Multiple myeloma (MM) is a clonal proliferation of malignant bone marrow plasma cells with high and uniform expression of CD38 [1]. Survival has improved with autologous stem cell transplantation, proteasome inhibitors (bortezomib and carfilzomib), and immunomodulatory drugs (lenalidomide, thalidomide, and pomalidomide). Nevertheless, most patients die of refractory disease despite the use of the abovementioned first-line therapies. Humanized monoclonal antibodies represent a significant addition or even the only therapeutic option for the treatment of refractory MM. Daratumumab is a novel IgG1κ human monoclonal antibody that binds to CD38 and induces apoptosis [1]. Around 38.8% of patients treated with daratumumab develop infusion-related reactions (IRRs) after the first or second dose. They usually present with grade 1 or 2 IRRs, which manifest as rhinitis, cough, dyspnea, bronchospasm, chills, and nausea. Grade 3-4 IRRs are rare (3.8%)[1].

A 66-year-old woman with a history of refractory MM started treatment with daratumumab (final dose, 896 mg) owing to disease progression. This included intravenous premedication with 5 mg dexchlorpheniramine, 1000 mg paracetamol, and 20 mg dexamethasone administered 60 minutes prior to the infusion. Within 30 minutes of initiating daratumumab, the patient developed flushing, oropharyngeal pruritus, bronchospasm, and poor respiratory mechanics. The vital signs were as follows: oxygen saturation, 85%; blood pressure, 80/40 mmHg; pulse, 60 bpm; and temperature, 36.5 ºC. The infusion was stopped, and intravenous methylprednisolone (60 mg), hydrocortisone (200 mg),