How is eczema diagnosed?

To diagnose eczema, doctors rely on a thorough physical examination of the skin as well as the patient's account of the history of the condition. In particular, the doctor will ask when the condition appeared, if the condition is associated with any changes in environment or contact with certain materials, and whether it is aggravated in any specific situations. Eczema may have a similar appearance to other diseases of the skin, so the diagnosis is not always simple. In some cases, a biopsy of the skin may be taken in order to rule out other skin diseases that may be producing signs and symptoms similar to eczema. If a doctor suspects that a patient has allergic contact dermatitis, allergy tests, possibly including a skin "patch test," may be carried out in an attempt to identify the specific trigger of the condition.

There are no laboratory or blood tests that can be used to establish the diagnosis of eczema.