What does food allergy look like?

There are two main categories of food allergy.

Immediate food allergy (medically known as IgE-mediated)

This is the type of reaction most people think of when they hear the term "food allergy." It happens because the immune system mistakes a specific food for a harmful invader and reacts very quickly to fight it off.

Symptoms usually appear within minutes (and almost always within 2 hours) of eating the food. They happen every time that food is eaten.

Typical signs to look out for:

• Skin: An itchy, raised rash that looks like a nettle sting (hives); swelling of the face, lips, or eyelids.
• Tummy: Sudden vomiting, tummy pain, or diarrhea.
• Breathing or alertness (anaphylaxis): In rare, severe cases, the reaction can affect a child’s breathing (wheezing or coughing) or make them go floppy or unconscious. This is a medical emergency.

Some immediate food allergies resolve over time, but many persist and can be lifelong.

Delayed food allergy (medically known as Non-IgE mediated)

This type of allergy is often trickier to spot because the reaction doesn't happen straight away. It involves a different part of the immune system than the immediate type.

Symptoms typically develop hours or even days after eating the food. Because of this delay, it can sometimes be hard to pinpoint exactly which food is causing the problem.

Typical signs to look out for:

• Skin: This usually presents as a flare-up of eczema, with skin becoming red, dry, and itchy, rather than hives.
• Tummy: Ongoing tummy pain, discomfort, diarrhea, or vomiting.

The good news is that delayed symptoms are not associated with life-threatening breathing reactions (anaphylaxis). Children tend to grow out of this type of allergy, and the food can often be successfully reintroduced to their diet later on.

What are the most common foods causing food allergies in young children?

• Egg
• Milk
• Peanut
• Wheat
• Cod
• Sesame
• Tree nuts

How early eczema increases the risk of immediate food allergy and dry skin

In early life, a baby’s immune system is learning how to recognise what is safe and what is harmful. Normally, foods are introduced through the gut which encourages recognition of the food and a tolerant response.

When eczema is present, especially if it starts early and is severe, the damaged skin barrier can allow food proteins from the environment to enter through the inflamed skin. When the immune system encounters food in this way, through the skin rather than the gut, it may interpret it as a threat.

This process can lead to the development of IgE-mediated food allergy. This mechanism helps explain the so-called allergic march, where eczema in infancy is followed sequentially by food allergy, hayfever and sometimes asthma as a child grows up.

These principles are the core to understanding the approach to preventing food allergies. 

Babies with early-onset, troublesome eczema are at the highest risk of food allergy, particularly if eczema begins within the first few months of life. If your child is showing symptoms it’s important that you get in touch with a specialist allergist to assess the situation and develop a treatment plan that could help prevent the development of food allergies.

How treating eczema early may help prevent immediate food allergies

This understanding has shifted how we think about both eczema and food allergy prevention.

Research led by Professor Gideon Lack, Dr Susan Chan and colleagues, including the ongoing SEAL (Stopping Eczema and Allergy) study, aims to explore whether proactive, early treatment of eczema can reduce the later development of food allergies.

The principle is straightforward: if food allergy develops because allergens enter through damaged skin, then protecting and repairing the skin barrier early may reduce that risk.

This reinforces a key message for parents: Treating eczema well is not just about managing their skin, it may actually prevent future allergies.

Why unnecessary food avoidance can increase allergy risk

It can feel intuitive to remove foods when a baby has eczema. However, we now know that avoiding foods without evidence of allergy can increase the risk that a child will later become allergic to that food.

In addition, avoiding foods unnecessarily risks unnecessary dietary restriction and can be detrimental from a nutritional perspective.

For babies with eczema, the priority is:

• Early recognition and effective treatment of eczema
• In the absence of any food allergies, the safe and timely introduction of allergenic foods.

Evidence from studies such as the LEAP Study, which was conducted by Professor Lack and his team, suggest that the first few months of life are a critical period for some babies in the development of the immune system, as food allergies often develop during this time.

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Can food allergy cause eczema?

Yes, although this is less common.

For example in some children, cow’s milk allergy can contribute to eczema, and may be accompanied by gut symptoms such as discomfort, vomiting or diarrhoea. In these cases, dietary changes may be beneficial following a proper assessment.

Importantly, routine removal of a panel of foods in children with eczema, but without clear allergic reactions, is not recommended and may increase the risk of food allergy developing.

Foods that irritate eczema but are not allergies

Some foods can irritate eczema without causing true allergy. 

Certain foods such as tomato or citrus fruits may cause redness, often around the mouth. These reactions are local, inconsistent, and do not involve hives, swelling or other symptoms elsewhere on the body.

Irritation is very different from allergy and requires practical steps to avoid skin contact, but it does not require food avoidance.

When and how to introduce allergenic foods safely

1. Treat eczema effectively

Use emollients regularly and prescribed anti-inflammatory creams as needed. Used correctly, these treatments are safe and effective. This also heals their skin so that your baby is less itchy and more comfortable, reduces complications such as skin infections and improves disturbed sleep patterns.

2. Introduce allergenic foods early

As long as a food allergy has not already developed, introducing foods such as cow’s milk, egg, and peanut in an age-appropriate form, is recommended from a few months of age. This can help reduce the risk of food allergy, particularly in babies with eczema.

3. Do not remove foods ‘just in case’

Only avoid a food if there is a clear reaction and aim to seek professional advice.

4. Seek specialist input when needed

Referral to a dermatologist may be needed to manage your baby’s eczema. A specialist allergy opinion may be required for food allergy diagnosis and management. The support of a suitably qualified dietitian may also be valuable to optimise nutrition in the context of dietary restrictions. 

When to seek specialist allergy advice

A specialist allergist will take an in-depth history and can perform allergy tests to help support your baby’s allergy journey. Seek specialist input if:

• You suspect your baby is at risk of developing food allergies, particularly if their eczema is severe, early-onset, or difficult to control despite appropriate treatment
• You suspect a food allergy, for example you notice consistent, typical or severe food allergic symptoms after your baby eats a specific food
• You are considering removing major foods such as cow’s milk, egg or wheat
• You need help to identify unrecognised food allergies
• You need guidance on introducing potentially allergenic foods safely
• There is a family history of food allergies in a parent or sibling

Frequently asked questions

Does baby eczema mean food allergy?

Many babies with eczema do not have food allergy. However, early and severe eczema increases the risk of developing food allergy later.

Should I remove foods from my baby’s diet, if my baby has eczema?

Removing foods without clear allergic reactions can increase the risk of allergy, and should be guided by specialist advice.

Can treating eczema help prevent food allergy?

Effective early eczema treatment helps protect the skin barrier and may reduce the risk of food allergy developing.

When should allergenic foods be introduced if my baby has eczema?

From a few months of age, with specialist guidance if eczema is moderate to severe. These foods should be eaten regularly and frequently and continued breastfeeding is encouraged.