Immediate infusion reaction to intravenous ustekinumab in three Crohn's disease patients: a case report and review of the literature.

Recently, ustekinumab has been approved for the treatment of Crohn's disease and ulcerative colitis. Treatment is started with an intravenous induction dose, followed by a subcutaneous dosage. We present three patients with therapy-refractory Crohn's disease, who experienced an immediate infusion reaction to intravenous administration of ustekinumab. In two of these patients a subsequent reaction to subcutaneous injections occurred. Clinical features and pathophysiology are discussed.