Resident physician Université de Montréal, Quebec, Canada
Background: Intravenous (IV) iron therapy is widely used for the management of iron deficiency, yet adverse reactions remain a concern, particularly in hospitalized patients with comorbidities. This study aimed to describe the incidence, clinical characteristics, predictors, and management of adverse reactions following IV iron administration in a large tertiary care hospital.
METHODS AND RESULTS: We conducted a retrospective observational study including 1,269 perfusion of IV iron at the Centre Hospitalier de l’Université de Montréal (CHUM) between August 2023 and May 2024. Patient demographics, comorbidities, iron formulations, administration protocols, and adverse events were collected. Reactions were categorized as minor or major. Univariable and multivariable analyses were performed to identify predictors of adverse reactions.
Among 1,269 IV iron infusions, 252 (20%) were given to patients with known heart failure. Ferric derisomaltose was used in 993 (78%) infusions, iron sucrose in 143 (11%), and ferric gluconate in 113 (10%). Overall, 110 infusions (8.7%) were associated with at least one adverse reaction within 24 hours. Of these, 91 (7%) were minor—most commonly nausea, musculoskeletal pain, and pruritus—and 24 (2%) were major, mainly hypotension (1.3%), anaphylaxis (0.2%), and convulsions (0.2%). One patient required ICU transfer after cardiac arrest due to severe hypotension without anaphylaxis. Adverse reaction rates were similar across formulations: ferric derisomaltose (9.1%), ferric gluconate (7.5%), and iron sucrose (7.0%) (p = 0.6008). Most reactions (68%) occurred during infusion; 26% appeared within 1–6 hours after. Management included permanent discontinuation (2%), antihistamines (2%), and rarely epinephrine (0.3%). Documented allergy to intravenous iron was identified as an independent predictor of adverse reactions (OR 3.5; 95% CI 1.7–7.2; p = 0.0006). Female sex, gastroenterology, and obstetrics-gynecology patients showed a non-significant trend toward higher risk. Notably, 83% of patients with major reactions had concurrent hemorrhage, hypoxemic respiratory failure, or active infection, suggesting that underlying comorbidities may increase susceptibility to severe adverse events.
Conclusion: Adverse reactions to intravenous iron were infrequent and mostly mild, with no significant difference between the three iron formulations. A history of iron allergy was the strongest predictor of risk. The high prevalence of comorbidities among patients with major reactions highlights the importance of increased vigilance and, when appropriate, postponing administration until acute conditions are stabilized.
