Summary:A Japanese female patient with angioimmunoblastic T cell lymphoma underwent allogeneic bone marrow transplantation (BMT) from her brother. Cyclosporine at a dose of 3 mg/kg was started by continuous infusion over 24 h on day −1 of BMT. Within a couple of minutes after the infusion was begun, she developed diffuse pruritic erythema on her whole body and tachycardia. The infusion was immediately stopped and corticosteroid was given, resulting in disappearance of the erythema gradually. She was then switched to intravenous tacrolimus. However, she suffered urticalial erythema again. Since polyoxyethylated castor oil, a solubilizer used in the injective formulation of both cyclosporine and tacrolimus, is considered to be responsible for the reaction, she was given oral capsules of cyclosporine (Sandimmun) in which polyoxyethylated castor oil was not contained. No further anaphylactic reaction was observed. The BM cells were successfully engrafted without causing severe GVHD. She was discharged on cyclosporine capsules without any further adverse effects. Anaphylaxis to intravenous cyclosporine and tacrolimus is a very rare but a serious complication. Our present case indicates that oral capsule of Sandimmun is a safe alternative to prevent GVHD in such a case of anaphylactic reaction against intravenous formulation. Bone Marrow Transplantation (2001) 28, 421-423. Keywords: anaphylaxis; cyclosporine; tacrolimus Cyclosporine has been widely used to prevent graft-versushost disease (GVHD) in allogeneic bone marrow transplantation (BMT) as well as to allow engraftment of transplanted organs including kidney, liver and heart allografts. ever, once anaphylaxis has occurred in a BMT recipient, another immunosuppressive agent is needed since high-dose chemotherapy with or without total body irradiation has been already given prior to the start of cyclosporine, for GVHD prophylaxis. Tacrolimus is an alternative agent often used for the treatment of GVHD when cyclosporine is not effective. Here, we report a patient who developed anaphylaxis to both intravenous cyclosporine and tacrolimus but who tolerated oral cyclosporine in capsule form.A 45-year-old Japanese woman with angioimmunoblastic T cell lymphoma was admitted for allogeneic BMT from her HLA-identical brother. She had had no history of drug allergy while she received anti-neoplastic chemotherapy for 8 months. Following 2 Gy of total body irradiation once daily for 3 consecutive days (total 6 Gy) and the intravenous administration of cytarabine 1 g/m 2 twice daily for 2 days and cyclophosphamide 50 mg/kg once daily for 2 days, she started cyclosporine 1 day prior to BMT. Cyclosporine at a dose of 3 mg/kg was mixed in 500 ml of 5% glucose solution for continuous 24 h infusion. A couple of minutes after the start of the infusion, she developed diffuse pruritic erythema with wheals on her extremities, trunk and face. Her pulse rate increased to 110/min but the blood pressure and respiratory rate did not alter. The infusion was immediately stopped and corticostero...