The first year of parenthood is filled with important questions about timing: When will the baby roll over? When will they sleep through the night? And critically, when should you introduce potential food allergens?
The guidance on introducing allergenic foods has changed significantly in recent years. Today, experts recommend early exposure to help prevent the development of food allergies. Below, we explain the optimal timing for starting this process, identify key risk factors, outline how to safely introduce the foods, and detail when to contact a doctor.
The Importance of Early Allergen Introduction
In the past, many pediatricians advised parents to delay the introduction of common food allergens until a baby was one or two years old. However, newer research, particularly large studies involving peanuts and eggs, has demonstrated that delayed introduction offers no protective effect against allergies.
In fact, recent evidence suggests that early, regular exposure to allergenic foods—such as milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish—may actually help prevent the associated allergy from developing, even in babies who have a higher risk.
Despite the change in recommendations, introducing allergens always carries a small risk of an allergic reaction. Therefore, the safest approach is to consult with your child’s pediatrician before beginning the process to ensure you have tailored guidance for your baby.
Babies at Higher Risk for Food Allergies
A baby is considered to have a slightly increased risk for developing a food allergy if a parent or sibling has a known allergy. However, the strongest risk factors include:
- If your baby currently has or has a history of eczema.
- If your baby has had an immediate allergic reaction to any food previously, or reacted to food components passed through breast milk.
It is important to note that up to 50% of children with one food allergy in the United States have allergies to multiple foods.
When to Begin Introduction
With your pediatrician’s approval, you can typically start introducing allergenic foods once your baby has successfully tolerated a few non-allergenic solids (like rice cereal or pureed fruits and vegetables). The baby must also meet key developmental readiness signs, which usually happens between 4 and 6 months of age:
- Can sit up with or without support.
- Has good control of their head and neck.
- Reaches for objects and brings them toward their mouth.
- Can move food to the back of their tongue to swallow (does not immediately push food out).
Safe Steps for Allergen Introduction
Before starting, always consult your pediatrician for recommendations specific to your child, especially if they are considered high-risk.
Step 1: Start Small and Focus on One Food
Introduce only one allergenic food at a time, using a very small amount. This strategy minimizes the risk to your baby and makes it easy to pinpoint which food caused the reaction if one occurs. Examples include:
- Mixing 1/4 teaspoon (tsp) of smooth peanut butter into your baby’s established food (like pureed applesauce or cereal).
- Mixing a small amount of well-cooked, scrambled egg into their cereal.
Step 2: Time It Right and Increase Gradually
It is best to give your baby the allergenic food during their first meal of the day. This allows you to monitor them for up to two hours afterward, as most acute allergic reactions occur rapidly.
- If there is no reaction to the initial dose, gradually increase the amount in following servings.
- If there is still no reaction after 3 to 5 days of continuous, small exposure to the first allergen, you can move on to testing a different food allergen.
Step 3: Maintain Exposure
Crucially, to maintain tolerance and protection against developing the allergy, you must continue to give your baby any non-reactive food allergens 2 to 3 times per week once they are introduced.
Identifying and Responding to Allergic Reactions
If you suspect a reaction to a new food, stop feeding that food immediately. The required next step depends on the severity of the symptoms.
Mild Reaction (Call Your Pediatrician)
Symptoms are typically limited to the skin and may include:
- Hives, welts, or rashes.
Moderate Reaction (Call Your Pediatrician)
These symptoms may appear along with the mild symptoms above:
- Swelling of the lips, eyes, or face.
- Diarrhea or vomiting.
- Sudden changes in behavior (such as extreme fussiness or irritability).
Severe Reaction (Call Emergency Services / 911)
A severe reaction (anaphylaxis) requires immediate emergency medical care. Symptoms include:
- Difficult or wheezy breathing.
- Swelling of the throat or tongue (which may cause drooling).
- Coughing, choking, or a change/difficulty with vocalizing or crying.
- Pale skin or bluish tint.
- Limpness or sudden loss of consciousness.
Understanding your child’s risk and safely introducing allergens is a vital part of proactive parenting. If you have any concerns about your baby’s allergy risk, or need precise guidance on testing methods, do not hesitate to speak with a pediatrician or seek a referral to an allergist.
Frequently Asked Questions: Introducing Allergens
A. While the "Top 8" (milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish) account for about 90% of all food allergies, your baby can theoretically be allergic to any food. However, public health guidance prioritizes the early introduction of these eight major allergens due to their prevalence.
A. After successfully introducing one allergen (meaning you have given it 3–5 times without reaction), you can start the process with the next new allergen. It is vital to continue feeding the previously tolerated allergen 2–3 times a week to maintain tolerance.
A. You should introduce the food when you can closely supervise your baby for the next two hours. Many parents choose to do this early in the day. Be sure to wash the baby's hands and face after the feeding to remove any residue, as skin contact can sometimes trigger localized rashes.