Cutaneous hypersensitivity reactions by CI to NSAIDs are the most frequent entities induced by these compounds. In addition to aspirin, other NSAIDs are taking on a predominant role. Atopy can be a predisposing factor in patients with CI.

The sensitivity of Basotest is similar to immunoassays (CAP/RAST). Sensitivity is improved when used in combination. Although further studies are required, Basotest results for cephalosporin allergy seem very promising. This technique does not help differentiate between selective reactors and cross-reactors.

Nonsteroidal anti‐inflammatory drugs (NSAIDs), the medications most commonly used for treating pain and inflammation, are the main triggers of drug hypersensitivity reactions. The latest classification of NSAIDs hypersensitivity by the European Academy of Allergy and Clinical Immunology (EAACI) differentiates between cross‐hypersensitivity reactions (CRs), associated with COX‐1 inhibition, and selective reactions, associated with immunological mechanisms. Three phenotypes fill into the first group: NSAIDs‐exacerbated respiratory disease, NSAIDs‐exacerbated cutaneous disease and NSAIDs‐induced urticaria/angioedema. Two phenotypes fill into the second one: single‐NSAID‐induced urticaria/angioedema/anaphylaxis and single‐NSAID‐induced delayed reactions. Diagnosis of NSAIDs hypersensitivity is hampered by different factors, including the lack of validated in vitro biomarkers and the uselessness of skin tests. The advances achieved over recent years recommend a re‐evaluation of the EAACI classification, as it does not consider other phenotypes such as blended reactions (coexistence of cutaneous and respiratory symptoms) or food‐dependent NSAID‐induced anaphylaxis. In addition, it does not regard the natural evolution of phenotypes and their potential interconversion, the development of tolerance over time or the role of atopy. Here, we address these topics. A state of the art on the underlying mechanisms and on the approaches for biomarkers discovery is also provided, including genetic studies and available information on transcriptomics and metabolomics.

Genetic variants of the AA pathway may play an important role in NSAID-induced AU. These data may help understand the mechanism underlying this disease.