Allergic dermatitis is a skin condition caused by an allergic reaction when the skin comes into contact with certain substances such as cosmetics, metals, chemicals, plants, or fabrics. It often results in symptoms like redness, itching, swelling, rashes, dryness, or blistering in the affected area. The reaction occurs when the immune system responds to an allergen, sometimes even after repeated exposure. Management includes identifying and avoiding the triggering substance, soothing the skin with appropriate treatments, and seeking medical care when symptoms are severe or persistent to promote healthy skin recovery.