Allergic dermatitis is a common skin disease, which is an inflammatory skin disease caused by contact with allergens. So, is allergic dermatitis contagious? It is not contagious. This disease can cause itchy skin, formation of vesicles or papules, redness, or swelling. Once symptoms appear, it is recommended to treat with anti-allergic medication. Also, it is important to avoid contact with allergens again, eat a light diet, and ensure adequate rest.