Contact Dermatitis

Contact dermatitis is inflammation caused by something touching the skin. The two major forms can look similar, but they develop for different reasons. Allergic contact dermatitis (ACD) is a delayed type IV hypersensitivity reaction. During an initial exposure, the immune system becomes sensitized to an allergen. On later contact, sensitized T-cells recognize that allergen and drive inflammation. The delay matters: a patient may not connect a rash that appears hours or days later with a product, plant, adhesive, or metal encountered earlier. Irritant contact dermatitis (ICD) does not require sensitization. Repeated or prolonged contact with an irritant directly damages epidermal cells and disrupts the stratum corneum lipid barrier. Water escapes through the damaged barrier, the skin becomes dry and fissured, and inflammation follows. Frequent handwashing, wet work, detergents, sanitizers, and chemicals are common contributors. The experienced nurse first looks at the rash’s shape and distribution. Contact dermatitis often traces the exposure: hands after repeated wet work, earlobes beneath jewellery, a sharply outlined patch under an adhesive, or linear streaks after brushing against a plant. That geometry is a clinical clue...