Why Do Protein Shakes Make Me Nauseous?

By Matt Smith

Published: April 8, 2025

Have you ever felt nauseous after drinking protein shakes? If so, you may be wondering why do protein shakes make me nauseous?

This article will take a quick look at some common causes of nausea in relation to protein powder and help you to avoid nausea in the future.

There are several reasons why your protein shake may be making you nauseous, but the first thing to consider is whether it is the protein shake that is causing your nausea in the first place.

You May Be Feeling Nausea for Another Reason

Don’t worry! We will be looking at all of the possible reasons why protein supplements may cause nausea, but it is a good idea to first ascertain whether it actually is the protein shake.

Nausea has many causes. For example, your nausea could be the result of:

Dehydration
Motion sickness
Viruses
Medication
Migraines
Pregnancy
Inner ear disorders

These are just a few of the hundreds of potential causes of nausea, so if you are feeling sick, you should first consider all of the causes.

Now that we’ve got that covered let’s look at some reasons why you may be feeling nauseated after consuming protein powders.

You May Not Be Able to Tolerate Whey Protein

Is your protein shake made from whey? If so, you may be allergic.

Many people consume whey protein shakes (or a whey protein isolate) without realising that whey is a dairy product and therefore contains lactose.

If you have a lactose intolerance, then you may experience nausea, stomach pain, and a number of other symptoms when you drink a whey protein shake.

Even those with no dairy allergies may struggle with the large amounts of dairy that consuming whey protein shakes can produce.

Anyone who has drunk a large glass of milk very fast can testify to its ability to make you sick.

Lactose Intolerance or Allergy to Milk?

You may not be lactose intolerant, but you could still have a milk allergy, which is a more serious condition that is caused by an allergic reaction to milk protein.

As you can imagine, whey isolate and whey protein are particularly dangerous.

Symptoms can range from stomach aches and issues with your digestive system to hayfever-like symptoms, eczema, or severe reactions such as swelling of the throat, coughing, wheezing, or anaphylaxis.

Of course, sufferers of milk allergies are very unlikely to make the mistake of drinking a whey protein shake.

As they would know where whey protein comes from. But those with mild symptoms who don’t know much about supplements could easily be confused into drinking a whey protein shake.

If you have a lactose intolerance or a milk allergy, then you can try one of the many protein powders that are free from dairy.

Lactose intolerance shouldn’t have to affect your protein consumption now that there are a number of vegan protein powder options.

Your Protein Shake May Dehydrate You

Dehydration is a well-established cause of nausea, and in certain conditions, your protein supplement may be causing mild dehydration.

This is only going to be an issue for people whose protein intake is excessive or for people who have known kidney issues.

When you consume a lot of protein, your kidneys need to work hard to remove nitrogen from your body. This can cause mild dehydration, which can lead to a number of symptoms, one of which is nausea.

Chances are, your protein intake is nowhere near big enough to cause this issue unless you are a bodybuilder or power athlete trying to build muscle.

You May Not Be Able to Handle Artificial Sweeteners in Protein Powder

Many people can consume artificial sweeteners or sugar alcohols without suffering any ill effects, but there is a growing number of people who ARE affected by certain artificial sweeteners and sugar alternatives.

Artificial Sweetener/Sugar Alternatives:

Sucralose
Aspartame
Stevia
Sugar alcohols
Acesulfame potassium

There is a lot of evidence that sugar alcohols cannot be digested properly by digestive enzymes in your small intestine.

Instead, they are sent to the gut, where your gut bacteria breaks them down. This can lead to nausea and stomach upset.

Sucralose is an artificial sweetener that has repeatedly been shown to affect your digestive system, and it is a very common protein supplement ingredient.

If your protein powder contains (arguably) harmful additives such as this, then you may experience bloating, diarrhea, gas, and nausea.

You May Be Drinking Your Protein Shake Too Fast

Foods and drinks that are low in fibre, carbohydrates, and healthy fats tend to be digested very quickly. Protein shakes, which are liquid, are digested even faster than that.

This can cause issues with digestive enzymes in your digestive system and can lead to nausea, bloating, and an upset stomach.

Drinking fast can exacerbate this issue and is one of the most common causes of nausea in relation to protein powders.

The trick is to drink your protein slowly. This gives your body a little more time to digest your protein supplement and can help to prevent nausea.

Alternatively, you can consume drinks with a balanced mix of protein, carbohydrates, and fats.

You May Be Using Protein Shakes Incorrectly

Protein powders were designed to help people increase their protein intake each day. They are made up of almost 100% protein and have very little carbohydrates, almost no fats, and no fibre.

