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The terms eczema and dermatitis are used interchangeably, denoting a polymorphic inflammatory reaction pattern involving the epidermis and dermis. There are many etiologies and a wide range of clinical findings. Acute eczema/dermatitis is characterized by pruritus, erythema, and vesiculation. Chronic eczema/dermatitis is characterized by pruritus, xerosis, lichenification, hyperkeratosis/scaling, and ± fissuring.


Contact dermatitis is a generic term applied to acute or chronic inflammatory reactions to substances that come in contact with the skin. Irritant contact dermatitis (ICD) is caused by a chemical irritant. Allergic contact dermatitis (ACD) is caused by an antigen (allergen) that elicits a type IV (cell-mediated or delayed) hypersensitivity reaction.

ICD occurs after a single exposure to the offending agent that is toxic to the skin (e.g., croton oil) and in severe cases may lead to necrosis. It is dependent on concentration of the offending agent and occurs in everyone, depending on the penetrability and thickness of the stratum corneum. There is a threshold concentration for these substances above which they cause acute dermatitis and below which they do not. This sets ICD apart from ACD, which is dependent on sensitization and thus occurs only in sensitized individuals. Depending on the degree of sensitization, minute amounts of the offending agents may elicit a reaction. Since ICD is a toxic phenomenon, it is confined to the area of exposure and is therefore always sharply marginated and never spreads. ACD is an immunologic reaction that tends to involve the surrounding skin (spreading phenomenon) and may spread beyond affected sites.


  • ICD is a localized disease confined to areas exposed to irritants.

  • It is caused by exposure of the skin to chemical or other physical agents that are capable of irritating the skin.

  • Severe irritants cause toxic reactions even after short exposure.

  • Most cases are caused by chronic cumulative exposure to one or more irritants.

  • The hands are the most commonly affected area.


ICD is the most common form of occupational skin disease, accounting for up to 80% of all occupational skin disorders. However, ICD need not be occupational and can occur in anyone being exposed to a substance irritant or toxic to the skin.


ETIOLOGIC AGENTS (Table 2-1) Abrasives, cleaning agents, oxidizing agents; reducing agents, plants, and animal enzymes, secretions; desiccant powders, dust, and soils; excessive exposure to water.

TABLE 2-1Common Irritants


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