Food allergies occur when the immune system identifies the proteins in a particular food as harmful to the body, subsequently reacting to try to "fight off" the "harmful" proteins (which are in fact harmless). You may have a blueberry allergy if you experience some of the following symptoms after eating or touching blueberries or products that contain blueberries:

  • Itching or swelling of the mouth, tongue or lips
  • Skin reactions, such as eczema, hives, swelling and redness of the extremities or face
  • Gastrointestinal symptoms, such as abdominal pain, nausea, vomiting or diarrhea
  • Respiratory symptoms, such as runny or stuffy nose, coughing, sneezing, wheezing or difficulty breathing
  • Cardiovascular symptoms, such as a drop in blood pressure, lightheadedness or fainting

If you experience symptoms of anaphylaxis, which include nausea, vomiting, weak or rapid pulse, difficulty breathing, confusion and loss of consciousness, seek immediate medical attention, as this can be fatal. Any of the above symptoms may also indicate sensitivity to salicylates, a chemical that acts as a natural preservative in plants. In addition to blueberries, salicylates can be found in many fruits and vegetables, medications and beauty products.

If you have any of the above symptoms after consuming or coming into contact with blueberries, you should see an allergist and be tested to find out whether you have a blueberry allergy or salicylate sensitivity. If you are diagnosed with a blueberry allergy, you'll have to avoid contact with blueberries. If you have salicylate sensitivity you'll need to read labels carefully and look out for aspirin, mint flavorings and other ingredients containing salycilate compounds. If you have a severe allergy or sensitivity, your doctor will prescribe epinephrine to keep with you so you can treat yourself in case of a reaction.