Drug allergy encompasses a spectrum of immunologically-mediated
hypersensitivity reactions with varying mechanisms and clinical presentations. This type of
adverse drug reaction (ADR) not only affects patient quality of life, but may also lead to
delayed treatment, unnecessary investigations, and even mortality. Given the myriad of symptoms associated with the condition, diagnosis is often challenging. Therefore, referral to an allergist experienced in the identification, diagnosis and management of
drug allergy is recommended if a
drug-induced
allergic reaction is suspected. Diagnosis relies on a careful history and physical examination. In some instances, skin testing, graded challenges and induction of drug tolerance procedures may be required.The most effective strategy for the management of
drug allergy is avoidance or discontinuation of the offending
drug. When available, alternative medications with unrelated chemical structures should be substituted. Cross-reactivity among drugs should be taken into consideration when choosing alternative agents. Additional
therapy for
drug hypersensitivity reactions is largely supportive and may include topical
corticosteroids, oral
antihistamines and, in severe cases, systemic
corticosteroids. In the event of
anaphylaxis, the treatment of choice is
injectable epinephrine. If a particular
drug to which the patient is allergic is indicated and there is no suitable alternative, induction of drug tolerance procedures may be considered to induce temporary tolerance to the
drug.This article provides a backgrounder on
drug allergy and strategies for the diagnosis and management of some of the most common
drug-induced
allergic reactions, such
allergies to
penicillin,
sulfonamides,
cephalosporins,
radiocontrast media,
local anesthetics,
general anesthetics,
acetylsalicylic acid (ASA) and non-steroidal anti-inflammatory drugs.