eczema blood test explained

Overview

An eczema blood test is a blood sample taken to help understand your eczema better. It is not a test to diagnose eczema itself—that is usually done by looking at your skin and asking about your symptoms. Instead, the blood test checks for certain markers, like immunoglobulin E (IgE) levels, which are linked to allergies and inflammation. This can help your doctor identify possible triggers, such as foods or pollen, and rule out other skin conditions.

Yes, eczema (also called atopic dermatitis) is very common. It affects about 1 in 5 children and up to 1 in 10 adults at some point. Blood tests for eczema are also common, especially when allergies are suspected as a trigger.

Eczema can start in infancy and often improves with age. It affects people of all ethnicities and genders. Those with a personal or family history of allergies, asthma, or hay fever are more likely to have eczema.

Symptoms

Common symptoms

• Dry, itchy, red or darker areas of skin
• Rough, scaly patches, often on the face, elbows, or knees in children; on hands, eyelids, or backs of knees in adults
• Itching that can be severe, especially at night
• Skin that may ooze clear fluid or form crusts when scratched

Symptoms in children

• Patches often appear on the face, scalp, elbows, and knees
• Intense itching that can disrupt sleep
• Irritability, fussiness, and scratching that can lead to skin infections

Symptoms in older adults

• Very dry, thickened, and intensely itchy skin
• Eczema often appears on the hands, feet, shins, and around the eyes or nipples
• A higher risk of skin infections because of thinner, drier skin and longer healing time

Causes

Main causes

• Eczema is largely genetic—it runs in families and is linked to a protein called filaggrin that helps keep the skin barrier strong.
• The immune system overreacts to triggers, causing inflammation and itching.
• Triggers vary by person and can include dry skin, irritants (soap, wool, smoke), stress, and allergens (dust mites, pet dander, certain foods).

Risk factors

• Family history of eczema, allergies, asthma, or hay fever
• Living in a cold, dry climate or urban area with more pollution
• Exposure to certain irritants, such as harsh soaps or chemicals at work

When to see a doctor

See a doctor urgently if:

• Rash that suddenly becomes very painful, swollen, or starts to spread rapidly with red streaks
• Fever higher than 38°C (100.4°F) along with a rash
• Signs of a severe allergic reaction: hives, difficulty breathing, or faintness

Book a routine appointment if:

• Eczema that does not improve with basic moisturisers and gentle skin care
• Itching that disrupts sleep or daily life
• You want to explore possible allergy triggers through blood testing
• Eczema that appears in new areas or worsens after starting a new medicine or food

Diagnosis

Eczema is primarily diagnosed through a physical exam and talking about your symptoms, medical history, and family history. A doctor will look at your skin, ask about itching, and check for signs of other conditions. A blood test is not needed to make the diagnosis, but it may be used to check for allergies or rule out other problems.

Tests that may be done

• Blood test for total IgE (immunoglobulin E) levels—high levels can suggest an allergic tendency.
• Specific IgE blood test (sometimes called RAST) to check for reactions to individual allergens, like pollen, dust mites, or certain foods.
• Skin prick test (not a blood test)—small amounts of allergens are placed on the skin to see if a reaction occurs.

What to expect at your appointment

The blood test is a simple procedure. A healthcare professional will take a small sample from a vein in your arm, usually in a clinic or lab. It takes a few minutes and may feel like a quick pinch. You can resume normal activities right away. Results may take a few days to a week. Your doctor will explain what the results mean and how they relate to your eczema.

Treatment

Treatment for eczema focuses on keeping the skin hydrated, controlling itching, and avoiding triggers. There is no cure, but many people can manage their symptoms well with a combination of good skin care and medical treatments. A blood test can help guide treatment by identifying specific allergens to avoid.

Self-care at home

• Moisturise daily with fragrance-free creams or ointments, especially after bathing
• Use lukewarm water for baths and pat skin dry—don't rub
• Wear soft, breathable fabrics like cotton and avoid wool or synthetic fibres
• Keep nails short and consider wearing cotton gloves at night to reduce scratching
• Identify and avoid personal triggers, such as certain soaps, detergents, or foods

Medical treatments

Doctors may recommend treatments such as topical corticosteroids (creams or ointments that reduce inflammation) or other prescription creams, including calcineurin inhibitors. For more severe eczema, treatments like phototherapy (controlled exposure to UV light) or systemic medications that adjust the immune system may be considered. Always follow your healthcare provider’s advice—never use stronger treatments without a prescription.

When is surgery considered?

Surgery is not used to treat eczema. In very rare cases, if a skin infection leads to an abscess, a small drainage procedure may be needed, but this is for the infection, not the eczema itself.

Living with this condition

Living with eczema means being mindful of your skin daily. Establish a routine of gentle cleansing and moisturising. Avoid long, hot showers or baths. When scratching is hard to resist, try applying a cool compress or using a moisturizer. Keep your home environment comfortable—not too dry or hot. If you have known allergies, try to limit exposure to triggers like dust mites or pet dander.

Lifestyle tips

• Use mild, fragrance-free soaps, shampoos, and laundry detergents
• Manage stress through relaxation techniques, exercise, or hobbies—stress can flare eczema
• Humidify dry rooms, especially in winter, but keep humidity moderate to prevent dust mites
• Protect skin in cold weather with scarves and gloves, and in hot weather with light clothing and sunscreen

Diet and exercise

There is no special diet for eczema, but some people find that certain foods (like milk, eggs, or nuts) make their eczema worse. A blood test for food allergies can help identify these triggers. Staying active is good for overall health and stress reduction—just shower and moisturise after sweating to avoid irritation.

Mental health and emotional wellbeing

Eczema can be frustrating and embarrassing, especially when it affects visible areas. Itching and sleep problems can lead to anxiety, irritability, or low mood. It’s important to talk to your doctor if you’re feeling down. Support from family and friends, and connecting with others who have eczema, can also help. If you ever feel overwhelmed, reach out to a mental health professional.

Prevention

Eczema itself cannot be prevented because it is largely genetic. But you may be able to reduce the severity of flares by identifying and avoiding your triggers. Keeping the skin well-moisturised from an early age might help delay or reduce symptoms in some children, but this is not guaranteed.

Screening programmes

There is no routine screening test for eczema. Blood tests for allergies are only done if you have symptoms that suggest a trigger. General allergy screening is not recommended for everyone with eczema.

Complications

If left untreated

• Skin infections (bacterial or viral) from constant scratching, such as impetigo or eczema herpeticum
• Long-term skin changes like thickening, darkening, or scarring
• Sleep problems, fatigue, and reduced quality of life from chronic itching
• Emotional distress, including anxiety and depression, especially in severe or visible cases

Long-term outlook

Most people with eczema see improvement as they get older, especially children. With good skin care and the right medical support, the condition can be well controlled. Even if you have eczema for life, you can lead a full and active life. Blood tests and other tools help you and your doctor make informed choices.

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