Patients can undergo testing to find out what allergens and irritants are worsening their symptoms. Know what triggers your eczema puts you one step closer to reducing symptoms, whether through avoidance, medication or other treatments.
Skin Prick Tests
Droplets of suspected allergens are placed on or just under the skin surface. Raised bumps (about the size of a mosquito bite) strongly indicate an allergy to the substance. Skin prick testing is commonly used by allergists because of its accuracy, ease of use and immediate results. Results are typically known within 20 minutes.
Blood Test
After a blood sample is drawn, it is analyzed to detect IgE antibodies directed at specific allergens. Tests may measure specific or overall levels of IgE Some may also break down common allergens and measure IgE to specific components. Lab results may take several days. Consult with your doctor to ensure that the blood test is interpreted correctly. Eczema typically results in very high IgE levels and may falsely elevate results.
Patch Test
Chambers containing chemicals of potential triggers on adhesive strips are placed on the patient’s back. After 2-3 days, the patches are removed by the doctor and the skin is evaluated for reactions. If symptoms appear, then it’s confirmation of an allergy. Patch testing is commonly used for contact allergies to fragrances, detergents, metal and other chemical substances.
Oral Food Challenge
If it’s believed that a food allergy is causing symptoms, the doctor may want to perform an oral food challenge. In this test, the patient is asked to eat a tiny amount of a suspected allergen, and then gradually larger amounts, to determine if there’s an allergic reaction. The challenge should only be conducted by a doctor and at a medical facility that has access to epinephrine and other emergency treatments.
Other tests helpful in diagnosing eczema
Buccal swabs
Buccal swabs, or cheek swabs, are used to detect mutations in the filaggrin gene, the protein that helps protect the body from allergens and bacteria; a lack of filaggrin weakens the skin barrier, leading to eczema.
Skin biopsy
A skin biopsy, where a tiny piece of skin is removed and analyzed under a microscope, can rule out other skin diseases such as skin cancer or psoriasis.
After testing, your doctor will compile all of the evidence together – test results, your personal and family health history, physical exam, home and work environments, activities that might expose you to allergens – to reach a diagnosis.
© 2021 Allergy and Asthma Network
Last updated : 2/6/2023