Allergic Contact Dermatitis is a delayed hypersensitivity reaction after one or a few exposures to an antigenic substance. For example, a substance like Nickel in costume jewelry, penetrates the skin and sensitizes the body to it’s chemical structure. Once re-exposed, one develops an allergic reaction with inflammation, oozing and scaling at that site. A person can be allergic to many different chemicals. Many South Florida residents are allergic to poison ivy and mango trees. Patients allergic to poison ivy may develop a diffuse rash or itching following the ingestion of raw cashew nuts. This is due to the fact that raw cashew nut oil is chemically related to both mango sap & poison ivy.