5 Reasons Blueberries Could Cause Diarrhea
Blueberries are tasty and nutritious, but they can cause diarrhea in some cases.
Updated on August 6, 2025
Blueberries are a nutritious, sweet fruit often added to yogurt, cereal, or eaten plain by the handful. But some people may have digestive issues, including diarrhea, after eating them. Here are some potential reasons blueberries can cause diarrhea — and what to do about it.
1. Blueberries Are High in Fiber
Fiber is an essential nutrient that helps support good digestion, reduces your risk of constipation, and can also help you maintain a healthy weight and decrease your risk of conditions like diabetes and heart disease. Blueberries are rich in fiber — a cup of the fruit contains nearly 3.5 grams of it.
But eating too much fiber at once or adding too much fiber to your diet too quickly if you’re not accustomed to adequate doses of the nutrient — which can happen if you overload on blueberries — can lead to digestive upset.
Fix It
If you’re not used to high doses of fiber, slowly increase your intake of the nutrient over the course of a few weeks. This will allow your body to adjust without those uncomfortable side effects. Staying hydrated may also help your body better process fiber and keep digestive symptoms at bay.
According to the current Dietary Guidelines for Americans, adults should try to eat between 28 and 34 grams of fiber a day.
2. Contaminated Blueberries Can Cause Food Poisoning
Produce is a common source of food poisoning. Raw fruits like blueberries can become contaminated with germs such as salmonella at any point during their growth and processing. Contamination can also occur in your own home, especially if the produce isn’t properly washed or stored.
And it’s these disease-causing organisms that may be the reason why eating blueberries gives you diarrhea. Indeed, food poisoning can cause loose stools, along with vomiting, stomach cramps, and a low-grade fever.
Fix It
To avoid food poisoning from berries — and the resulting diarrhea — wash them thoroughly and pat them dry before eating, and store them in the refrigerator.
Most symptoms of food poisoning are mild and don’t typically cause any long-term complications, but if you have a high fever or become dehydrated or very weak as a result of severe diarrhea, see your doctor or head to urgent care ASAP.
3. You Could Be Allergic to Blueberries
Food allergies occur when your immune system overreacts to certain proteins in your meal and produces allergic symptoms. It’s basically your immune system mistaking a certain food for something harmful.
And a food allergy may be the reason why blueberries cause diarrhea, as loose stools can be a symptom of an allergic reaction. Other common symptoms include:
- Vomiting
- Skin rash or hives
- Itchy mouth, throat, or skin
- Swelling
- Trouble breathing
Fix It
Food allergy symptoms can vary from person to person, so the only way to know for sure if you’re allergic is to have a doctor do a skin prick or blood test. If your doctor diagnoses you with a blueberry allergy, you’ll need to avoid blueberries going forward.
Some people can have an extreme allergic reaction called anaphylaxis, where your throat closes up and makes it difficult to breathe. Seek medical care immediately if this happens to you.
4. You May Have a Fructose Intolerance
Some people can’t tolerate fructose, a naturally occurring sugar in fruits, some veggies, juices, table sugar, high-fructose corn syrup, and honey. This means the sugar can’t be broken down or digested correctly, which can cause symptoms such as:
- Diarrhea
- Upset stomach
- Gas
Blueberries are relatively low in fructose, but they could trigger symptoms if eaten in large quantities.
Fix It
If you suspect you have a fructose intolerance, see your doctor for a potential diagnosis. If you’re diagnosed with an intolerance, you’ll want to limit how many fructose-containing foods you eat. It may take some trial and error to figure out how much you can tolerate.
5. You Could Have a Salicylate Sensitivity
Salicylate is a chemical found naturally in various fruits and vegetables, including blueberries. It helps protect the plant during the growth process and is very similar in chemical makeup to aspirin.
So, if you’re sensitive to aspirin, your’e more likely to react to salicylate in blueberries and other produce. And having this type of intolerance could be the reason why blueberries cause diarrhea, says Ashley Kravitz, RD, owner of Nutrition Specialists of New Jersey.
Along with diarrhea, other symptoms of a salicylate intolerance or sensitivity include:
- Headache
- Nasal congestion
- Skin rash, hives, or itching
- Itching, watering, or inflammation of the eyes
- Stomach pain
- Nausea
Fix It
Salicylate intolerance to medications is well established, but there’s a lack of research on sensitivity to salicylate in foods. There are no tests to diagnose this intolerance, so your doctor may use the process of elimination by ruling out a food allergy and having you keep a food and symptom diary.
The Takeaway
- If you have diarrhea or digestive upset after eating blueberries, it could be due to their high fiber content, especially if you’re not used to eating a lot of fiber.
- Be aware of the risk of food poisoning with blueberries, as with any raw produce. To reduce this risk, thoroughly wash and dry them before eating them, and refrigerate them properly.
- An allergic reaction to blueberries could manifest as diarrhea or other reactions such as hives and swelling. In severe cases, anaphylaxis can occur, which requires immediate medical attention.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
- Dietary Fiber: Essential for a Healthy Diet. Mayo Clinic. December 11, 2024.
- Nutrition Facts: Blueberries, raw, 1 cup. University of Rochester Medical Center.
- Dietary Guidelines for Americans 2020-2025 . U.S. Department of Agriculture. December 2020.
- Symptoms of Food Poisoning. Centers for Disease Control and Prevention. January 31, 2025.
- Food Poisoning: Symptoms and Causes. Mayo Clinic. February 23, 2024.
- What Is a Food Allergy? Food Allergy Research & Education.
- Food Allergies. Cleveland Clinic. November 11, 2024.
- Food Allergy Testing and Diagnosis. American College of Allergy, Asthma, & Immunology.
- Fructose Intolerance: Which Foods to Avoid? Mayo Clinic. January 9, 2024.
- Low Fructose Diet. University of Virginia Health System. December 2023.
- What Is Fructose Intolerance? Cleveland Clinic. March 1, 2021.
- Understanding Salicylate Sensitivity. Academy of Nutrition and Dietetics.
- Yeasmin F et al. Natural Salicylates and Their Roles in Human Health. International Journal of Molecular Sciences. 2020.
- Salicylate Sensitivity. National Health Service. September 2024.
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