Signs and Symptoms of Allergies in Babies

By Jeanette Bradley 

 Medically reviewed by Jonathan B. Jassey, DO

Food allergies can be hard to spot in babies. The only way to know for sure if your child has a food allergy is to get a formal diagnosis from a healthcare provider.

That said, there are some signs and symptoms of food allergies that you may recognize.

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Some of these can be mild and, on their own, seemingly non-specific. For example, babies can experience nasal stuffiness, skin itching, or coughing as the result of a food allergy.

But other symptoms, like difficulty breathing, can be severe and require emergency care.

In this article, you’ll learn the symptoms to watch for, how to recognize them in your baby, and what’s considered mild or severe. You’ll also learn how long it takes for symptoms to occur and how to prevent allergic reactions in your child.

Can Any Baby Have a Food Allergy?

Yes. However, babies with a close family member with a food allergy are at higher risk for developing one themselves. It’s especially important to watch for signs in these children.

About 3% of infants and almost 9% of 1-year-olds are allergic to at least one food.1

A child can have a reaction from eating a problematic food or from consuming breast milk that contains proteins from the food, which come from a mother’s diet.

Thankfully, most food allergy reactions are mild. However, some can be severe and require immediate medical attention.

Mild Signs and Symptoms of Food Allergy

Food allergies can cause a lot of symptoms. If a child is too young to tell you what’s going on, you may not know about some of them at all.

Other symptoms may be noticeable but have plenty of other potential causes, making them easy to chalk them up to something else entirely.

The key is to take note of what symptoms tend to happen together and whether they come on soon after eating.

Colic

Colic isn’t a specific illness or diagnosis. It’s a descriptive term that means your baby cries inconsolably for at least three hours a day, three days a week, for at least three weeks.

It’s usually a predictable pattern. You can recognize a colic spell by its symptoms:2

• High-pitched crying

• Difficulty being soothed

• Red face, possibly with pale skin around the mouth

• Pulled-up legs, stiffened arms, clenched fits, or arched back

While a food allergy may cause colic, so can several other things. These include being overstimulated, an inability to self-soothe, or a digestive problem.2

There’s no way to distinguish allergy-related colic from any other type of colic. Instead, pay attention to any other symptoms that may occur along with it.

It Might Be Reflux

Healthcare providers now believe that some babies with colic have acid reflux. A percentage of those babies may have a cow’s milk allergy that is causing the condition.3 Your pediatrician can prescribe reflux medication or may suggest switching to a different formula.

Itching

A food allergy can cause itching all over. But a baby won’t be able to show it in the way that you do.

Before they’re old enough to be able to scratch an itch, an itchy baby may squirm in an attempt to rub the itchy spot against something. They may also be fussy.4

Again, a suspected itch isn’t enough to suggest a food allergy. But it’s an important part of the whole picture.

Eczema

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Eczema is a scaly, itchy rash that may become red and raw. It can occur with a food allergy or for other reasons.

This condition can look different depending on your child’s age:5

• 0-6 months: Eczema is usually on the cheeks, chin, forehead, and scalp. Sometimes it spreads to other areas as well. It may look red and weepy.

• 6-12 months: Eczema is most often on the elbows and knees, where the skin is rubbed from crawling. An infected rash may form a yellow crust.

• 2-5 years: Eczema is most likely to be in the creases of the knees and elbows or on the wrists, hands, and ankles. It may look dry, scaly, and thick.

Eczema is rare in the diaper area because of the extra moisture there.5

For babies who are high risk or already have eczema, research shows that two things can reduce the number and severity of eczema flare-ups in the first four months of life:6

• Exclusive breastfeeding

• Supplementing with hypoallergenic hydrolyzed formula

To soothe your baby’s skin, your pediatrician may recommend:

• Oatmeal baths

• Nonsteroidal skin products, such as petroleum jelly

• Cold compresses

• Wet wraps

For severe itching, they may recommend antihistamines or steroid creams.

Hives

Kwangmoozaa / Getty Images

Hives are pink or red bumps with pale centers. They can measure anywhere from half an inch to several inches across, be quite itchy, and may have an irregular shape.

If hives are just in one area, they are likely due to something your child came into physical contact with, like pet saliva or pollen.

