Drug allergy screening

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Charmaine Patel, M.D. [2]

Drug Allergy

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Overview

In general, screening for drug allergies is discouraged. To screen for drug allergy, one would have to be exposed to the drug, which may mean putting the individual at an uneccesary risk for a severe drug reaction through a screening test. Screening for drug allergy may be useful in patients who are in need of a specific medication, but are susceptible or carry risk factors for having a severe allergic reaction upon exposure to the drug. Testing is usually reserved as a confirmatory diagnostic test in individuals who have already been shown to have an allergic reaction to a drug.

Screening

Neither allergy blood testing nor skin testing should be used for primary screening measures in healthy patients: they may be most useful as confirmatory tests when the patient’s history is compatible with an IgE-mediated reaction, and the patient is in need of a specific medication that carries the risk of inducing a severe reaction.

  • Skin prick testing (SPT) and intradermal testing (a test where a small amount of allergen is injected into the dermal layer of the skin) are useful for predicting an allergic reaction mediated by IgE-mediated reactions (type I hypersensitivity). Skin testing protocols are standardized for drugs such as penicillin, and are also useful (but rarely positive) for local anesthetics,muscle relaxants, and very sensitive for high-molecular-weight protein substances such as insulin and monoclonal antibodies. Positive skin tests to these drugs confirm the presence of antigen-specific IgE, and supports the diagnosis of a type I hypersensitivity reaction. [1] The negative predictive value of penicillin skin testing is high, and therefore, a negative test is useful for ruling out a penicillin allergy.
  • IgE Blood tests that measure levels of IgE against specific drug allergens, can confirm an allergic disorder. They are useful when skin testing cannot or should not be performed. The likelihood of an IgE-mediated clinical reaction often increases with the level of specific IgE, but these levels do not predict severity or guarantee a reaction will occur. In the appropriate setting, these tests can help in identifying specific allergens and assessing allergic disease. [1]

References

  1. 1.0 1.1 Warrington R, Silviu-Dan F (2011). "Drug allergy". Allergy Asthma Clin Immunol. 7 Suppl 1: S10. doi:10.1186/1710-1492-7-S1-S10. PMC 3245433. PMID 22165859.



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