Is Your Eczema an Allergy? Finding Hidden Triggers in Your Blood

When to Seek Urgent Help

Eczema itself is not a medical emergency, but it can sometimes overlap with conditions that need urgent attention. Know when to act immediately.

The Science in Plain English

What Is Atopic Dermatitis?

Atopic dermatitis — commonly known as eczema — is a chronic skin condition characterised by dry, itchy, inflamed skin that flares and settles over time. It affects around 1 in 5 children and 1 in 10 adults in the UK, making it one of the most common chronic skin conditions seen in primary care.

The word "atopic" is key. It means the immune system has a tendency to overreact to environmental substances — and people with atopic dermatitis are statistically more likely to also have hay fever, asthma, or food allergies. This cluster is known as the "atopic march."

How Allergy Can Drive Eczema

Not all eczema is allergy-driven — irritants, temperature changes, stress, and skin barrier dysfunction all play a role. However, in a significant proportion of patients — particularly children with moderate-to-severe eczema — allergic sensitisation to environmental or food allergens can be a major contributing factor.

The mechanism works like this: when a sensitised person is exposed to an allergen (through inhalation, skin contact, or ingestion), their IgE antibodies trigger an inflammatory cascade that can worsen the skin barrier and provoke or intensify eczema flares. Common eczema triggers with an allergic basis include:

• Dust mites — the single most common indoor allergen linked to atopic dermatitis. Dust mite proteins can penetrate damaged eczematous skin directly.
• Pet dander — cat and dog allergens are frequently associated with eczema flares, particularly in households with pets.
• Pollen — seasonal worsening of eczema (especially on exposed skin areas) may indicate pollen-driven flares.
• Foods — in young children especially, cow's milk, egg, wheat, soya, and peanut are the most commonly implicated food allergens in eczema.

Most standard eczema treatment focuses on managing the skin: emollients, topical steroids, and avoiding irritants. These are essential — but if an underlying allergic trigger is driving your flares, treating only the skin without addressing the trigger is like mopping the floor while the tap is still running.

Sensitisation vs Clinical Allergy

An allergy blood test detects sensitisation — the presence of IgE antibodies against a specific allergen. This does not automatically mean that allergen is causing your eczema. Some people are sensitised to substances they tolerate without any skin reaction.

However, when sensitisation is found alongside a clear pattern of eczema flares linked to that exposure, it provides a strong clinical clue. Your clinician can use this information — alongside your symptom diary and history — to build a more targeted eczema treatment plan.

Why Blood Testing Is the Practical Choice for Eczema Patients

This is where the eczema-allergy connection creates a specific diagnostic challenge — and where IgE blood testing has a clear advantage.

The Skin Prick Testing Problem

Skin prick testing (SPT) is a well-established allergy investigation — but it requires clear, uninflamed skin at the test site. For many eczema patients, this is precisely what they do not have. If eczema affects the forearms or back (the usual SPT sites), results can be unreliable or the test may not be possible at all.

Additionally, skin prick testing requires stopping antihistamines for several days beforehand. Many people with chronic eczema and associated itch rely on daily antihistamines — and stopping them can mean days of intensified itching and sleep disruption simply to enable a test.

IgE Blood Testing: A Skin Prick Alternative

An IgE blood test avoids both of these problems entirely:

For eczema patients specifically, IgE blood testing is not just an alternative to skin prick testing — it is often the preferred investigation because the very condition being investigated (inflamed skin) makes SPT unreliable. For a broader comparison of the two methods, see our guide on blood test vs skin prick: which allergy test is more accurate.

Common Eczema Triggers That Blood Testing Can Identify

Dust Mites

Dust mite allergy is the most frequently identified allergen in people with atopic dermatitis. The proteins in dust mite droppings can penetrate the compromised skin barrier directly, as well as being inhaled. Many patients with eczema notice their skin is worse at night or in the morning — when prolonged contact with bedding (where dust mites concentrate) is at its peak.

If dust mite sensitisation is confirmed by blood testing, targeted environmental measures — allergen-proof bedding covers, regular high-temperature washing, HEPA-filter vacuuming — can be focused where they will have the greatest impact. For practical dust mite reduction strategies, see our article on how to get rid of dust mites in your home.

Pet Dander

Cat and dog allergens are common triggers for eczema flares — particularly in children. Cat allergen (Fel d 1) is especially problematic because it is extremely lightweight and persistent: it clings to furniture, clothing, and soft furnishings, and can be found even in homes without cats.

Blood testing can distinguish between cat and dog sensitisation individually, allowing you to make informed decisions about pet allergy management rather than applying blanket avoidance advice.

Foods

In children under five with moderate-to-severe eczema that is not responding well to standard treatment, food allergy may be a contributing factor. The most commonly implicated foods include cow's milk, hen's egg, wheat, soya, and peanut.

However, food allergy as an eczema trigger is less common in older children and adults than many people assume. Removing foods from the diet without proper investigation can cause more harm than good — leading to nutritional deficiencies, food anxiety, and in some cases, an increased risk of developing allergy to the removed food. Any suspected food trigger should be investigated through appropriate testing and clinical assessment, not self-diagnosed elimination.

Pollen

Some people with atopic dermatitis notice seasonal worsening of their skin — particularly on exposed areas such as the face, neck, and arms during spring and summer. This can indicate pollen-driven eczema, where airborne pollen particles settle on the skin and trigger inflammation.

