Contact dermatitis manifests as a red area that often itches or stings. Blisters and skin sores may also develop. Most commonly, contact dermatitis occurs on the hands, but it can also occur in other areas of the body. Approximately 5% of the population experiences episodes of contact dermatitis during their lifetime.
There are two types of contact dermatitis: allergic contact dermatitis and irritant contact dermatitis.
Allergic contact dermatitis is a delayed type of hypersensitivity, and symptoms appear 24 to 72 hours after exposure to the allergen. This type of dermatitis is often well-defined and improves within a few days.
In irritant contact dermatitis, the rash can appear anywhere from a few minutes to a few hours after exposure to the irritating substance. If it is a mild irritation, the reaction may not become evident until days or weeks after the exposure. This form of dermatitis is typically less well-defined, and it can take several weeks to improve.
The triggering factors for contact dermatitis can vary widely. Some examples include nickel, cobalt, and chromium, rubber chemicals, perfumes, and plants. The toxic variant is often related to occupational exposure and can be triggered by various chemicals and liquids.