Tofacitinib: what it treats, how to take it, side effects
Last updated September 3, 2026.
Tofacitinib (brand name Xeljanz) is a JAK inhibitor, a targeted pill that turns down the immune signaling behind several autoimmune diseases. It treats rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and ulcerative colitis, and it carries a boxed warning covering serious infections, blood clots, cancer, and cardiovascular events.
What does it treat?
It is used when at least one TNF blocker has failed or was not tolerated: moderate to severe rheumatoid arthritis, active psoriatic arthritis, ankylosing spondylitis, and moderate to severe ulcerative colitis. A lower-strength form treats some juvenile arthritis. It calms the immune attack on joints and gut; it does not cure the underlying disease, so stopping usually means symptoms return.
How do you take it?
For RA, PsA, or AS: 5 mg twice daily, or the extended-release 11 mg once daily. UC starts higher and steps down. Take it at the same times daily, with or without food, and swallow the XR tablet whole. Before starting, you get screened for tuberculosis and hepatitis, and vaccination should be current, with live vaccines avoided during treatment. If a serious infection develops, the drug is paused until it is controlled. Missed dose: take it when remembered unless the next dose is near; never double up.
Side effects to know
- Common: upper respiratory infections, headache, diarrhea, nausea, and raised cholesterol.
- Serious: the boxed-warning list: serious infections including TB reactivation, blood clots in legs or lungs, higher rates of lymphoma and other cancers, major cardiovascular events like heart attack and stroke (seen in patients 50+ with at least one cardiovascular risk factor), and gut perforation. Shingles is common enough to make the shingles vaccine worth discussing before starting.
Who should not take it?
Avoid it with active serious infection, and weigh it carefully with a history of blood clots, cancer, heart disease, or smoking, and in anyone over 65, since the safety signal concentrates there. It is not combined with other biologics or strong immunosuppressants. Live vaccines are out during treatment. Pregnancy and breastfeeding are generally avoided; discuss plans with your rheumatologist well ahead.
When is it an emergency?
Call 911 for possible clot signs (sudden shortness of breath, chest pain, one-sided leg swelling), stroke or heart-attack symptoms, or a severe allergic reaction. High fever with confusion, or severe abdominal pain with fever, also means emergency care. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
What does the boxed warning actually mean for me?
It flags five observed risks: serious infections, death, cancer, major cardiovascular events, and blood clots. The cardiovascular and clot signals were strongest in patients 50 and older with at least one cardiovascular risk factor. Your rheumatologist weighs these against uncontrolled disease, which carries its own cardiovascular risk, using your age, smoking, clot history, and cancer history.
Is tofacitinib a biologic?
No, and the distinction is practical. It is a small-molecule targeted drug (a JAK inhibitor), taken as a pill rather than an injection or infusion. It is not combined with biologics, because stacking biologic-level immunosuppression multiplies infection risk without adding benefit.
Why do I need a TB test before starting?
Tofacitinib can wake up latent tuberculosis, an infection sitting silent in the lungs for years. The label requires screening before and during treatment, and latent TB gets treated before the drug starts. A skin or blood test you had years ago does not count; it gets repeated.
Should I get the shingles vaccine first?
Worth discussing, yes. Shingles rates run higher on JAK inhibitors, and the recombinant (non-live) shingles vaccine is compatible with treatment. Ideally vaccination happens before starting, but it can be given during therapy too; your rheumatologist sequences it.
How fast does tofacitinib work for RA?
Faster than most. Some patients feel improvement within 2 weeks, with the fuller response building over 3 months. If nothing has moved by then, the drug is not earning its risks for you, and the plan changes.
Can I drink alcohol on tofacitinib?
There is no direct labeled interaction, but both alcohol and this drug ask work of the liver, and heavy drinking plus immunosuppression is a bad combination for infection risk. Moderate intake with your doctor's awareness is the usual frame.