Arthritis Rheumatol. 2014 Jun 18. [Epub ahead of print]It is well established that patients with RA are at an increased risk of herpes zoster (HZ). What is less well known is whether some of the newer therapies available for treatment of RA increase this risk. Tofacitinib has been reported to be associated with an increased risk of HZ and this study quantifies that risk and reviews potential factors that represent an increased risk. Using data from the tofacitinib RA development programme; phase 2, 3, and long-term extension clinical trials, over 200 cases of HZ associated with tofacitinib were identified from 4789 participants. None of these were complicated HZ. After evaluation, the results showed that increased HZ rates were observed with tofacitinib compared with placebo, and being recruited in Asia represented an increased risk. The authors conclude that preventative strategies need to be developed for HZ regardless of treatment being planned.