RAST testing is a term that is often used to describe blood test for allergy (although most currently used blood tests for allergy are no longer truly a RAST test), while skin testing involves plastic needles that are used to prick the skin of the patient. RAST testing is sometimes a reasonable alternative when a patient cannot stop antihistamines. RAST stands for ‘radioallergosorbent test’ and measures the amount of IgE antibody in the blood — the antibody involved in allergies. Due to improved laboratory techniques, the radioallergosorbent test is no longer performed. The newer laboratory techniques more accurately measure allergy antibody levels than the old RAST testing.