Urticaria or hives is a relatively common form of allergic reaction that causes raised red skin welts that range upwards from 5 mm (about a 1/4 inch) in diameter, itch severely, and often have a pale border. Urticaria is caused by direct contact with an allergenic substance (generally a plant, such as poison ivy), or an immune response to food or some other allergen. Hives can also be caused by stress.

Dermatitis, also known as eczema, is a skin irritation characterized by red, flaky skin, sometimes with cracks or tiny blisters. Dermatitis is extremely itchy, but scratching damages the fragile skin and exacerbates the problem so it is important for people with eczema to try to leave the area alone.