Jakafi (ruxolitinib) is a brand-name oral tablet that’s prescribed for myelofibrosis, graft-versus-host disease (GVHD), and other blood conditions in some adults and children. As with other drugs, Jakafi can cause side effects, such as anemia and a low platelet count.

Jakafi belongs to a drug class called kinase inhibitors. The drug is not available in a generic version.

Read on to learn about potential common, mild, and serious side effects of Jakafi. For a general overview of the drug, including more details about its uses, see this article.

Jakafi can cause certain side effects, some more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Jakafi’s side effects can vary depending on the condition you’re taking the drug to treat. (You can learn more about Jakafi’s uses in this article.) The table below shows the more common side effects reported by people taking Jakafi for the following conditions:

MyelofibrosisPolycythemia veraAcute (sudden) GVHDChronic (long lasting) GVHD
low white blood cell count
bruising
• dizziness
anemia*
low platelet count*
• diarrhea
• dizziness
muscle spasms
shortness of breath
• anemia*
swelling
• internal bleeding
fatigue
• shortness of breath
infections*
muscle pain
fever
• anemia*
• low platelet count*
• infections*

* For more information about this side effect, see the “Side effect specifics” section below.

Mild side effects can occur with Jakafi use. They can vary depending on the condition you’re taking Jakafi to treat. (You can learn more about Jakafi’s uses in this article.) Jakafi’s side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

The information in the table below doesn’t include all possible mild side effects of the drug. For more information, you can refer to Jakafi’s prescribing information.

Mild side effects that people taking Jakafi for the following conditions have reported include:

MyelofibrosisPolycythemia veraAcute (sudden) GVHDChronic (long lasting) GVHD
• weight gain
passing gas
bruising
• dizziness
• headache
urinary tract infection (UTI)
• mild allergic reaction*
• weight gain
• diarrhea
• dizziness
• constipation
muscle spasms
shortness of breath
• UTI
• nausea
• mild allergic reaction*
rash
• diarrhea
fatigue
swelling
• dizziness
• headache
• shortness of breath
• mild allergic reaction*
muscle pain
fever
• diarrhea
• fatigue
• cough
• shortness of breath
• nausea
• mild allergic reaction*

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Jakafi and want to tell the FDA about it, visit MedWatch.

* An allergic reaction is possible after taking Jakafi. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Jakafi may cause serious side effects, which vary depending on the condition you are taking Jakafi to treat. (You can learn more about Jakafi’s uses in this article.) The information in the table below may not include all possible serious side effects of the drug. For more information, you can refer to Jakafi’s prescribing information.

If you develop serious side effects while taking Jakafi, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported in people taking Jakafi for the following conditions include:

MyelofibrosisPolycythemia veraAcute (sudden) GVHDChronic (long lasting) GVHD
Low white blood cell count. Symptoms may include frequent infections as well as fatigue and fever.
Shingles. Symptoms may include a painful, tingling, and itchy rash on one section of your body.
Increased liver enzyme levels.
High cholesterol, which does not usually cause symptoms.
Anemia.*
Low platelet count.*
• Severe allergic reaction.†
• Low white blood cell count. Symptoms may include frequent infections as well as fatigue and fever.
• Shingles. Symptoms may include a painful, tingling, and itchy rash on one section of your body.
• Increased liver enzyme levels.
High blood pressure, which does not usually cause symptoms.
• High cholesterol and triglycerides, which do not usually cause symptoms.
• Anemia.*
• Low platelet count.*
• Severe allergic reaction.†
• Low white blood cell count. Symptoms may include frequent infections as well as fatigue and fever.
• Increased liver enzyme levels.
• High blood pressure, which does not usually cause symptoms.
• High triglycerides, which do not usually cause symptoms.
Internal bleeding. Symptoms can include bruising, dizziness, and low blood pressure.
• Anemia.*
• Low platelet count.*
Infections.*
Blood clots.*
• Severe allergic reaction.†
• Low white blood cell count. Symptoms may include frequent infections as well as fatigue and fever.
• Increased liver enzyme levels.
Increased creatinine levels, which do not usually cause symptoms.
• Increased lipase and amylase levels, which do not usually cause symptoms.
Swelling. Symptoms can include weight gain and puffiness in your abdomen, legs, or ankles.
• High blood pressure, which does not usually cause symptoms.
• High cholesterol, which does not usually cause symptoms.
• Anemia.*
• Low platelet count.*
• Infections.*
• Severe allergic reaction.†

* For more information about this side effect, see the “Side effect specifics” section below.
† An allergic reaction is possible after taking Jakafi. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Jakafi may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Can Jakafi cause long-term side effects?

Jakafi may cause long-term side effects. Drugs similar to Jakafi have caused serious side effects resulting in long-term health problems. These problems include:

If you have concerns about possible long-term side effects from Jakafi, talk with your doctor.

* This is a serious side effect of Jakafi. For more information about this side effect, see the “Side effect specifics” section below.

Does stopping Jakafi cause certain side effects?

It’s not likely you’ll experience side effects from stopping Jakafi. However, some people taking Jakafi in clinical trials for myelofibrosis saw their symptoms return when they stopped taking it. Symptoms for myelofibrosis can include:

Tell your doctor right away if you experience these or other unusual symptoms. If your symptoms seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Due to the risk of symptoms returning, your doctor will lower your Jakafi dosage slowly. As with other drugs, do not change your Jakafi dosage without your doctor’s recommendation. To learn more about Jakafi dosages, see this article.

