Is Xeljanz an immunosuppressant?
Yes, Xeljanz (tofacitinib) is an immunosuppressant. It reduces the activity of your immune system, which can make it harder for your body to fight infections. Xeljanz also carries an FDA boxed warning — the agency's strongest safety warning — for serious infections, increased risk of death, cancer, major heart-related events, and blood clots. Because of these risks, Xeljanz is generally only prescribed after other treatments, like TNF blockers, haven't worked or couldn't be tolerated.
Why is Xeljanz an Immunosuppressant?
The active ingredient in Xeljanz is tofacitinib, classified as a Janus kinase (JAK) inhibitor. It works by blocking JAK enzymes inside your cells, which helps control inflammation, swelling, and pain, and can reduce or prevent joint damage. Because this same pathway is also part of how your immune system normally functions, blocking it reduces your body's ability to fight off infections.
What is Xeljanz's Boxed Warning?
Xeljanz carries an FDA boxed warning for serious infections, mortality, malignancy, major adverse cardiovascular events (MACE), and thrombosis (blood clots).
Increased Risk of Infections
Some people taking Xeljanz may develop a serious or even deadly infection, including tuberculosis (TB), or infections caused by bacteria, a fungus, or a virus like shingles. These infections can spread throughout the body and may require hospitalization. Many people who developed serious infections in clinical trials were also taking other immune-suppressing medicines, such as methotrexate or corticosteroids.
Increased Risk of Death, Cancer, Heart Problems, and Blood Clots
The trial's final results showed an increased risk of blood clots and death, even at the lower approved dose of Xeljanz, not just the higher dose. The boxed warning also covers an increased risk of certain cancers (malignancies) and major cardiovascular events like heart attack or stroke.
Doctors are advised to consider these risks carefully when deciding whether to start or continue Xeljanz, particularly in current or past smokers and people with other cardiovascular risk factors or a history of cancer.
Do not stop taking Xeljanz on your own if you have concerns about these risks. Stopping suddenly can cause your underlying condition to worsen. Talk to your doctor about your personal risk factors and whether Xeljanz remains the right choice for you.
What Should You Tell Your Doctor Before Starting Xeljanz?
Because of the infection and immunosuppression risks, tell your healthcare provider if you:
- Are currently being treated for an infection, or have a history of frequent infections
- Have tuberculosis (TB), have had TB in the past, or have been in close contact with someone who has TB
- Have diabetes, a chronic lung disease, HIV, or any condition that weakens your immune system
- Are taking any other medications that suppress the immune system, including methotrexate or corticosteroids
- Smoke or have a history of smoking
- Have a history of blood clots, heart attack, stroke, or cancer
Your doctor may test you for TB and other infections before starting Xeljanz, and may continue monitoring you during treatment.
Related questions
- What are JAK inhibitors and how do they work?
- What are the new drugs for rheumatoid arthritis (RA)?
- Which JAK inhibitors are approved in the U.S?
What Are the Signs of an Infection to Watch For?
Call your doctor right away if you notice:
- Fever, sweating, or chills
- A sore that won't heal
- Sore throat
- Red, warm, or painful skin or sores
- Muscle aches
- Changes in phlegm color, or blood in phlegm
- Pain or burning when you urinate, or urinating more often than usual
- A cough or shortness of breath
- Sores in your mouth
- Diarrhea or stomach pain
- Unexplained weight loss
Can You Get Vaccines While Taking Xeljanz?
Because Xeljanz suppresses your immune system, live vaccines are generally not recommended while taking it, since they could cause infection or may not work as well. Non-live vaccines (like the flu shot or most COVID-19 vaccines) are generally considered appropriate, but always confirm timing with your doctor. If possible, your doctor may recommend completing any needed vaccinations, including those for shingles, before starting Xeljanz.
Why is Xeljanz Prescribed?
Xeljanz (tofacitinib) is approved by the FDA to treat rheumatoid arthritis, psoriatic arthritis, ulcerative colitis, ankylosing spondylitis and polyarticular juvenile idiopathic arthritis. It is available as an oral tablet, oral solution, and as an extended-release tablet known as Xeljanz XR.
The active ingredient in Xeljanz is tofacitinib, an immunosuppressant medicine. It is classified as a Janus kinase (JAK) inhibitor and blocks JAK enzymes in the cell. Blocking JAK helps to control inflammation (swelling, pain) and reduce or prevent joint damage.
Do not stop taking Xeljanz without first speaking with your healthcare provider. Stopping your treatment may worsen your condition.
Further information: Xeljanz Uses, Safety and Side Effects (in more detail)
This is not all the information you need to know about Xeljanz (tofacitinib) for safe and effective use and does not take the place of talking to your doctor about your treatment. Review the full Xeljanz information here, and discuss this information and any questions you have with your doctor or other health care provider.
References
- Xeljanz, Xeljanz XR (tofacitinib) prescribing information. Updated March 2026. Accessed on June 20, 2026 at https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=68e3d6b2-7838-4d2d-a417-09d919b43e13&audience=consumer
- Patient education: Rheumatoid arthritis treatment (Beyond the Basics). Up to Date. 7/2021. Accessed August 11, 2021 at https://www.uptodate.com/contents/rheumatoid-arthritis-treatment-beyond-the-basics
Read next
What happens when you stop taking Xeljanz?
Stopping treatment with Xeljanz may cause the symptoms of your condition to return. However, some patients are able to stop Xeljanz without their symptoms flaring up, according to the results of research conducted in patients with rheumatoid arthritis. You should not stop taking Xeljanz without consulting your doctor. Continue reading
How long does Xeljanz take to work?
Xeljanz can work in as little as three days for patients with ulcerative colitis. Some patients with rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis and ankylosing spondylitis will notice an improvement in their symptoms within two weeks, but others may have to wait up to three to four months for Xeljanz to work.
Xeljanz (tofacitinib citrate) is a Janus kinase (JAK) inhibitor and disease modifying anti-rheumatic drug (DMARD), which works by suppressing the immune system. Continue reading
What is Xeljanz used for and is it a biologic?
No, Xeljanz (tofacitinib) is not a biologic. It is an oral small molecule medicine called a Janus kinase (JAK) inhibitor, made through traditional chemical manufacturing rather than from living cells. Xeljanz is used to treat several autoimmune conditions, including moderate to severe rheumatoid arthritis, psoriatic arthritis, ulcerative colitis, ankylosing spondylitis, and polyarticular juvenile idiopathic arthritis. Continue reading
See also:
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