What is the primary characteristic of contact dermatitis?

The primary characteristic of contact dermatitis is that it is a reaction from a substance. This condition occurs when the skin comes into direct contact with an irritant or allergen. This can result from many potential sources, including chemicals in personal care products, certain metals, plants like poison ivy, or even fabrics. The skin reacts to these substances, leading to inflammation, redness, itching, and sometimes blistering, depending on the sensitivity of the individual and the nature of the substance involved.

Understanding this core aspect is important for recognizing and managing contact dermatitis effectively. The other options, while they may touch on related points, do not capture the fundamental essence of the disorder. For instance, while some contact dermatitis does stem from allergic reactions, not all cases are allergic in nature; they may also arise from irritation without an immune response. Additionally, contact dermatitis can affect individuals of all ages, including adults and seniors, not just children. Lastly, although genetic predispositions may influence skin reactions, the condition specifically results from direct contact with a triggering substance rather than solely genetic factors.