Reactions to rituximab occur frequently, with up to 77% of patients developing a reaction during initial exposure. The safety of rechallenging patients after a reaction is not clear and standard guidelines are lacking.

To better understand clinical decision making surrounding rituximab reactions and subsequent rechallenge.

We performed a 5-year retrospective review of all rituximab reactions at a large academic outpatient infusion center. Patients' demographic characteristics, clinical symptoms, and management of reactions were reviewed. Reaction severity was classified using standard criteria.

Between June 2006 and January 2011, 67 patients (mean age, 58 ± 13 years, 54% men) with at least 1 rituximab reaction were identified. Most reactions occurred during the first exposure to rituximab (63%). Most reactions (n = 59 [88%]) were grade 1 or 2. Fifty-one patients (n = 51 [88%]) were rechallenged with rituximab on the same day as the initial reaction. Most patients with a grade 1 reaction tolerated rechallenge. Conversely, all 4 patients with a grade 3 reaction had a reaction during rechallenge. The outcome of same-day rechallenge after an initial grade 2 reaction was varied; most patients (26 of 31 [84%]) tolerated same-day challenge, but 5 patients had a reaction (all grade 1-2 severity).

Consistent with previous data, our observations suggest that patients who experience grade 1 reactions to rituximab can be safely rechallenged the same day. A grade 3 or 4 reaction should prompt referral to an allergy specialist for risk assessment before additional rituximab administration. Further research is needed to understand the optimal management of patients with grade 2 reactions.