However, if they are all over the body, they can point to an allergic reaction or an infection. These hives may even disappear from one area only to turn up in another. Still, only about 3% of cases are due to food allergies.7

Mild hives don’t need to be treated. They should go away on their own within about six hours.7

You can give your child an allergy medicine that’s appropriate for their age to ease symptoms. If they’re over a year old, Benadryl is often the first choice.7 Your pediatrician can make a recommendation if you’re not sure what to use.

Swelling of the Face, Lips, and Eyes

Your baby may take on a “puffy” look in their face, especially in the lips and around the eyes, if they are having an allergic reaction to a food. This is called angioedema.

Treating the allergy with antihistamines should help the angioedema go away. Without treatment, the swelling will likely go away within a few days.8

This symptom is considered mild unless your baby also has swelling in the tongue and throat.8

Oral Allergy Syndrome

Some babies get hives, itching, or swelling around their mouths after eating raw fruits and vegetables. This is from oral allergy syndrome (also called pollen food allergy syndrome), which is a minor reaction. It typically occurs because someone is allergic not to the food itself, but to pollen from trees or grasses. Some foods contain proteins similar enough to the proteins in the pollen to trigger these symptoms.9

Digestive Issues

Food allergies can lead to several digestive symptoms:10

• Abdominal pain: It’s hard to gauge this in a baby. Some signs may be crying inconsolably and pulling their knees to their chest.

• Vomiting: Be sure not to lay your baby down if they’ve been vomiting as they may breathe vomit into their lungs (aspirate).

• Loose stools or diarrhea: This may contain mucus or blood.

If your baby has chronic vomiting or blood or mucus in their diaper, your healthcare provider may want to do some diagnostic testing. They may suggest switching to a special formula as well.10

With vomiting and/or diarrhea, do your best to keep your baby hydrated. If they can’t keep anything down or start showing signs of dehydration, get medical help right away.

Dehydration Symptoms

• No tears when they cry

• Dry lips and tongue

• Low number of wet diapers (six a day is normal for infants)

• Sunken eyes

• Sunken soft spot

• Dry, wrinkly skin

• Deep, rapid breathing

• Cool, blotchy hands and feet11

Classic Allergy Symptoms

A food allergy can give your baby classic allergy symptoms:

• Stuffy, runny nose that can become chronic (allergic rhinitis)

• Sneezing

• Coughing

• Itchy, watery eyes

These symptoms are generally treated with allergy medications.

Recap

A food allergy can give your baby a range of possible allergy symptoms, such as colic, itching, and hives. A single symptom isn’t enough to suggest a food allergy. More than one happening together, and soon after eating the problem food, is a stronger hint that a food allergy is to blame.

Severe Food Allergy Reactions in Babies

Anaphylaxis or anaphylactic shock is a severe, potentially life-threatening allergic reaction.

Anaphylaxis is rare in babies. When it does happen, it may start with sudden hives and difficulty breathing or swallowing.7

Symptoms are most likely to come on right after your baby has been introduced to a new food or formula. Along with typical allergy symptoms above, watch for:12

• Wheezing, difficulty breathing: Listen for a whining or rattling sound. They may gasp for breath or purse their lips to breathe.

• Swelling of mouth, face, or throat: This becomes a concerning symptom when it impairs breathing or swallowing.

• Pale, flushed skin: This symptom may be hard to spot if your baby has hives. It may indicate dropping blood pressure.

• Loss of consciousness: This is a sign of dangerously low blood pressure.

When to Get Emergency Medical Attention

Call 911 immediately if your baby:7

• Develops hives after eating nuts, eggs, fish, or shellfish, taking medicine, or exposure to a known allergen

• Has widespread hives and is under 1 year old

• Suddenly has a cough or sounds hoarse

• Has trouble swallowing

• Has unusual drooling

• Has slurred speech

• Acts or looks sick

• Has other symptoms you’re concerned about

When Do Symptoms Appear?

Symptoms of a food allergy generally appear quickly—within a few minutes after your baby eats the food.

Hives and anaphylaxis—either together or separately—develop between 30 minutes and two hours after eating the problem food.

