Safety of i.v. administration of redback spider antivenom

It is unclear what the risk of allergic reactions is with appropriately given dilute i.v. redback spider antivenom (RBSAV). Ninety-five i.v. administrations of RBSAV referred from January 2001 to November 2006 were reviewed. All patients had local pain, 72% radiating pain, 57% diaphoresis and 39% systemic effects. Four patients (4%) had immediate systemic hypersensitivity reactions: none were severe, one was moderate and three mild. In 32 patients followed up for 2 weeks, three (10%) developed serum sickness. RBSAV given i.v. had a low reaction rate.