Steroid Allergy: Clinical Features and the Importance of Excipient Testing in a Diagnostic Algorithm

True corticosteroid (CS) allergy is rare. Instead, many patients may be allergic to excipients found in various CS preparations. Excipient testing is frequently overlooked. It might lead to unnecessary CS avoidance or dangerous re-exposure.

The objective of this study was to evaluate the clinical characteristics and frequency of excipient allergy in patients with confirmed type I hypersensitivity to systemic CS preparations.

Patients with a confirmed diagnosis of allergy (positive skin test or drug provocation test [DPT]) or tolerance (negative DPT to CS) over the past 10 years were studied. Patient characteristics, index CS, route of administration, clinical indications, symptoms of index reaction, and outcomes of CS/excipient allergy testing were analyzed.

Sixty-four patients underwent CS allergy testing. True CS allergy was confirmed in 9 of 64 (14%) patients. The majority (5/9, 56%) with positive skin tests or DPT were actually allergic to the excipients (2 to carboxymethylcellulose and 3 to polyethylene glycol) rather than the CS. Respiratory manifestations were significantly associated with confirmed allergy (odds ratio = 6.79 [95% confidence interval = 1.36-34.03], P = .02).

Patients with respiratory manifestations were significantly more likely to be truly allergic. CS allergies are rare and may be overdiagnosed without excipient testing. We suggest the use of Carmellose eye drops as a readily available source of carboxymethylcellulose for testing and propose a comprehensive diagnostic algorithm for suspected CS allergy.