If blood testing confirms pollen sensitisation alongside a seasonal eczema pattern, strategies such as showering after being outdoors, keeping windows closed during high pollen counts, and applying emollient as a barrier before going outside can be targeted specifically to the relevant pollen season.

What Results Can (and Can't) Tell You

What a Positive Result Means for Eczema

A positive IgE result shows sensitisation — it does not automatically confirm that the allergen is driving your eczema. However, when sensitisation correlates with your flare pattern (e.g., dust mite sensitisation in someone whose eczema is consistently worse at night), it provides actionable clinical information.

The value for eczema patients is this: rather than trying every possible intervention at once, you can focus on the triggers your blood results — combined with your symptom diary — point to. This approach is more efficient, less disruptive to daily life, and more likely to produce a meaningful improvement.

What a Negative Result Means

If IgE testing returns negative for all allergens tested, it makes allergic sensitisation less likely as a driver of your eczema. This is still useful information: it means your eczema treatment plan can focus on skin barrier repair, irritant avoidance, and topical therapies without the added complexity of allergen management.

Contact Allergy: A Different Pathway

It is worth noting that IgE blood tests detect type I (immediate) hypersensitivity. A different type of allergy — contact allergy (type IV, delayed hypersensitivity) — is not detected by IgE testing. Contact allergy is caused by substances like nickel, fragrances, preservatives, or rubber, and is investigated using patch testing arranged through dermatology services.

If your eczema consistently affects areas in contact with jewellery, watch straps, cosmetics, or specific clothing materials, contact allergy should be considered alongside IgE-mediated triggers. Your GP or dermatologist can arrange patch testing if appropriate.

Total IgE in Eczema

People with atopic dermatitis often have elevated total IgE levels — sometimes significantly so. While this reflects the underlying atopic tendency, total IgE alone does not identify specific triggers. Specific IgE testing (measuring antibodies to individual allergens) is what provides the actionable information.

Practical Next Steps (UK Pathway)

1. Keep an Eczema Flare Diary

Before booking any test, start tracking your flares. Record when they happen, where on the body they appear, what you ate, where you were, and any potential exposures (new laundry detergent, visiting a home with pets, high pollen count days). Look for patterns — consistency is the clue. Note whether eczema is worse at certain times of day, certain seasons, or in certain environments.

2. Optimise Your Baseline Eczema Treatment

Allergy investigation works best alongside good baseline eczema care — regular emollients, appropriate use of topical treatments, and avoidance of known irritants (harsh soaps, fragranced products). If your baseline care is not optimised, it becomes harder to identify whether allergens are genuinely contributing or whether poor skin care is the primary issue.

3. Get Tested to Identify Your Specific Triggers

An IgE blood test can screen for the most common eczema-relevant allergens — dust mites, cat, dog, pollen, and key foods — from a single venous blood sample. You do not need to stop antihistamines, and the test is completely unaffected by the state of your skin. Explore the allergy blood test panels available to find the right option.

4. Share Results with Your Clinician

With clear data, your clinician can build a more targeted eczema treatment plan: specific allergen reduction measures for the triggers you are sensitised to, guidance on whether dietary changes are warranted (and if so, with dietitian support), and a clearer picture of whether specialist referral may be beneficial.

5. Avoid Unnecessary Elimination Diets

This point is especially important for children with eczema. It can be tempting to remove multiple foods from the diet in the hope of improving the skin. However, unnecessary elimination — without confirmed allergy — can lead to nutritional deficiencies, anxiety around eating, and may paradoxically increase the risk of developing food allergy. Any dietary changes should be guided by a healthcare professional.

Frequently Asked Questions

Summary

Standard eczema treatment — emollients, topical steroids, irritant avoidance — is essential. But if your eczema is driven or worsened by hidden allergic triggers, treating only the skin without addressing the source means you are managing symptoms, not solving the problem.

• Dust mites, pet dander, pollen, and foods are the most common allergic eczema triggers — an IgE blood test can identify which ones you are sensitised to.
• Blood testing is the ideal investigation for eczema patients: it works regardless of skin condition, requires no antihistamine withdrawal, and carries no risk of worsening your skin.
• Results provide objective data to target your treatment — focusing allergen reduction on the triggers that actually matter to you.
• Sensitisation does not always equal clinical allergy — results should be interpreted alongside your flare pattern and clinical history.
• Do not eliminate foods without clinical guidance — especially in children.

If you want to find out whether hidden allergens are driving your eczema, our nurse-led venous blood testing can screen for the most common triggers from a single blood sample — no need to stop antihistamines, and suitable for all skin types and ages. Browse our allergy blood test panels to see what\u2019s available, or get in touch if you have questions about the booking process.

References Used

• NHS — Atopic Eczema
• NICE — CG57: Atopic eczema in under 12s — diagnosis and management
• NICE — CG116: Food allergy in under 19s — assessment and diagnosis
• Allergy UK — Skin Allergy
• BSACI — Guidelines for the Management of Allergy
• National Eczema Society — Understanding Eczema
• Flohr C, Mann J. "New insights into the epidemiology of childhood atopic dermatitis." Allergy, 2014; 69(1):3–16.
• Eigenmann PA et al. "Testing children for allergies: why, how, who and when." Pediatric Allergy and Immunology, 2013; 24(2):195–209.