Drug allergy in clinical practice

Adverse reactions to pharmacologic agents are becoming more and more common as more drugs are administered to sicker patients. Allergic (immunologic) reactions are difficult to distinguish from idiosyncratic (nonimmunologic) reactions, and reactions that appear to be similar may have entirely different etiologies. Diagnosis of an adverse reaction and identification of its cause require an index of suspicion, familiarity with the drugs being used, knowledge of common reactions to these drugs, and occasionally, challenge with the suspected drug. Specific diagnosis often obviates unnecessary discontinuance of an effective drug.