Your baby may tolerate a food fine at first but develop an allergy later. Allergies can develop at any point in life.13

Foods Most Likely to Cause a Reaction

Any food can trigger an allergic reaction. However, 90% of them are caused by:12

• Milk

• Eggs

• Wheat

• Soy

• Peanuts

• Tree nuts

• Fish

• Shellfish

The majority of kids who are allergic to milk, eggs, wheat, or soy outgrow their food allergies during childhood. Other allergies may last longer or be permanent.14

Recap

Foods most likely to be a problem are milk, eggs, wheat, soy, peanuts, tree nuts, fish, and shellfish. Food allergy symptoms generally appear within minutes of eating the problematic food. Anaphylaxis can occur within a two-hour window. Severe allergies are a medical emergency that warrant calling 911.

What to Do If You Suspect a Food Allergy

Always go to the emergency room or call 911 right away if you suspect a severe allergic reaction in your child.

If you suspect your baby has a food allergy and they seem to only be having mild symptoms:

• Keep a food diary: Write down what your baby eats and drinks along with times and any symptoms that occur within the next two hours. Note symptoms that don’t appear to be food-related, too.

• Check on treatments: Call your pediatrician’s office to ask what allergy medications are safe for your child.

• See your pediatrician: Make an appointment with your child’s regular doctor. They may refer your child to an allergist for further testing.

Preventing Allergic Reactions

If you don’t have allergies, it’s not necessary to avoid possible food allergens during pregnancy. There’s no evidence doing so prevents allergies in the baby.15

The best way to minimize your baby’s risk of allergic reactions is to breastfeed. It’s the least likely thing to trigger a reaction. However, if your baby appears to have a reaction to your breast milk, it may be because they’re allergic to proteins from food you’ve eaten that are passed on through your milk.

Breastfeeding for between 4 and 6 months may also reduce your baby’s risk of eczema, wheezing, and an allergy to cow’s milk.15

Once your baby is between 4 and 6 months old, introduce solid foods with single ingredients, like apple or squash baby food, or rice cereal.

Space out new foods by a few days. Then if your baby does have a reaction, it’s easy to figure out what food is the problem.15

Some people wait to give their baby higher-risk foods like eggs and peanuts, but experts say delaying exposure to those foods may actually increase their risk of food allergies.15

Once you know your baby is allergic to something, the best way to prevent a reaction is to diligently avoid the problem food(s) and anything that could contain them or have come in contact with them.

Summary

About 3% of infants have food allergies and about 9% of 1-year-olds. Symptoms appear quickly after eating foods such as milk, eggs, nuts, and fish. Mild symptoms can include colic, eczema, hives, and runny nose.

Severe reactions (anaphylaxis) happen within two hours. Anaphylaxis involves wheezing or difficulty breathing, mouth and throat swelling, and possibly loss of consciousness. Anaphylaxis is always an emergency that requires immediate medical attention.

You can prevent allergies by breastfeeding. Introducing single-ingredient foods one at a time can help you associate reactions with their causes.

Sources

Gupta RS, Warren CM, Smith BM, et al. The public health impact of parent-reported childhood food allergies in the United States. Pediatrics. 2018;142(6):e20181235. doi:10.1542/peds.2018-1235

KidsHealth. Colic.

de Morais MB. Signs and symptoms associated with digestive tract development. J Pediatr (Rio J). 2016;92(3 Suppl 1):S46-56. doi:10.1016/j.jped.2016.02.008

Children’s National Hospital. How to tell if your child has eczema.

National Eczema Association. Understanding eczema in children.

Greer FR, Sicherer SH, Burks AW, et al. The effects of early nutritional interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeeding, hydrolyzed formulas, and timing of introduction of allergenic complementary foods. Pediatrics. 2019;143(4):e20190281. doi:10.1542/peds.2019-0281

Seattle Children's Hospital. Hives.

MedlinePlus. Angioedema.

American College of Allergy, Asthma & Immunology. Pollen food allergy syndrome.

Boston Children’s Hospital. Allergic colitis.

Cleveland Clinic. Dehydration and your child.

KidsHealth. Food allergies.

University of Pennsylvania Medical Center. Is it possible to suddenly develop allergies?

Caubet JC, Cianferoni A, Groetch M, Nowak‐Wegrzyn A. Food protein‐induced enterocolitis syndrome. Clin Exp Allergy. 2019;49(9):1178-1190. doi:10.1111/cea.13415

American Academy of Allergy, Asthma & Immunology. Prevention of allergies and asthma in children.

By Jeanette Bradley
Jeanette Bradley is a noted food allergy advocate and author of the cookbook, "Food Allergy Kitchen Wizardry: 125 Recipes for People with Allergies"