If you have questions about what to expect during and after Jakafi treatment, talk with your doctor.

Learn more about some of the side effects that Jakafi may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Jakafi.

Anemia

Anemia was one of the most common side effects reported by people taking Jakafi in clinical trials. Anemia is having fewer red blood cells than usual.

Symptoms of anemia can include:

What you can do

If you notice any symptoms of anemia while taking Jakafi, let your doctor know. They’ll likely order a blood test to check for this side effect. In some cases, your doctor may recommend temporarily stopping Jakafi treatment. This may allow time for your body to make new blood cells. Or they may recommend a blood transfusion to get your red blood cell levels back to usual.

Low platelet count

Jakafi may cause a low platelet count. Platelets are a type of blood cell that help blood clot. If you have too few platelets, your blood may not clot as usual. You may experience bleeding symptoms. A low platelet count was a common side effect in Jakafi’s clinical trials.

Symptoms can include:

What you can do

Let your doctor know right away if you notice any of the symptoms listed above. They’ll likely order a blood test to check your platelet count. In some cases, your doctor may recommend a lower dosage of Jakafi. They may also have you stop taking the drug for a while. This may allow time for your body to make more platelets and increase your platelet level. For information about Jakafi dosages, see this article.

If your platelet count is too low, your doctor may recommend a platelet transfusion to increase the platelet levels in your blood.

Infections

In clinical trials of Jakafi, infections were a commonly reported side effect.

Symptoms can include:

Some of these infections were serious. Serious infections reported by people in clinical trials included:

What you can do

Let your doctor know about any new infections you may have. You may need treatment with an antibiotic or other medication to manage the infection. Your doctor may also recommend a lower dosage of Jakafi. For information about Jakafi dosages, see this article. Sometimes, they may have you stop taking the drug until your infection clears up.

Blood clots

Taking Jakafi may cause blood clots, but this was rare in clinical trials. A blood clot is a collection of blood inside a blood vessel, such as a deep vein thrombosis.

Symptoms vary depending on the clot location but can include:

What you can do

If you experience any of the symptoms above, call your doctor right away. However, some blood clots are medical emergencies. So if your symptoms are severe and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Allergic reaction

As with most drugs, Jakafi can cause an allergic reaction in some people. However, this side effects wasn’t reported in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Jakafi. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Jakafi. This drug may not be the right treatment option for you if you have certain medical conditions or other factors affecting your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Tuberculosis. If you’ve had tuberculosis (TB), taking Jakafi increases the chance of the bacteria becoming active again. Due to this risk, your doctor will give you a TB test before you take Jakafi. The test identifies whether you have the TB bacteria in your body. If your test is positive, your doctor will determine whether Jakafi treatment is safe for you. If you develop TB while taking Jakafi, your doctor may pause the drug while they treat the infection.

Hepatitis B. If you have hepatitis B, taking Jakafi can increase the amount of this virus in your body. So let your doctor know if you’ve ever had treatment for hepatitis B. They’ll likely monitor your liver function to reduce the chance of hepatitis B flare-ups. Sometimes, increased liver enzymes may suggest liver damage.

Herpes zoster and herpes simplex. If you’ve had a herpes infection, taking Jakafi may cause the infection to come back. If it does, your doctor may have you stop taking Jakafi while they treat the herpes infection.

Allergic reaction. If you’ve had an allergic reaction to Jakafi or any of its ingredients, your doctor will likely not prescribe Jakafi. Ask your doctor what other medications may be better options for you.

Liver damage. Liver damage may increase your risk of Jakafi side effects. Due to this risk, your doctor may lower your dosage* if you have liver damage. They’ll also monitor you more closely during treatment.

Kidney problems. Kidney problems may increase your risk of Jakafi side effects. Due to this risk, your doctor may prescribe a lower dosage* of Jakafi if you have a kidney condition. They may also monitor your kidney function during treatment.

Factors that increase your risk of cardiac events. Jakafi treatment may increase the risk of cardiac events such as heart attack in people with certain risk factors. These factors include high blood pressure, diabetes, high cholesterol, and smoking. Your doctor will determine whether Jakafi treatment is safe for you based on your medical and smoking history.

* For information about recommended dosages of Jakafi, see this article.

Alcohol with Jakafi

There are no known interactions between Jakafi and alcohol. If you have questions about drinking alcohol while taking Jakafi, talk with your doctor.

Pregnancy and breastfeeding while taking Jakafi

Your doctor will likely recommend that you do not take Jakafi while you’re pregnant. Clinical trials of Jakafi didn’t include pregnant people. However, in animal studies, Jakafi caused harm in developing offspring.

Talk with your doctor if you’re pregnant or planning to become pregnant before starting Jakafi. They can help determine whether Jakafi is safe for you.

In animal studies, Jakafi was found to pass into breast milk. It’s unknown whether the same thing would happen to people. If you’re breastfeeding or planning to do so, your doctor can advise you on whether Jakafi is safe to take. They can also recommend other treatments for your condition.

Jakafi, like other drugs, can cause side effects. Some of these are mild and may go away over time. Others are serious and require medical attention. If you’d like to learn more about Jakafi, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

Disclaimer:Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.