Anaphylaxis Following Intravenous Methylprednisolone Sodium Succinate: A Case Report

Immediate hypersensitivity to systemic corticosteroids is rare but potentially life-threatening, and it may be overlooked when the cardiovascular presentation is atypical. Identifying the responsible determinant, whether the corticosteroid molecule, a solubilizing ester, or a formulation excipient, is often difficult.

A 45-year-old woman with rheumatoid arthritis developed a generalized pruritic, erythematous, raised eruption, dyspnea, hypoxemia, bradycardia, and reduced consciousness within 5 minutes of starting intravenous methylprednisolone sodium succinate 250 mg. The infusion was stopped, and symptoms resolved after intramuscular epinephrine 0.4 mg. Approximately 7 hours later, because the reaction was considered unlikely to be allergic, the same formulation was re-administered in two graded steps (25%, then 75%) under continuous monitoring and direct physician supervision. This high-risk re-exposure after clinically convincing anaphylaxis reproduced the cutaneous and respiratory features, again with bradycardia (heart rate 51 beats/min) and hypoxemia (oxygen saturation 88%), and required intramuscular epinephrine 0.3 mg, an intravenous antihistamine, oxygen, and a bronchodilator. Serum tryptase and formal allergy testing were not obtained. She later reported tolerating oral prednisolone, with no recurrent symptoms during 3 months of follow-up.

Recurrence on re-exposure supports anaphylaxis to the administered methylprednisolone formulation, but without confirmatory testing the reaction cannot be attributed to methylprednisolone itself, the succinate ester, or an excipient. This patient-safety case shows that bradycardia does not exclude anaphylaxis; that a graded challenge is a diagnostic test, not desensitization, and is not a recommended strategy after convincing anaphylaxis; and that the exact implicated formulation should be documented instead of a nonspecific steroid-allergy label.