication to ease your symptoms. They can also determine if protein powder is right for your needs and provide guidance on alternatives.

The bottom line is that protein powder diarrhea usually isn’t serious and often improves with simple solutions. Be patient, make adjustments to the amount or type of protein powder, stay hydrated and consider supplements or probiotics. If problems persist for more than a few days, consult your doctor. They may be able to get to the bottom of what’s causing your digestive distress.

FAQ – Answering Common Questions About Protein Powder and Diarrhea

Protein powder supplements are popular among athletes and bodybuilders looking to boost their protein intake. However, some people experience gastrointestinal issues like diarrhea, gas or bloating after consuming protein powder. Here are the answers to some common questions about protein powder and diarrhea.

Can protein powder cause diarrhea?

Yes, protein powder can potentially cause diarrhea or loose stools in some people. There are a few reasons why:

  • Consuming too much protein powder at once can overload your digestive system and cause diarrhea. Start with a small amount, like one scoop, and gradually increase the amount over time as your body adjusts.
  • Whey protein in particular contains lactose, a milk sugar that some people have difficulty digesting. If you’re lactose intolerant, a whey protein isolate or a plant-based protein powder may be better options.
  • Artificial sweeteners like sucralose or acesulfame potassium are used in some protein powders and can cause gastrointestinal issues in sensitive individuals. Choose a protein powder with natural sweeteners like stevia instead.
  • Bacterial contamination is also possible if the protein powder was not manufactured or handled properly. Check reviews and only buy from reputable brands to minimize the risk of contaminated product.

Is it normal to have diarrhea after eating protein?

Occasional loose stools or diarrhea after consuming protein powder is usually not a cause for concern and will often resolve on its own. However, if you frequently experience severe or persistent diarrhea, gas, cramping or other issues after using protein powder, you may have an intolerance or sensitivity to an ingredient. It’s best to stop using that particular protein powder and consult your doctor.

Can protein powder cause gas and diarrhea?

Yes, protein powder can cause excess gas, bloating, and diarrhea in some cases. The high amount of protein and certain ingredients like artificial sweeteners or lactose can make it difficult for the gut to break down and may lead to gastrointestinal problems.

Be sure to start with a small amount of protein powder and see how your body tolerates it. Switching to a different type of protein powder or a plant-based option may also help. If problems persist, it’s best to stop using protein powder and talk to your doctor.


So there you have it. While protein powder can be a convenient way to boost your protein intake, it may come with some unwanted side effects like diarrhea, gas, and bloating for some people. The good news is these symptoms are usually temporary as your body adjusts.

Still, it’s a good idea to start with a small amount, choose a high-quality powder, stay hydrated, and give your body time to adapt. If problems persist, it may be a sign you have an underlying condition or intolerance. Talk to your doctor, especially if you experience severe or prolonged symptoms. Otherwise, keep calm and protein on—your gains will be worth it!

Follow Me

Leave a Comment