Drug provocation testing for eperisone-induced immediate hypersensitivity: A case series and proposal of a risk-stratified approach
Ji Hyun Oh, Hee-Kyoo Kim, Gil-Soon ChoiBackground:
Eperisone hydrochloride is a widely used muscle relaxant; however, its potential to cause immediate hypersensitivity is often overlooked because of its frequent coadministration with nonsteroidal anti-inflammatory drugs (NSAIDs). We aimed to describe the clinical characteristics and drug provocation test (DPT) outcomes of eperisone-induced immediate hypersensitivity and to explore a pragmatic, risk-based approach based on our clinical experience.
Methods:
Between 2020 and 2025, we retrospectively analyzed 17 patients with suspected eperisone-induced immediate hypersensitivity. Clinical characteristics, skin prick test, intradermal test, and DPT results were evaluated. Reaction severity was graded using the 2020 World Allergy Organization (WAO) 5-grade systemic allergic reaction grading system.
Results:
Eperisone hypersensitivity was confirmed in 13 (76.5%) patients using DPT. All confirmed patients had negative skin prick tests, and only 1 showed a marginal intradermal reaction at the highest concentration (10 mg/mL). During DPT, 84.6% reacted at or before the second dose-escalation step. Hypersensitivity was elicited at remarkably low doses (9.37–50 mg), with severe anaphylaxis occurring at doses as low as 9.37 mg (1/8 tablet), and symptom onset occurring within 35 minutes of the last administered dose in most cases (76.9%). A total of 61.5% of confirmed patients experienced grade 3-5 reactions consistent with anaphylaxis; delate 30.8% developed grade 5 reactions, and 23.1% required repeated epinephrine administration. Although severity did not differ between formulation, sustained-release preparations were associated with delayed or prolonged reactions in some cases.
Conclusion:
Skin tests have limited diagnostic value for eperisone hypersensitivity. When immediate hypersensitivity occurs in the setting of concomitant NSAID use, eperisone should be actively considered as a potential culprit rather than attributing the reaction solely to NSAIDs. Because severe reactions may occur even at very low doses during DPT, it should be reserved for carefully selected patients in whom the anticipated diagnostic benefit outweighs the procedural risk, with individualized risk-reduction strategies when clinically indicated.