You should be using your protein powders as a supplement to your diet, but often people use protein powder as a meal shake. As a substitute to real food. Many protein powders have not been designed for this purpose.

Following a diet where you are relying on protein powder for the majority of your calories can cause a lot of digestive distress.

Stomach pain, gastrointestinal symptoms, and nausea can all be affected by consuming more protein than usual.

Alternatives to Protein Shakes

If you are finding that your whey protein is causing you nausea, then you have a number of options. You can find a protein shake that does not include whey, a vegan protein powder for example, or you can look at some other alternatives.

High-Protein Foods

The first option is to focus on getting more real food protein from your diet. For example, instead of a post workout shake you could have a post workout protein bar or whole food option.

Eating a high-protein breakfast as a pre-workout can help if your usual shake makes you feel sick or experience gut issues. Oats, eggs, lean meats, or plant-protein options are all fantastic options, and all can help you to fuel up during an anabolic window.

You can also look to increase protein in your lunches, evening meals, and snacks. This can help you to fuel protein synthesis, and it will encourage you to eat a more varied and potentially healthier diet.

Meal Replacement Shakes

Meal shakes are often seen as a great way to lose weight, but they are better used as a way to increase your protein uptake and improve your overall nutrition. Of course, not all meal shakes are the same.

Many contain artificial ingredients just like protein shakes, meaning that you may still suffer from upset stomachs, bloating, feel sick, suffer from abdominal pain, and other adverse affects.

But if you can find a good quality meal shake that is free from lactose, is high in plant protein, contains a decent number of calories, and uses real food ingredients, then you can get all the benefits of a high protein meal in your shaker bottle.

Why Rootana is the Perfect Alternative to Protein Powder

Rootana contains 400 calories of plant-based ingredients: oats, pea protein, flaxseed, sunflower seed oil, and coconut sugars.

It is high in protein, high in fibre, and it avoids the use of refined carbohydrates. It is also free from artificial ingredients, preferring food options which are better for your digestion.

Rootana also contains a number of nutrients, vitamins and minerals.

Rootana is sweetened differently to the vast majority of meal shakes and protein shakes, it uses a small amount of coconut sugars instead of artificial ingredients to provide a mildly sweet taste.

Thanks to all of this, Rootana is a superior way to get your protein in, particularly if you find that protein powder makes you nauseous and you prefer food and nutrients in your drink.

Why Do Protein Shakes Make Me Nauseous: Final Thoughts

There are many possible causes of nausea. This is one of the reasons why it is so frustrating to suffer from it. If you have managed to pinpoint the cause of nausea to your protein supplement, then there are several different reasons why it has caused your nausea.

It could be that your supplement is of bad quality, or it could be that you are using it in a manner likely to cause nausea. You can either try to fix this and look to remove issues such as bloating through dietary changes, or you can swap your protein powders for meal shakes such as Rootana.

Protein can be a difficult macronutrient to get enough of, but with changes to your eating habits and a drink of Rootana you can hit your protein, fat, carbohydrate, and fibre targets with ease.

Frequently Asked Questions

Can mixing my protein powder with Greek yogurt help with nausea?

If your nausea comes from the lactose in whey protein, then adding Greek yogurt will exacerbate the issue. But, if your nausea is caused by you drinking your shakes too quickly, then mixing with Greek yogurt is a good idea as it can force you to slow down.

Will a post workout protein shake cause nausea?

Possibly, for all the reasons listed above (dehydration, drinking too fast, digestive issues), but it may just be the workout itself that is causing your nausea. High-intensity exercise can make you sick if you overdo it in the gym.

Can protein powders cause an upset stomach?

It is certainly possible for protein powders to cause an upset stomach, but there may be many other factors at play.

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The Nutrition You Need. And Nothing You Don't.

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Complete Nutrition: Perfect Balance of Macros, Vitamins & Minerals

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No Half Measures: 400 Calories Per Serving

Many meal shakes are simply too low in calories and too high in protein to be a complete meal, meaning they're little more than a protein shake. Rootana fuels you effectively and has the perfect macro split for a balanced meal.

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No Sweeteners: No Stevia, No Sucralose, No Aspartame, No Acesulfame K, No Monk Fruit

We don't include any sweeteners as they don't provide any nutritional benefit and may have short or long-term unwanted effects. Rootana is naturally flavored with a small amount of coconut sugar.

Tastes Like Real Food: Because It Is Real Food

With no sweeteners like acesulfame k, aspartame, stevia or sucralose (Splenda), Rootana tastes like real food. That means no artificial after taste and none of that bloated feeling that many sweeteners cause.