Peanut allergy symptoms in babies may include vomiting, hives, facial swelling, and others. They can be mild or severe.

An estimated 1–2% of children have a peanut allergy.

An allergy is an immune system response. When someone has an allergy, their immune system recognizes a harmless substance as a threat and mounts a response. The National Library of Medicine calls this a “false alarm.”

This article will explain the signs and symptoms of a peanut allergy, what to do if an infant has a reaction to peanuts, and how to get a peanut allergy diagnosis.

It will also discuss how to introduce peanuts to children safely and answer some frequently asked questions.

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In most cases, allergic reactions are mild. The signs and symptoms of mild to moderate peanut allergy in babies may include:

  • itchy or runny nose
  • sneezing
  • itchy mouth
  • hives
  • mild itching
  • mild nausea
  • mild gut discomfort

Next steps

Parents or caregivers who notice mild symptoms of an allergic reaction in a baby should contact a pediatrician. They may recommend antihistamine medication, such as Zyrtec.

Sometimes, a peanut allergy can be serious or even life threatening. Severe symptoms include:

  • shortness of breath or wheezing
  • difficulty breathing
  • difficulty swallowing
  • tight or hoarse throat
  • repetitive cough
  • weak pulse
  • dizziness
  • pale or blueish skin
  • a large quantity of hives
  • repetitive vomiting
  • diarrhea
  • significant swelling of the lips or tongue

Next steps

Anyone who notices the signs and symptoms of a severe food reaction in a baby should call 911 immediately.

The American College of Allergy, Asthma, & Immunology (ACAAI) states that most symptoms will occur within 2 hours after exposure to the peanut. They usually begin within minutes.

There are less common types of peanut allergies, which may cause delayed symptoms.

For example, some infants may develop an allergy called food protein-induced enterocolitis syndrome, where the most prominent symptom is vomiting several hours after eating peanuts.

Introducing peanuts into a baby’s diet early on can help prevent a peanut allergy from developing.

The ACAAI provides the following guidelines on preventing a peanut allergy according to the infant’s risk.

High risk

A baby may have a high risk of developing a peanut allergy if they have severe eczema or an egg allergy.

If a baby has a high chance of developing a peanut allergy, a parent or caregiver should take them to get tested for a peanut allergy at around 4–6 months of age. An allergist can perform a skin test or a blood test.

If an allergist is unavailable, a pediatrician can test for certain antibodies to peanuts in the blood.

If the skin test or blood test is negative, parents and caregivers can introduce peanuts at home, slowly and under strict supervision.

If the testing suggests that the infant has a peanut allergy, they can try peanut butter in the doctor’s office to monitor for any possible reactions.

However, if the testing is strongly positive, healthcare professionals will advise parents and caregivers to avoid giving peanuts to infants entirely.

Moderate and low risk

Babies with a moderate risk of developing a peanut allergy do not require testing. They can try peanut products regularly from around 6 months of age, but not before 4 months.

The United Kingdom’s National Health Service (NHS) states that a person can introduce crushed or ground peanuts to an infant with a low risk of developing a peanut allergy from approximately 6 months old.

Delaying the introduction of peanuts to an infant’s diet until after they reach 6–12 months of age can increase the risk of developing a peanut allergy.

It is important not to give a baby whole or pieces of peanut or chunky or crunchy peanut butter, as these can pose choking hazards.

It is possible to thin creamy peanut butter with water or another type of pureed food to avoid the risk of choking.

The Food Allergy Research & Education (FARE) offers the following advice on introducing peanuts to children:

  1. At home or in a doctor’s office, offer the baby a small taste of a peanut-based food on the tip of a spoon.
  2. Wait 10 minutes.
  3. If there is no allergic reaction, the parent or caregiver can offer the remaining food slowly.

Steps for infants with severe eczema or another food allergy

When a baby has severe eczema or an egg allergy, it is best to speak with a doctor before trying to introduce peanuts into the infant’s diet at home.

The Australian Society of Clinical Immunology and Allergy suggests the following steps when introducing peanuts to infants who have severe eczema or another food allergy:

  1. Rub a tiny amount of peanut butter on the inside of the lip, being careful to avoid the skin.
  2. Observe the infant for a few minutes to ensure no allergic reaction develops.
  3. If no reaction occurs, feed the infant a one-quarter teaspoon of smooth peanut butter.
  4. Observe the infant for 30 minutes.
  5. If no reaction occurs, parents and caregivers can gradually include peanuts into the infant’s diet.
  6. If an allergic reaction occurs, seek medical advice immediately.

The ACAAI recommends anyone who experiences an allergic reaction see an allergist.

Before the appointment, it may help the parent or caregiver to note down:

  • what and how much the baby ate
  • how long after eating the peanut butter product the symptoms started
  • what they did to relieve the symptoms
  • how long it took for the symptoms to get better

To make a diagnosis, the allergist may recommend a skin-prick test, where they apply a small amount of peanut extract to the skin with a skin-prick test device. They may also recommend blood tests.

In some cases, they may also suggest an oral food challenge. During this test, the doctors will feed the baby increasing amounts of peanut or peanut-based products over a set time.

The ACAAI makes clear that emergency medication and equipment would be on hand throughout the test in case of a severe reaction.

Here are answers to some common questions regarding peanut allergies in babies.

Is it possible to outgrow a peanut allergy?

A peanut allergy is usually lifelong.

However, around 20% of children will outgrow a peanut allergy.

Are airborne peanut allergies real?

When food manufacturers are making peanut products, they may grind or pulverize them. This can send small pieces of the peanut into the air.

If someone with a peanut allergy inhales these small particles, it can lead to an allergic reaction.

However, a baby will not have an allergic reaction just by being close to a peanut.

Can a baby develop an allergic reaction to peanuts via breastfeeding?

A recent study suggested that eating peanuts during pregnancy or breastfeeding does not contribute to a peanut allergy in the baby.

Symptoms of a peanut allergy in babies can be mild, moderate, or severe.

Parents or caregivers should contact emergency medical services immediately if a severe reaction develops. Some symptoms of a severe reaction include shortness of breath, difficulty breathing, wheezing, a weak pulse, pale or bluish skin, and significant swelling, among others.

Mild or moderate reactions can include an itchy or runny nose, sneezing, an itchy mouth, mild hives and itching, nausea, and gut discomfort. In these cases, a parent or caregiver should contact a doctor.

Symptoms usually develop within minutes after eating a peanut product.

Adding peanuts regularly to the infant’s diet starting from 6 months of age can reduce the risk of a peanut allergy.

If a parent or caregiver has any hesitations about introducing peanuts to their infant’s diet, they should address these concerns with a doctor. Delaying introduction beyond 6–12 months of age can increase the risk of the infant developing a peanut allergy.