Diagnosing eczema often involves the personal history, family history, and examination of the rash. The doctor is likely to be interested in knowing how long the person has had the rash, the symptoms of the rash, and any personal history of rashes. Since eczema runs in families, diagnosing eczema includes knowing the family history of the individual.

The tendency to have eczema is a genetic oversensitivity of the immune system. People with eczema may have a personal or family history of eczema, asthma, or allergies. This hereditary tendency towards these diseases is called atopy. Though it may seem strange if someone goes to the doctor for a rash and the doctor asks about asthma and allergies, there is good reason for the doctor to know the person’s family and personal history of these conditions.

A visual diagnosis of eczema starts with the location of the rash. Atopic dermatitis, the most common form of eczema, usually occurs on the inside folds of the knees and elbows. The visual diagnosis of eczema will also include examining the characteristics of the rash. If the rash is dry, bumpy, or scaly, it may be atopic dermatitis.

If a rash has a different appearance that does not mean that it is not eczema. Different types of eczema have different appearances. Most eczema rashes have dry, flaky skin but some may develop weeping sores. In some severe cases, the doctor may need to take a sample to be tested at the laboratory, but testing for eczema is rare. However, eczema rashes have the ability to become infected and serious.

The doctor may also want to know if the rash tends to disappear and reappear. Eczema often comes and goes. Once diagnosed, the doctor may give information to the patient on how to reduce the frequency of flare-ups. If the person has a history of previous rashes, dry skin, or sensitive skin, the doctor should be made aware of these tendencies. Many people with eczema have these characteristics.

The doctor should know any medications or treatments that the patient has used to try to treat the rash. Even after eczema is diagnosed, the doctor may want to have periodic examinations to check to rash when the person has a flare-up. The doctor may give the person guidelines for when they should contact the doctor, especially if prescription medication is given to treat the eczema. Once eczema is diagnosed, the doctor may discuss treatment options and ways to prevent flare-ups.