 In December of 2017 the U.S. Food and Drug Administration expanded mepolizumab's use to treat adult patients with eosinophilic granulomatosis with polyangiitis (EGPA), which is a rare autoimmune condition that can cause vasculitis.Common side effects in clinical trials included headache (19% of patients under mepolizumab treatment versus 18% under placebo), reactions at the site of injection (8% versus 3%), infections of the urinary tract (3% versus 2%) and the lower respiratory tract, eczema and muscle spasms (both 3% versus <1%).Single doses of 15 times the usual therapeutic dose have been tolerated in studies without significant side effects.