Risankizumab-rzaa (RZA) is a fully human immunoglobulin G monoclonal antibody (Mab) which has fewer immunogenic concerns compared with chimeric Mabs. The pivotal trials of RZA found no significant differences in infusion reactions between drug and placebo. This case illustrates successful transition to subcutaneous RZA following a serious hypersensitivity reaction to intravenous RZA.