Xeljanz (active substance tofacitinib) is a medicine for treating adults with moderate to severe rheumatoid arthritis, a disease that causes inflammation of the joints. Tofacitinib is used together with methotrexate after treatment with one or more medicines known as disease-modifying anti-rheumatic drugs (DMARDs) has not worked well enough or has led to troublesome side effects. It can also be taken alone by patients who cannot take or are intolerant to methotrexate.

Treatment may be stopped in patients who develop infection, which is a known side effect of the medicine, or in those with abnormal blood tests. The dose may also be lowered in some patients with reduced kidney or liver function. Tofacitinib, works by blocking the action of enzymes known as Janus kinases. These enzymes play an important role in the process of inflammation and joint damage that occur in rheumatoid arthritis. By blocking their action, tofacitinib helps reduce the inflammation and other symptoms of the disease. Six studies in over 4,200 patients with rheumatoid arthritis have shown that tofacitinib is effective at reducing joint pain and swelling, improving joint movement and slowing down joint damage. Most patients in these studies had tried other treatments before and most took tofacitinib with methotrexate. In one of the studies, where tofacitinib was taken alone, tofacitinib was more effective than methotrexate at slowing down joint damage and reducing symptoms. In another study, tofacitinib taken alone was more effective than placebo at reducing symptoms, such as pain and swelling. The most common side effects with Xeljanz are headache, infection and inflammation of the nose and throat, diarrhoea, nausea and hypertension. The most common serious side effects seen with tofacitinib are serious infections such as pneumonia, cellulitis, herpes zoster, urinary tract infection, diverticulitis and appendicitis as well as opportunistic infections that can occur in patients with weakened immune systems. Xeljanz must not be used in patients with active tuberculosis, serious infections or any opportunistic infection. Tofacitinib must also not be used in patients with severely reduced liver function or in pregnant and breastfeeding women.