Contact dermatitis is inflammation of the skin caused by contact
with a substance that causes an allergic reaction. A minor case of contact
dermatitis may cause mild redness of the skin or a rash of small red bumps,
while a more severe reaction may cause swelling, redness, and larger blisters.
A rash usually starts about 48 hours after exposure to the
irritating substance. Common causes of contact dermatitis include:
- Poisonous plants, such as poison ivy, oak, or
sumac.
- Soaps, detergents, shampoos, perfumes, cosmetics, or
lotions.
- Jewelry or fabrics.
- New tools, toys,
appliances, or other objects.
- Latex gloves.
The location of the rash may provide a clue about the cause.
Contact dermatitis does not usually occur with the first exposure
to the irritating substance (allergen). After a reaction to the substance
occurs for the first time, a rash can occur in response to even very small amounts of the
substance.
