Eczema is diagnosed through a physical examination and a patch test. The allergens identified by the patch test should be thoroughly examined by dermatologists, and a definitive diagnosis should be established based on these evaluations.

During the patch test, low concentrations of potential allergens are applied to the patient's back and observed for possible reactions after 48 to 72 hours. During this period, it is crucial to avoid physical activities such as sports or showering that could affect the test results. If symptoms like blistering, weeping, or redness are observed in the application area, it is determined that the patient is showing an allergic eczema reaction to the respective substance.