Upadacitinib is an oral Janus kinase inhibitor that has been approved for the treatment of rheumatoid arthritis (RA) at a dose of 15 mg once daily in the European Union and United States, and at doses of 7.5 and 15 mg once daily in Japan.

Compared with the global RA clinical trial population, a higher incidence of serious infections, opportunistic infections, herpes zoster, and creatine phosphokinase elevations was observed in the Japanese population; this increased risk of herpes zoster should be considered when assessing the benefit–risk of prescribing upadacitinib.

In the Japanese population, the safety profiles of upadacitinib 15 mg and 7.5 mg doses were generally similar, except for numerically lower rates of opportunistic infections, herpes zoster, and creatine phosphokinase elevations with the 7.5 mg dose compared with the 15 mg dose, although no statistical comparisons were conducted.