Janus Kinase (JAK) Inhibitors

Janus kinase (JAK) inhibitors are a new class of drugs used to treat moderate to severe atopic dermatitis (the most common form of eczema). These drugs may be used topically (on the skin) or taken orally (by mouth).1-3

Before 2021, JAK inhibitors were only used to treat some chronic inflammatory conditions, such as rheumatoid arthritis and ulcerative colitis.1-3

How do JAK inhibitors work?

Cytokines are immune system messengers that cause inflammation. People with atopic dermatitis have higher levels of cytokines. Some cytokines use pathways called the Janus Kinase-Signal transducer and activators of transcription (JAK-STAT). Cytokines use these pathways to drive abnormal immune responses in conditions like atopic dermatitis.2,3

JAK inhibitor drugs block overactive JAK pathways. This lowers the cytokines that turn on atopic dermatitis symptoms like redness, itching, and inflammation.2,3

JAK inhibitors for atopic dermatitis

In September 2021, OpzeluraTM (ruxolitinib) cream became the first topical JAK inhibitor approved to treat atopic dermatitis.1

Other JAK inhibitors for atopic dermatitis are being studied in clinical trials. Unlike Opzelura, these potential JAK inhibitors will be taken by mouth:1-3

  • Abrocitinib
  • Baricitinib
  • Upadacitinib

Other JAK inhibitors are expected to be developed in the next several years, as the JAK pathway is major area of drug study.2,3

What are the possible side effects?

Side effects can vary depending on the specific drug you are taking. Generally, common side effects of JAK inhibitors include:1-4

  • Nausea
  • Swelling of the nasal passages and back of the throat
  • Diarrhea
  • Headache
  • Upper respiratory infections

Serious side effects

In rare cases, JAK inhibitors may cause serious side effects, including:3,4

  • Serious infections that can cause hospitalization or death, including tuberculosis
  • A higher rate of death, including sudden cardiovascular death
  • Lymphoma and other cancers
  • Major heart effects including heart attack, stroke, and death
  • Clotting events, including clots in the lungs and legs, that can cause death

These are not all the possible side effects of JAK inhibitors. Talk to your doctor about what to expect when taking a JAK inhibitor. You should also call your doctor if you have any changes that concern you when taking a JAK inhibitor.

Things to know about JAK inhibitors

JAK inhibitors work on the immune system. They can lower your body’s ability to fight infections. Your doctor will monitor you for signs of infection during and after treatment with these drugs. Get medical help right away if you have signs of an infection, including fever, muscle pain, cough, shortness of breath, diarrhea, extreme tiredness, or pain while urinating.3,4

There is an increased risk of heart attack, stroke, or death in people with risk factors who smoke or used to smoke while using JAK inhibitors. Seek medical help right away if you have chest pain or tightness, pain in the chest/throat/neck/jaw, shortness of breath, cold sweats, nausea, vomiting, weakness on one side of the body, or slurred speech.3,4

JAK inhibitors can cause blood clots in leg veins. This is called deep vein thrombosis (DVT). These clots can travel to the lungs. This is called pulmonary embolism (PE). DVT or PE can be life-threatening. Get medical help right away if you have pain, swelling, or tenderness in the leg(s), sudden chest or upper back pain, or shortness of breath.3,4

JAK inhibitors can cause low blood cell counts. Your doctor will order lab tests during treatment. Tell your doctor if you have unusual bruising or bleeding, shortness of breath, fever, or tiredness.3,4

Before beginning treatment for atopic dermatitis, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

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Written by: Karen Berger and Heather Morse | Last reviewed: October 2021