This itchy skin condition, caused by a reaction to agents that come in contact with the skin, occurs after the immune system processes the absorbed material and mounts an immune response against it.
The skin reaction results in severe itching, swelling and redness in the affected area. The first reaction may be delayed in appearance, but future exposure to the agent responsible will cause reactions to appear within 24 hours.
Prescription medications are often necessary to control the process. Poison ivy is a classic example of Allergic Contact Dermatitis. For mild cases topical prescription medications are used to control the process. If the problem is widespread, oral prednisone may be needed.