If you have persistent dry, itchy, scaly skin, you may have eczema. This common skin condition isn’t contagious, so there’s no concern about spreading it to others. Effective treatments are available to reduce symptoms and improve your quality of life. Schedule an appointment with your health care provider to get an accurate diagnosis.

How Does a Doctor Diagnose Eczema?

An eczema diagnosis is usually straightforward. It rarely requires lab tests and can often be diagnosed during an office visit with a primary care physician, a dermatologist, or an allergist. If your child has symptoms, their pediatrician should be able to help.

There isn’t a standard diagnostic test for eczema. If you ask your health care provider how to diagnose eczema, they’ll likely recommend a physical exam and a medical and family history. In some cases, they may order blood tests, allergy tests, or skin biopsies to confirm an eczema diagnosis or rule out other skin conditions with similar symptoms.

1. Medical History

Your health care provider will start by taking a thorough history, asking about your symptoms over time, your family medical history, and any exposures you’ve had to potential irritants or irritants.

They might ask questions such as these:

• Where on your body do you have symptoms?
• What kind of symptoms do you experience?
• How often do you experience these symptoms?
• When did the symptoms start?
• Have you made any recent changes to your skin care products or routine?
• Have you noticed if certain soaps, lotions, or detergents make your symptoms worse?
• Do you have any medical conditions like allergies or asthma?
• Does anyone in your family have eczema or another skin condition?

A clear picture may emerge from your medical history. Your answers will help your health care provider assess risk factors that may strengthen the suspicion of eczema or rule out other conditions, including skin infections. If you or others in your family have asthma, food allergies, or hay fever, you’re more likely to develop eczema.

To help your health care provider make an accurate diagnosis, take notes when you have flare-ups so you can describe your symptoms in detail during your next appointment.

2. Physical Exam

After discussing your medical history, your doctor will likely perform a physical exam. During this process, they’ll evaluate your skin for signs of eczema and other skin diseases or illnesses that may mimic its symptoms.

Common eczema symptoms include:

• Dry skin
• Rash
• Itchy skin
• Scaly, crusty, or flaky areas
• Blisters or lesions
• Thick or swollen skin
• Skin that’s raw from scratching

There are many types of eczema, and symptoms can vary by type. The most common type is atopic dermatitis. Some eczema or atopic dermatitis symptoms can vary by skin tone. On lighter skin, an eczema rash might appear red, pink, or purple. On darker skin, it could look brown, purple, or gray with small, raised bumps. Your doctor will consider these factors during the physical exam.

If the medical history and physical exam provide enough information for your doctor to be confident that you have eczema, they’ll likely confirm the diagnosis without additional tests. Otherwise, the diagnostic process will continue.

3. Skin Tests

A health care provider may perform two types of skin testing if they suspect you have eczema. The first and most common is a patch test.

Patch Test

In patch testing, one or more small patches are placed on your skin during an office visit. You’ll return to the doctor’s office 48 hours after the patch test is placed for the first reading and then 48 hours later for a delayed reading. Patch testing can be used to confirm a diagnosis of contact dermatitis, which is a specific type of eczema. The test can help identify substances that trigger contact dermatitis.

Skin Biopsy

In rare cases, a doctor may perform a skin biopsy — removing a tiny piece of skin for laboratory examination. Usually, a punch biopsy is performed to confirm the diagnosis. During a punch biopsy, a doctor uses a round-tipped tool to “punch” through layers of the skin and get a sample.

4. Blood Test

If your doctor suspects an allergic reaction is causing your symptoms, they may recommend a blood test for eczema. The allergen-specific immunoglobulin E (IgE) test — also called the radioallergosorbent test (RAST) or ImmunoCap test — measures the IgE levels in your blood that react to the allergen. Blood testing is much less reliable than skin testing because it produces many false positives — results often mistakenly indicate that an allergy exists.

If your doctor suspects that a food allergy is causing your rash, they may recommend you undergo allergy testing. However, some researchers and doctors recommend not testing for food and environmental allergies because false positives can lead to unnecessary lifestyle changes. You can always ask your health care provider why they recommend a specific test and what they hope to discover.

Ruling Out Other Conditions

Other conditions can produce symptoms like those of eczema. The process of ruling out similar conditions is referred to as an eczema differential diagnosis. Conditions that can mimic symptoms of eczema include:

• Food allergy
• Psoriasis
• Bacterial infections, such as impetigo
• Fungal infections, such as candida (yeast infection) or tinea (ringworm)
• Viral infections, such as molluscum contagiosum
• Infestations, such as scabies
• Cystic fibrosis
• Reaction to a medication
• Dermatitis herpetiformis, a condition related to gluten sensitivity

Your health care provider may be able to quickly rule out many of these conditions based on your medical and family history or simple blood tests. Other disorders may require time and repeated tests before they can be confirmed or ruled out. The presence of other conditions in addition to eczema may complicate the diagnostic process and eventually result in multiple diagnoses. The best way to test if you have eczema or find out what is causing eczema is to schedule an appointment with your health care provider. The sooner you get a diagnosis, the sooner you and your doctor can come up with a treatment plan to help you feel better.

Find Your Team

On MyEczemaTeam, the social network for people with eczema and their loved ones, more than 54,000 members come together to ask questions, give advice, and share their stories with others who understand life with eczema. When managing eczema, joining a support group and talking about your experiences may be helpful.

Have you or a loved one been diagnosed with eczema? What was the process like for you? Share your experience in the comments below, start a conversation by posting on your Activities page, or connect with like-minded members in Groups.