The term eczema, which has been in use since the time of Hippocrates, referred to a skin disease of unknown etiology with a chronic progression, characterized by remissions and flare-ups and presenting with itching, skin inflammation, vesicles, and oozing. With the progress of medical science, the causes of certain forms of eczema were identified, thus introducing the term Dermatitis for them (e.g., irritant, allergic, atopic dermatitis, etc.). In practice, the two terms are used interchangeably today.

In its acute phase, dermatitis is characterized by erythema (redness), edema (swelling), vesicles (small blisters with serous content), and pruritus (itching), gradually leading to rupture (of the vesicles) and weeping (serous discharge). As the condition progresses to the subacute phase, erythema and itching decrease, and crusts (from the dried serous discharge of ruptured vesicles) and scales develop. Finally, in its chronic phase, dermatitis is characterized by lichenified plaques due to thickening of the epidermis caused by chronic scratching/pruritus.