* Tofacitinib (Xeljanz) has been approved to treat moderate-to-severe rheumatoid arthritis in adults who've had an inadequate response to or cannot tolerate methotrexate.
* The drug can produce serious, even life-threatening, infections. The most common serious infections reported include pneumonia, cellulitis, herpes zoster, and urinary tract infection. Tuberculosis and other opportunistic infections are also possible.
* Tofacitinib can decrease various cell counts, and blood counts need to be assessed carefully before and during therapy.