Jakafi

Jakafi is used to treat certain types of myelofibrosis, polycythemia vera (PV) in patients who have already tried hydroxyurea, and acute or chronic graft-versus-host disease (GvHD). It is an oral tablet taken once (Jakafi XR) or twice (Jakafi) a day.

Jakafi works by blocking Janus kinase proteins JAK1 and JAK2, which control signals involved in blood cell production and immune function. In blood cancers such as myelofibrosis and polycythemia vera, blocking these signals reduces abnormal cell growth. In graft-versus-host disease, it suppresses the inflammatory cytokines responsible for tissue damage. Jakafi belongs to the drug class known as kinase inhibitors.

No generic version of Jakafi is currently available. Jakafi (ruxolitinib) received FDA approval on November 16, 2011. Jakafi XR was approved on May 6, 2026.

Jakafi and Jakafi XR are FDA-approved to treat:

• Intermediate or high-risk myelofibrosis (MF), including primary MF, post-polycythemia vera MF, and post-essential thrombocytopenia MF in adults
• Polycythemia vera (PV) in adults who have had an inadequate response to, or are intolerant of, hydroxyurea
• Steroid-refractory acute graft-versus-host disease (aGVHD) in adults and children 12 years and older
• Chronic graft-versus-host disease (cGVHD) after failure of one or two lines of systemic therapy in adults and children 12 years and older.

It is not known if Jakafi or Jakafi XR are safe or effective in children with MF or PV, or in children under 12 with aGVHD or cGVHD.

Take Jakafi exactly as your healthcare provider tells you. Do not change your dose or stop taking Jakafi without first talking to your healthcare provider.

If you are prescribed Jakafi:

• Take it twice a day or exactly as your healthcare provider tells you, with or without food.
• Jakafi may also be given through certain nasogastric tubes. Tell your healthcare provider if you cannot take Jakafi by mouth. Your healthcare provider will decide if you can take Jakafi through a nasogastric tube. Ask your healthcare provider for specific instructions on how to do this.

If you are prescribed Jakafi XR:

• Take it once a day with or without food.
• Swallow Jakafi XR whole. Do not split, chew, or crush.

If you miss a dose of Jakafi or Jakafi XR, take your next dose at your regular time. Do not take 2 doses at thesame time.

Before taking Jakafi or Jakafi XR, tell your healthcare provider about all of your medical conditions, including if you:

• have or have had low white or red blood cell counts
• have an infection
• have or had tuberculosis (TB), or have been in close contact with someone who has TB
• have had shingles (herpes zoster)
• have or had hepatitis B
• have a high level of fat in your blood (high blood cholesterol or triglycerides)
• have had a blood clot, heart attack, other heart problems, or stroke
• are a current or past smoker
• have had cancer in the past
• have or have had kidney problems or are on dialysis. If you are on dialysis, Jakafi should be taken after your dialysis
• have or have had liver problems
• are pregnant or plan to become pregnant. It is not known if Jakafi or Jakafi XR will harm your unborn baby.
• are breastfeeding or plan to breastfeed. It is not known if Jakafi or Jakafi XR passes into your breast milk. Do not breastfeed during treatment with Jakafi or Jakafi XR and for 2 weeks after the final dose.

Common side effects

The most common side effects of Jakafi or Jakafi XR in adults with MF and PV are:

• low platelet counts
• low red blood cell counts
• bruising
• dizziness
• headache
• diarrhea.

The most common side effects of Jakafi or Jakafi XR in people with aGVHD are:

• low red blood cell counts
• low platelet counts
• low white blood cell counts
• infections
• swelling.

The most common side effects of Jakafi or Jakafi XR in people with cGVHD are:

• low red blood cell counts
• low platelet counts
• infections, including viral infections.

Serious side effects and warnings

Jakafi can cause the following serious side effects:

• Low blood cell counts. Jakafi or Jakafi XR may cause low platelet counts (thrombocytopenia), low red blood cell counts (anemia), and low white blood cell counts (neutropenia). If you develop bleeding, stop the medicine and call your healthcare provider. Your healthcare provider will do a blood test to check your blood cell counts before you start Jakafi or Jakafi XR and regularly during your treatment. Tell your healthcare provider right away if you develop or have worsening of any of these symptoms: unusual bleeding bruising tiredness shortness of breath fever.
• Infection. Jakafi or Jakafi XR can weaken your immune system, making you more vulnerable to serious infections, including bacterial, fungal, and viral infections. Contact your doctor immediately if you develop a fever, chills, nausea, vomiting, or any signs of infection. Specific infections to be aware of: Tuberculosis (TB): Your doctor will screen you for TB before starting treatment, especially if you have travelled to high-risk countries or been in contact with someone with TB Shingles and cold sores: Tell your doctor immediately if you develop a rash or blistering Hepatitis B: If you have a history of Hepatitis B, your doctor will monitor you closely as Jakafi may cause the virus to become active again PML (a rare but serious brain infection): If you experience any unusual neurological symptoms such as confusion, weakness, or vision changes, seek urgent medical attention

Before starting Jakafi or Jakafi XR, tell your doctor about any past or current infections, travel history, or previous TB exposure. Do not start this medicine if you have an active serious infection. Tell your healthcare provider immediately if you develop any of the following symptoms of infection.

• Worsening of symptoms after stopping treatment. Signs and symptoms of myelofibrosis may worsen after you stop treatment with Jakafi or Jakafi XR. Do not interrupt or stop treatment without talking to your healthcare provider. Tell your healthcare provider right away if you get fever, trouble breathing, feeling dizzy or lightheaded, weakness, night sweats, or pain in your left upper stomach area or left shoulder after stopping treatment.

