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  • Denise Scott

Introducing Allergenic Foods - How to Proceed

Allergenic foods are designated as The Big 9. These include:

  • milk and dairy

  • eggs

  • wheat

  • soy

  • peanuts

  • tree nuts

  • fish

  • shellfish

  • sesame

Pictured are a number of the Big 9 allergenic foods including eggs, milk, wheat, fish, shellfish, nuts, and peanuts.

What are the signs to watch for?

What if my baby reacts?

When is it safe to offer these foods?

Can more than one be given at a time or on the same day?

These questions and more will be answered in this article. Read on!

The recommendations for introducing allergenic foods have changed dramatically over the past decade. When it was recommended that some of these items be delayed until two, more food allergies were seen. Many of these foods can now be offered as early as six months, but there are guidelines to follow. 

Some food allergies may be outgrown during childhood or adolescence (cow’s milk, egg, wheat, and soy allergies), while others can remain lifelong (fish, shellfish, peanut). If an infant reacts, it is best to have them seen by an allergist who can perform additional testing and monitoring. For those with a family history of specific food allergies in a parent or sibling and a history of eczema, discuss when to introduce these items with your child’s doctor. For additional information regarding food allergies, see

Let’s start with reactions to watch for when introducing any new foods. These symptoms can appear within minutes or up to 2 hours.

Mild symptoms include:

  • Acute rash

  • Hives or urticaria (welts or a raised itchy rash)

  • Eczema

  • Sudden nasal congestion or runny nose

  • Itching or tingling in the mouth

  • Abdominal pain

  • Vomiting or diarrhea

  • Blood in the stool

  • Dry cough

  • Swelling of the lips, face, or eyes

Severe symptoms include:

  • Trouble swallowing

  • Difficulty breathing or wheezing

  • Swelling of the tongue or throat

  • Hoarseness with trouble talking

  • Chest pain

  • A sudden drop in blood pressure

  • Fainting

  • Anaphylaxis

If you suspect an allergic reaction in your child, do not give that food again. For mild symptoms, a call to your child’s doctor is in order. A more severe reaction warrants an emergency room visit where medication can be given to counteract the reaction.

Any infant who reacts to a new food should be evaluated by their doctor and an allergist. Subsequent encounters with the same food can potentially cause a worse reaction. If a child has a true food allergy, reading food labels is vital to look for cross-contamination. 

Babies who develop eczema before three months are at risk for cow’s milk allergy. Those with cow’s milk allergy may also react to soy and your pediatrician can guide you about possible testing prior to introducing these foods. 

Some allergenic foods should not be introduced prior to a year. These include cow’s milk and shellfish. Fish and shellfish allergies are likely lifelong and can be so strong that cooking fish in the home can trigger a reaction.

Various shellfish depicted here. Shellfish and cow's milk are two allergenic foods that should not be introduced before a year.

The majority of the Big 9 can be introduced between 6-12 months with the following guidelines:

  1. Only introduce a single allergenic food in a week.

  2. Start with a tiny amount (⅛-¼ teaspoon) and give several days in a row.

  3. If a reaction occurs, do NOT offer the food again and wait until an allergist can evaluate your infant. Wait at least another week before giving a different allergenic food.

  4. If the new item is tolerated, continue to offer this food in gradually increasing amounts 2-3 times weekly.

  5. In a separate week, another new, allergenic food can be offered while continuing the food already tolerated.

  6. Any nut items should be offered as nut butter or powder since nuts are a choking hazard.

  7. Dairy can first be offered as plain, full fat yogurt.

  8. Cow’s milk and shellfish should not be offered before the first birthday.

  9. Do not offer more than one allergenic food in the same week.

  10. It is best to introduce a new food early in the day to have plenty of time to observe before bedtime.

You can continue offering new, non-allergenic foods the same week as allergenic items, but only give one new allergenic food in the same week.

Word of caution - as mentioned in my article on baby cereals, there is a cereal available that combines baby cereals and other baby foods with multiple top allergens (as many as 9, it states on the packaging). This is potentially dangerous and goes against the American Academy of Pediatrics and the American Academy of Allergy, Asthma, and Immunology recommendations.

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