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Healthy Children > Tips & Tools > KidsDoc Symptom Checker > symptomviewer
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Food Allergy

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Definition

  • Allergic reactions to foods
  • The most common symptom is hives
  • Questions about food allergies
  • Oral Allergy Syndrome is also covered. The main symptom is mouth itching and swelling. The main triggers are raw fruits and veggies.

Symptoms of Food Allergies

  • Hives all over and swelling of the face are the most common symptoms. Hives are raised pink bumps with pale centers (welts). They look like bug bites.
  • Mouth itching and swelling
  • Runny nose and coughing
  • Vomiting and diarrhea
  • Life-threatening allergic reactions also must have trouble breathing and/or swallowing. The medical name for this is anaphylaxis. Most of these reactions have a sudden onset within 10 to 20 minutes. All occur within 2 hours of eating a certain food. People who have had this carry an emergency kit like an Epi-Pen.

Causes of Food Allergies

  • 8 foods cause 90% of food allergies
  • In the first year of life: cow's milk, soy milk and egg
  • Older children: peanuts, tree nuts, fish, shellfish and wheat
  • Shellfish include shrimp, crab, lobster, clams, oysters and scallops
  • Tree nuts include all the nuts (such as almonds and cashews) except peanuts.
  • Of children with a proven food allergy, 40% have severe reactions. The other 60% have mild reactions.
  • Peanuts and tree nuts are the most common triggers for severe reactions.

Cross Reactions with Other Foods

Children with allergies listed below can react to other foods:

  • Cow's milk allergy: 90% also react with goat's milk and 40% with soy milk
  • Egg: 5% react with chicken
  • Peanut: 5% react with other legumes (like peas or beans). About 30% also react to tree nuts.
  • Tree nut: 40% react with other tree nuts
  • Fish: 50% react with other fish. Only 10% also react to shellfish.
  • Shellfish: 70% react with other shellfish
  • Melon: 90% react with banana and avocado

How Long do Food Allergies Last?

  • Cow's milk: 80% outgrown by age 16
  • Soy milk: 80% by age 16
  • Egg: 70% by age 16
  • Peanut: 20% by age 16
  • Tree nut: 10% by age 16

Allergic Disease - Can You Prevent with Diet?

  • Most allergic diseases (food allergies, eczema and asthma) cannot be prevented.
  • Helpful: feeding only breastmilk for 6 months or longer
  • Not helpful: avoiding high-risk foods for pregnant or breastfeeding women
  • Not helpful: soy formulas instead of cow's milk formula
  • Not helpful: a delay in starting baby foods past 6 months
  • Not helpful: a delay in starting high-risk foods like peanut butter or eggs
  • Source: AAP

Oral Allergy Syndrome (OAS)

  • A minor reaction to some raw fruits and veggies
  • Causes itching and swelling only to the lips and tongue
  • Also called Pollen-Food Syndrome

Symptoms of OAS

  • Rapid onset of itching (or tingling) and swelling of the mouth.
  • This can involve the lips, tongue, throat, and roof of the mouth.
  • The uvula (tag of tissue hanging down in back) can become very swollen.
  • These symptoms follow eating a high-risk raw fruit or veggie.
  • OAS can start by age 5.
  • Serious symptoms or very bad reactions rarely happen.

Causes of OAS

  • A contact allergy. It only involves the parts of the mouth that touch the raw food.
  • Trigger foods for OAS are always raw (not cooked.)
  • Fresh Fruits. These include apple, apricot, banana, cherry, melons, orange, peach and pear.
  • Raw Veggies. These include carrot, celery, parsley, potato and tomato. Carrots and celery have the highest risk for also causing serious symptoms.
  • Certain Seeds. These include sunflower seeds and fennel seeds.

OAS and Nose Allergies Can Be Linked

  • Over 50% of people who are allergic to pollen also have OAS. This means 10% of all people.
  • Ragweed pollen allergy can cross-react with all melons. Also, sometimes with bananas and tomatoes.
  • Birch pollen allergy can cross-react with raw potatoes, carrots, celery and apples.
  • Grass pollen allergy can cross-react with tomato and kiwi.
Barton Schmitt MD, FAAP
Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.
Copyright 2000-2025 Schmitt Pediatric Guidelines LLC.
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