D2.343 - Anaphylactic Reaction to Methylprednisolone Acetate in a Young Adult

Corticosteroids, including methylprednisolone, are utilized in a broad range of clinical conditions due to their immunosuppressive and anti-inflammatory properties. Despite their frequent use in the treatment of allergic and inflammatory disorders, immediate hypersensitivity reactions to corticosteroids are rare. Reported reactions range from mild cutaneous manifestations to severe, life-threatening anaphylaxis. Both the corticosteroid molecule and its ester derivatives or excipients have been implicated as potential triggers. We report a case of immediate anaphylaxis triggered by methylprednisolone acetate.

A 24-year-old male with no prior medical history was referred to the Allergy department as he experienced an allergic reaction following subcutaneous injections of methylprednisolone acetate for severe burns on his right arm. Symptoms included local pain, dizziness, tachycardia, dyspnea, hoarseness, lip angioedema, and generalized pruritus. Immediate management consisted of intravenous antihistamines and fluid resuscitation, with resolution of symptoms within a few hours.

Skin prick and intradermal tests were performed for hydrocortisone succinate, methylprednisolone succinate, methylprednisolone acetate, and dexamethasone phosphate. A positive reaction was observed exclusively to methylprednisolone acetate, whereas all other corticosteroids tested negative. A graded drug challenge with methylprednisolone by the oral route was successfully completed without adverse effects. Further evaluation with basophil activation testing was declined by the patient.

The findings indicate that the anaphylactic reaction was likely caused by the acetate ester component of methylprednisolone acetate rather than the corticosteroid molecule itself. Clinicians should be aware of ester-specific corticosteroid hypersensitivity when managing patients requiring steroid therapy.