Multisystem inflammatory syndrome in adults, MIS-A, is a rare but severe post-covid-19 immunologic complication. The presentation is similar to Multisystem inflammatory syndrome in children, MIS-C. Both MIS-A/C are life-threatening immunologic syndromes characterized by hypotension, skin rashes, myocardial affection, coagulopathy and GI symptoms. Here we describe a case of MIS-A in a 35-year-old previously healthy female who, five weeks after a mild covid-19 infection, presented with a life-threatening immunological reaction. The patient made a swift recovery upon treatment with immunoglobulins, corticosteroids and an interleukin-1 receptor antagonist. We want to highlight the importance of immunological derangements following covid-19 infections in adults. We also present a treatment suggestion for MIS-A based on the management routine for MIS-C, which has been developed from international discussions and collaborations by pediatric rheumatologists in Sweden and around the world.