Horizon Therapeutics plc is a biopharmaceutical company focused on researching, developing, and commercializing medicines that address critical needs for people impacted by rare and rheumatic diseases. Horizon primarily markets products in the United States, which represented 97% of Horizon's 2019 worldwide sales. In 2014 Horizon executed a tax inversion to move its legal headquarters to Ireland to avail of Ireland's low tax rates and beneficial corporate tax system. On May 2, 2019, shareholders of the company approved the change of the company's name to Horizon Therapeutics plc.
Horizon's drug portfolio is focused on treatments for thyroid eye disease, gout, rare diseases, and inflammatory diseases. Horizon's portfolio includes Tepezza, Krystexxa, Actimmune, Duexis, Pennsaid, Rayos/Lodotra, Vimovo, Buphenyl, Procysbi, and Ravicti. In 2016, the company became a member of the Pharmaceutical Research and Manufacturers of America.