Abstract
Drug skin tests can be helpful in determining the cause of a cutaneous adverse drug reaction (CADR). Patch tests and prick tests can be performed with any commercialized form of a drug. Intradermal tests (IDTs) have a greater value, but their techniques have not been standardized. Moreover, IDTs can be done only if an injectable form of the drug is commercialized and are restricted to patients with nonsevere CADR. Prick tests and IDTs are used in investigating immediate hypersensitivity. Patch tests both with IDTs with delayed readings are helpful for maculopapular rash and generalized or localized eczema. Results obtained with drug skin tests in β-lactam sensitization have been extensively published, but fortunately, during the last few years the value of skin tests in CADR due to other drug classes (e.g., synergistins, platinium salts or radiocontrast medias) was also studied. The analysis of recent literature permits to propose which tests to choose for each clinical feature of CADR and to give the list of all drugs, having had patch tests with positive results but, emphasizes the lack of standardization in performing and reading IDTs. This standardization is absolutely necessary to determine the thresholds of specificity of the IDT. Except for IDTs, drug skin tests induce only rarely adverse reactions. False-positive results can occur and should be considered by testing new products. The negative predictive value of drug skin tests is a crucial point that will have to be studied in more detail in the near future.
Financial disclosure
The author has no relevant financial interests related to this manuscript, including employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.