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Diagnosis of drug allergy is quite complicated given myriad symptoms and clinical presentations associated with the condition, and usually begins with an extensive medical history.1,2
Evaluation of the patient with a suspected drug allergy should include a detailed history of all drugs taken by the patient, including:2
The diagnosis of drug allergy is based on a detailed history of the onset of symptoms and signs that are compatible with drug-induced allergic reactions.2
To facilitate the recording of an appropriate history, a questionnaire has been developed that might provide a guide in this rather difficult area of clinical medicine.6
Depending on the history and physical examination results, carefully selected diagnostic tests including specific IgE tests may be required.2
Healthcare providers should evaluate for drug allergy when there is a history of prior ADRs and the drug is required without an equally effective, structurally unrelated alternative, and if the risk/possible benefit ratio is positive or when there is a history of severe ADRs for other drugs.4
Drug hypersensitivity reactions are most common in patients over 50 years of age and up to 70 percent of patients suspected of having an allergic reaction to drugs are women.1
Penicillin is the most frequent drug allergy, affecting approximately 10 percent of patients.2 Five percent of the population have allergic reactions to penicillin and other β-lactam antibiotics.1
Other common allergens include:2
Adding diagnostic testing to aid in a differential diagnosis has been shown to increase confidence in diagnosis to 90 percent.i,ii Conventionally, a diagnosis of allergic or autoimmune disease relies on the case history and a physical examination. However, adding diagnostic testing to aid in a differential diagnosis has been shown to increase confidence in diagnosis.i,ii Diagnostic testing can also help to improve the patient’s quality of life and productivity, reduce costs associated with absenteeism, and optimize use of medication, in addition to decreasing unscheduled healthcare visits.iii,iv
i. Duran-Tauleria E, Vignati G, Guedan MJ, et al. The utility of specific immunoglobulin E measurements in primary care. Allergy. 2004;59 (Suppl78):35-41.
ii. NiggemannB, Nilsson M, Friedrichs F. Paediatric allergy diagnosis in primary care is improved by in vitro allergen specific IgE testing. Pediatr Allergy Immunol. 2008;19:325-331
iii. Welsh N, et al. The Benefits of Specific Immunoglobulin E Testing in the Primary Care Setting. J Am Pharm Assoc. 2006;46:627.
iv. Szeinbach SL, Williams B, Muntendam P, et al. Identification of allergic disease among users of antihistamines. J Manag Care Pharm. 2004; 10 (3): 234-238
The most effective strategy for the management of drug allergy are:1,2,4
When available, alternative medications with unrelated chemical structures should be substituted.2
Prevention of future adverse drug reactions is an essential part of patient management. Healthcare providers often provide the patient with written information about which drugs to avoid, including any over-the-counter (OTC) medications.2 Engraved allergy medical bracelets and necklaces may also be considered, particularly if the patient has a history of severe reactions.2
Practice parameters have been developed to help guide the management and treatment of patients with drug allergies.