JAK Inhibitors

Inflammatory bowel disease, or IBD, can include several conditions that involve chronic inflammation of the digestive tract. Chronic inflammation can cause significant damage to the gastrointestinal (GI) tract and cause symptoms like cramping or diarrhea. There is no cure, but IBD can be treated and symptoms can be addressed. One of these treatments is a class of medications called JAK inhibitors.1

What are JAK inhibitors?

Janus kinase (JAK)/signal transducers and activators of the transcription (STAT) pathway are linked to various cytokines and are involved in a variety of immune-mediated and inflammatory diseases.1 JAK inhibitors are drugs that are broken down in the GI tract and then carried through the bloodstream to block inflammation reactions and pathways.2 This helps to mediate intestinal inflammation involved in IBD.

What types of JAK inhibitors are used to treat people with inflammatory bowel disease?

Xeljanz (generic name tofacitinib) is a JAK inhibitor that is FDA-approved for adults with moderately to severe ulcerative colitis (UC). It is the only JAK inhibitor approved for IBD as of November 2019. JAK inhibitors are also being studied for use in Crohn’s disease.2 These drugs have been used for other immune-related diseases like rheumatoid arthritis for many years, but are only recently being used for IBD.

How are JAK inhibitors taken?

Xeljanz is an oral medication. The tablets should not be crushed, chewed, or split in half.3 Your doctor will provide you with any other information that is needed.

Even after your symptoms lessen, keep taking the JAK inhibitor. This will continue to control your symptoms and keep them at bay, and reduce the risk of future flare-ups.

What are the side effects or risks of JAK inhibitors?

Any medication can cause side effects and carry various risks. Not every person taking the medication will experience side effects, and many times, the side effects resolve on their own after a period of time. Prior to taking a JAK inhibitor for IBD, the doctor should discuss with you all of the potential side effects, as well as any risks, as well as the potential benefits for your IBD.

Common side effects of Xeljanz can include:3

  • Nasal congestion and runny nose
  • Increased cholesterol levels
  • Headache
  • Rash
  • Diarrhea
  • Shingles
  • Upper respiratory tract infections

These are not all the possible side effects of JAK inhibitors. Patients should talk to their doctor about what to expect with treatment with JAK inhibitors.

If you are a carrier of Hepatitis B or C, the virus may become activated while on Xeljanz.3 Bloodwork may need to be done prior to starting treatment with a JAK inhibitor as well as while you take Xeljanz. Tell your doctor if you are taking the JAK inhibitor and experience symptoms like extreme fatigue, loss of appetite, chills or muscle aches, clay-colored stools, or have a skin rash.3

If you notice any symptoms that don’t go away or experience side effects that are especially bothersome, talk with your doctor about it. Tell your doctor about any other medications you are taking, as well as any supplements, over-the-counter medications, or vitamins that you take.

Women who are pregnant, plan to become pregnant, or who are breastfeeding should talk with the doctor before taking a JAK inhibitor like Xeljanz. There is not enough information right now about the possible risks to a fetus or newborn.

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Last reviewed: November 2021.