• Cancer. Some people have had certain types of non-melanoma skin cancers during treatment with Jakafi or Jakafi XR. Your healthcare provider will regularly check your skin during your treatment with Jakafi. Tell your healthcare provider if you develop any new or changing skin lesions during treatment with Jakafi.
• Cholesterol increases. You may have changes in your blood cholesterol levels during treatment with Jakafi or Jakafi XR. Your healthcare provider will do blood tests to check your cholesterol levels about every 8 to 12 weeks after you start taking Jakafi or Jakafi XR, and as needed.
• Increased risk of major cardiovascular events, such as heart attack, stroke, or death, in people who have cardiovascular risk factors and who are current or past smokers while using another JAK inhibitor to treat rheumatoid arthritis. Get emergency help right away if you have any symptoms of a heart attack or stroke while taking Jakafi, including: discomfort in the center of your chest that lasts for more than a few minutes, or that goes away and comes back severe tightness, pain, pressure, or heaviness in your chest, throat, neck, or jaw pain or discomfort in your arms, back, neck, jaw, or stomach shortness of breath with or without chest discomfort breaking out in a cold sweat nausea or vomiting feeling lightheaded weakness in one part or on one side of your body slurred speech.
• Increased risk of blood clots. Blood clots in the veins of your legs (deep vein thrombosis, DVT) or lungs (pulmonary embolism, PE) have happened in people taking another JAK inhibitor for rheumatoid arthritis and may be life-threatening. Tell your healthcare provider right away if you have any signs and symptoms of blood clots during treatment with Jakafi or Jakafi XR, including: swelling, pain, or tenderness in one or both legs sudden, unexplained chest or upper back pain shortness of breath or difficulty breathing.
• Possible increased risk of new (secondary) cancers. People who take another JAK inhibitor for rheumatoid arthritis have an increased risk of new (secondary) cancers, including lymphoma and other cancers. People who smoke or who have smoked in the past have an added risk of new cancers.

These are not all the possible side effects of Jakafi or Jakafi XR. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects to Incyte Corporation at 1-855-463-3463.

Dose of Jakafi or Jakafi XR for Myelofibrosis

Dosage is based on the patient’s baseline platelet count:

• Greater than 200 x 109/L: Jakafi 20 mg orally twice daily or Jakafi XR 44 mg orally once daily
• 100 x 109/L to 200 x 109/L: Jakafi 15 mg orally twice daily or Jakafi XR 33 mg orally once daily
• 50 x 109/L to less than 100 x 109/L: Jakafi 5 mg orally twice daily or Jakafi XR 11 mg orally once daily.

Dose of Jakafi or Jakafi XR for Polycythemia Vera

• Initial: Jakafi 10 mg orally twice daily or Jakafi XR 22 mg orally once daily.

Dose of Jakafi or Jakafi XR for Acute Graft-Versus-Host-Disease (aGVHD)

• Initial: Jakafi 5 mg orally twice daily or Jakafi XR 11 mg orally once daily.

Dose of Jakafi or Jakafi XR for Chronic Graft-Versus-Host Disease (cGVHD)

• Initial: Jakafi 10 mg orally twice daily or Jakafi XR 22 mg orally once daily.

If you miss a dose of Jakafi, take your next dose at your regular time. Do not take 2 doses at the same time.

If you take too much Jakafi, call your healthcare provider or go to the nearest hospital emergency room right away.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Taking Jakafi with certain other medicines may affect how Jakafi works. Especially tell your healthcare provider if you take:

• Fluconazole (an antifungal medicine). If you are taking fluconazole at doses greater than 200mg, you should not take Jakafi at the same time. If you are taking a lower dose of fluconazole (200mg or less), your doctor will reduce your Jakafi dose to keep you safe.
• Strong antifungal or antibiotic medicines that affect how your liver processes drugs (known as strong CYP3A4 inhibitors, such as ketoconazole, clarithromycin, or ritonavir). These may require your doctor to reduce, pause, or stop your Jakafi dose.
• Certain medicines that affect how your liver processes drugs (known as strong CYP3A4 inducers). These medicines may decrease the amount of Jakafi in your blood and make it less effective. Your doctor may need to monitor you closely and adjust your Jakafi dose.

Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

Store Jakafi or Jakafi XR at room temperature 68°F to 77°F (20°C to 25°C). Tightly close the bottle after you take your dose and keep it tightly closed to protect from light.

Keep out of the reach of children.

Active ingredient: ruxolitinib phosphate

Inactive ingredients (Jakafi): microcrystalline cellulose, lactose monohydrate, magnesium stearate, colloidal silicon dioxide, sodium starch glycolate, povidone, and hydroxypropyl cellulose.

Inactive ingredients (Jakafi XR): colloidal silicon dioxide, hypromellose, lactose monohydrate, magnesiumstearate, microcrystalline cellulose, and sodium stearyl fumarate. In addition, the film coating contains the following inactive ingredients: colorants (black iron oxide, red iron oxide, and yellow iron oxide), copovidone, hypromellose, polydextrose, polyethylene glycol, titanium dioxide, and triglycerides.

Jakafi is available as 5 mg, 10 mg, 15 mg, 20 mg, and 25 mg tablets.

Jakafi XR tablets are available as 11 mg, 22 mg, 33 mg, 44 mg, or 55 mg of ruxolitinib free base equivalent to 14.5 mg, 29 mg, 43.6 mg, 58.1 mg, or 72.6 mg of ruxolitinib phosphate, respectively.

Jakafi is made by Incyte Corporation, located in Wilmington, DE 19803.