Blueberries are a healthy, sweet and tangy fruit often added to yogurt, cereal or simply eaten by the handful. Some people experience adverse reactions, such as diarrhea, when eating blueberries. Diarrhea after eating blueberries can occur from food contamination with bacteria or other harmful substance, or as part of an allergic or sensitivity reaction. See your doctor if you develop severe diarrhea after eating blueberries or if you develop symptoms every time you indulge in a blueberry treat.
Produce is a common source of food poisoning, according to PubMed Health. Blueberries can become infected at any point during processing. Infectious organisms can contaminate the fruit during harvesting or packaging. Contamination may also occur in your own home. The most effective way to prevent food poisoning from blueberries is to wash the berries well before ingesting them. Food poisoning can cause diarrhea, along with vomiting, stomach cramping, abdominal pain and a low-grade fever. Most symptoms from food poisoning are short term and do not typically cause any long-term complications in most people, but if you become dehydrated or very weak as a result of severe diarrhea, seek medical attention.
If you're allergic to blueberries, you're likely to have diarrhea every time you consume blueberries. An over-reactive immune system response to certain proteins causes allergy symptoms. Your immune system creates antibodies to fight the blueberry proteins, which it views as harmful, although these proteins don't cause reactions in most people. In response, your body produces various chemicals to defend itself. The result is inflammation of soft tissue, such as that found in your digestive system. Diarrhea may be accompanied by nasal congestion, asthma, skin rashes and vomiting, according to the American College of Allergy, Asthma and Immunology.
Salicylate sensitivity can also cause stomach upsets such as diarrhea after eating blueberries. Salicylate is a chemical that naturally occurs in a variety of fruits and vegetables, including blueberries. It helps protect the plant during the growth process and is very similar in chemical composition to aspirin. If you're sensitive to aspirin, you're more likely to react to salicylate in blueberries and other produce. This condition differs from a food allergy because it is not triggered by an overreaction of the immune system, but rather occurs because of a general intolerance to the chemical.
Diarrhea that lasts for more than three days or is bloody may be related to a more serious medical condition. Chronic diarrhea from eating certain foods may also be related to irritable bowel syndrome. Talk with a gastroenterologist for proper diagnosis and treatment options.