Contact dermatitis occurs when a person is exposed to a substance that irritates the skin or triggers an allergic reaction, as stated by Mayo Clinic. There are two main types of contact dermatitis: irritant contact dermatitis and allergic contact dermatitis.
Irritant contact dermatitis is the more common of the two types of skin irritations, notes Mayo Clinic. It occurs when a substance damages the skin's outer protective layer. Some everyday irritants are solvents, rubbing alcohol, bleach, soaps, deodorants and certain types of cosmetics. Allergic contact dermatitis occurs when a substance triggers a sensitivity to the immune reaction in the skin. Examples of allergens that cause contact dermatitis are nickel, airborne substances, such as aromatherapy and spray insecticides, and formaldehyde.