What best describes allergic contact dermatitis?

Allergic contact dermatitis is best described as an allergy that occurs when the skin comes into repeated contact with a specific allergen, leading to an inflammatory reaction. In this condition, the immune system identifies a normally harmless substance as a threat, resulting in symptoms such as redness, itching, and swelling at the site of contact. This can occur from various substances, such as certain metals in jewelry, chemicals in cosmetics, or ingredients in personal care products. Recognizing the role of repeated exposure is crucial, as the condition often develops over time after sensitization to the allergen.

The other options describe different skin issues or conditions that do not directly relate to the nature of allergic contact dermatitis. A chronic skin infection typically involves pathogens and ongoing inflammation, while poor hygiene is associated with a range of skin problems, and environmental factors usually lead to irritation rather than an allergic response.