Contact dermatitis is a skin rash that results from contact with a substance that causes an allergic reaction. Or it can occur from contact with a substance that irritates the skin. A minor reaction may cause mild redness of the skin, itching, or a rash of small red bumps. A more severe reaction may cause pain, swelling, redness, and larger blisters.
Many things can cause contact dermatitis, including soaps, lotions, latex gloves, and plants such as poison ivy. The location of the rash may provide a clue about the cause.