Allergy testing, blood

A blood allergy test, also known as Radioallergosorbent Test (RAST), measures the amount of IgE antibody that your body produces when exposed to common allergens present in dust, pollen, mold, animals, or foods. Blood allergy tests are less sensitive than skin allergy tests but are indicated when antihistamines cannot be discontinued, the patient has severe dermatitis, or is extremely sensitive to allergens. In a blood allergy test, you will have blood taken once. The blood will be sent to the laboratory to test for many allergies at the same time by seeing which allergens you've made IgE antibodies against.