Q: I recently fed my almost-3-year-old son kiwi, and he immediately complained that his “mouth hurt”. His top lip did appear somewhat swollen. We have no history of food allergies in the family, and he has eaten kiwi four or five times before without any reaction. I won’t give it to him again, but what are my next steps?
Dr. Waserman: Kiwi has indeed been associated with acute allergic reactions and anaphylaxis. In fact, kiwi allergy  is becoming much more prevalent in North America as this fruit’s popularity grows, and as more of us are including it in our diets.
It also cross-reacts with many other foods and substances, including birch pollen, avocado, banana, hazelnuts and latex; this means the allergens share similar properties and can react in the same way in the body.
Even though your son had eaten kiwi before without a problem, lip swelling is often a symptom of allergy and you are correct to avoid it. Speak to your doctor about seeing an allergist for a proper assessment of whether this is a true allergy.
Dr. Susan Waserman is an allergist and Professor of Medicine in the Division of Allergy and Clinical Immunology at McMaster University in Hamilton, Ont. She is also a past president of the Canadian Society of Allergy and Clinical Immunology.
See also: Serious Fruit Allergy: Kiwi