Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School



Before allergy shots can be given, you must have tests to determine which allergens are causing your allergic reactions. These tests can include skin or patch testing or a blood test called a radioallergosorbent test (RAST). The tests are a useful guide, but they are not always accurate, so you can have a positive test with no allergy symptoms or a negative test and still have allergy symptoms.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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