Participants must be adults ages 18-75, have chronic spontaneous urticaria for more than 6 months while using at least one over the counter antihistamine daily (Zyrtec, Allegra or Claritin). This is a double-blind study of an injectable medication given every 4 weeks with 2 different doses vs placebo for 24 weeks. After 24 weeks, all subjects get active medicine. All participants paid for visits with compensation available for travel.