Management of Hypersensitivity Reactions to Nondextran Iron Products: New Insights Into Predisposing Risk Factors.

Background: Hypersensitivity reactions (HSRs) to nondextran iron products (NDIPs) are rare, but can manifest with severe signs and symptoms. Predisposing risk factors are not well understood.

Objective: To characterize patients with HSRs to NDIPs, with a special focus on possible risk factors.

Methods: We analyzed clinical characteristics of patients with HSRs to NDIPs referred to our allergy division between 2007 and 2019 compared with tolerant controls, including the type of the eliciting NDIP, severity and characteristics of the HSR, atopy status, history of allergies and urticaria, laboratory and skin test results, and outcome of reexposure with NDIPs.

Results: We evaluated the data of 59 patients and 21 controls. Sixteen patients and 4 controls received the NDIP iron sucrose and 41 patients and 15 controls received ferric carboxymaltose. In 2 patients and in 2 controls, the culprit NDIP was not known. Twenty-seven patients (46%) experienced an anaphylactic reaction grade I, 15 (25%) a grade II reaction, and 17 (29%) a grade III reaction according to Ring and Messmer. On analyzing the history, we found that 22 patients (37%) and 3 controls (14%) reported previous HSRs to other medications. Interestingly, more than half the patients (n = 35 [59%]) compared with only 7 controls (33%) reported an episode of any type of urticaria in their previous history. Most patients (n = 15 [79%]) tolerated reexposure of an NDIP using a low-reactogenic administration protocol.

Conclusions: A history of drug hypersensitivity and urticaria represent potential risk factors for HSRs to NDIPs. On the basis of our findings, we propose an algorithm for practical management of patients receiving NDIPs aiming to prevent HSRs.