What They Are and How to Manage Them

Below are just a few of the more common side effects reported by people who took Jakafi in studies. These side effects can vary depending on what condition the drug is being used to treat.

More common side effects in people taking Jakafi for graft-versus-host disease (GVHD) include:

More common side effects in people taking Jakafi for myelofibrosis and polycythemia vera include:

• headache*
• dizziness
• thrombocytopenia*
• anemia*
• diarrhea

* To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Jakafi. These include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop taking Jakafi unless your doctor recommends it.

Jakafi may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section below.

Serious side effects have been reported with Jakafi. These include:

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.

* To learn more about this side effect, see the “Side effects explained” section below.
† Jakafi belongs to a group of drugs called kinase inhibitors. While these side effects weren’t reported in Jakafi studies, they did occur with another kinase inhibitor. Talk with your doctor about your risk of these side effects with Jakafi.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Jakafi, visit MedWatch.

Get answers to some frequently asked questions about Jakafi’s side effects.

Does Jakafi cause long-term side effects?

Yes, in rare cases Jakafi may cause long-term side effects. Long-term side effects refer to those that happen during treatment and continue, or they may start after you’ve stopped taking the drug. Examples of possible long-term side effects include:

Ask your doctor about your risk for these side effects. They can also tell you how long these side effects may last and ways to lower your risk.

* Jakafi belongs to a group of drugs called kinase inhibitors. While these side effects weren’t reported in Jakafi studies, they did occur with another kinase inhibitor. Talk with your doctor about your risk of these side effects with Jakafi.

Will I experience side effects when stopping Jakafi?

It’s possible in certain rare cases. In studies of Jakafi, stopping or lowering the dose of the drug led to worsening of blood cancer symptoms in some people. Symptoms may include:

Your doctor will monitor you carefully for side effects while you’re taking Jakafi. If they need to lower your dose or have you stop the medication, they’ll do it slowly and watch you for serious side effects.

Do not stop taking Jakafi without talking with your doctor first. They can provide more information about the risks of stopping this medication.

Learn more about some of the side effects Jakafi may cause.

Headache

Jakafi may cause headache in some people. This was a common but mild side effect of the drug reported in studies. Headache may have other causes. For example, it may be caused by another side effect of Jakafi, such as anemia (a low level of red blood cells).

What might help

Headache is usually a mild but temporary side effect of Jakafi. But if you have headaches that are bothersome or ongoing, call your doctor. They can determine the cause and discuss ways to manage it.

Do not take any over-the-counter (OTC) medications without talking with your doctor or pharmacist first. They can tell you what’s safe to take for your headache.

Muscle spasms

Jakafi can cause muscle spasms. This was a mild side effect reported by people taking the drug in studies. In most cases this should go away as you continue taking Jakafi. Keep in mind, there may be other causes for muscle spasms, such as an injury, or it may be a side effect of other drugs you take.

What might help

If you’re having bothersome muscle spasms during your Jakafi treatment, call your doctor. They can discuss your symptoms with you and suggest ways to manage the spasms. Do not take OTC medication to treat muscle spasms without checking with your doctor or pharmacist first.

Anemia

In studies of Jakafi, anemia (a low level of red blood cells) was a common but serious side effect of the drug. With anemia you have a lower number of red blood cells circulating in your bloodstream. Symptoms of anemia include:

What might help

Before you start taking Jakafi, your doctor will order a complete blood count (CBC). Then they’ll order blood tests every 2 to 4 weeks until your dosage of Jakafi is consistent. They’ll continue to monitor your blood cell counts periodically for as long as you’re taking this medication.

If you experience symptoms of anemia, call your doctor. They’ll likely order tests to confirm whether your blood cell counts are low. If so, they may lower your dose or temporarily have you stop Jakafi until your blood cell counts recover. For serious anemia, they’ll recommend treatment options such as blood transfusions, if necessary.

Talk with your doctor if you have questions about this side effect.

Thrombocytopenia

Jakafi can cause low blood cell counts, including thrombocytopenia. This is a serious but common side effect reported in the drug’s studies. With this condition, you have a low level of platelets in your bloodstream. Platelets help with blood clotting to slow or stop bleeding.

Symptoms of thrombocytopenia can include:

What might help

Your doctor will check your blood cell counts before you start and throughout your treatment with Jakafi. If you have symptoms of thrombocytopenia, call your doctor right away. They’ll diagnose your condition and treat your low blood cell counts if needed. In some cases, they may lower your dose of Jakafi or stop it temporarily. This can help improve your blood cell counts.

If you have questions about this side effect of Jakafi, talk with your doctor.

Allergic reaction

Like most drugs, Jakafi can cause an allergic reaction in some people. Symptoms can be mild to serious and can include:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)
• swelling under your skin (usually in your eyelids, lips, hands, or feet)
• swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

• an antihistamine you swallow, such as Benadryl (diphenhydramine)
• a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Jakafi, they’ll decide if you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Jakafi, they may have you switch to a different treatment.

Keeping track of side effects

During your Jakafi treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

• what dose of the drug you were taking when you had the side effect
• how soon you had the side effect after starting that dose
• what your symptoms were
• how your symptoms affected your daily activities
• what other medications you were taking
• any other information you feel is important

Taking notes and sharing them with your doctor will help them learn more about how Jakafi affects you. They can then use this information to adjust your treatment plan if needed.

Jakafi may not be right for you if you have certain medical conditions. This is known as a drug-condition interaction. Other factors may also affect whether Jakafi is a good treatment option for you. Talk with your doctor about your health history before starting this medication. Factors to consider include those described below.

Liver problems. If you have serious liver problems, including liver failure, tell your doctor. They may have you take a lower dose of Jakafi to help avoid side effects from the drug. They may also check your blood counts more often to monitor your risk of serious blood-related side effects from the drug.

Kidney problems. Tell your doctor if you have serious kidney problems, including end-stage renal disease (ESRD) before starting treatment with Jakafi. Your doctor may have you take a lower dose to help avoid serious side effects from the drug.

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

Hepatitis B. Tell your doctor if you have or have had hepatitis B. If you currently have hepatitis B, your doctor will likely not have you start Jakafi until the infection has been treated and resolved.

Jakafi can reactivate the virus in some cases. Reactivation means the virus that’s already in your body becomes active again and causes symptoms of hepatitis B.

If you’ve had hepatitis B in the past, your doctor will determine whether this drug is safe for you. They may order a test to check for this condition before prescribing Jakafi for you. If they do prescribe the drug, they’ll monitor you closely for hepatitis B and recommend treatment if you develop symptoms.

Tuberculosis. Tell your doctor if you have or have had tuberculosis (TB) or have a high risk for it. If you currently have TB, your doctor will likely not have you start Jakafi until the infection has been treated and resolved.

Jakafi can increase your risk of TB reactivation if you’ve had TB in the past. Reactivation means the TB bacteria that’s in your body becomes active again and causes symptoms of the condition.

Your doctor may order a TB test before prescribing Jakafi for you and will then determine if the drug is safe. They’ll also monitor you closely for signs of TB while you’re taking the drug and recommend treatment if you develop TB symptoms. If you develop TB, they’ll determine whether it’s safe for you to continue taking Jakafi.

Heart-related problems. Taking Jakafi may increase your risk of certain heart-related problems such as heart attackand stroke. Your risk may be higher if you already have heart problems or other risk factors of heart disease. These include:

Tell your doctor if you already have a heart condition or other risk factors such as diabetes. They’ll discuss the safety of Jakafi for you.

Alcohol and Jakafi

There are no known interactions between alcohol and Jakafi. But Jakafi can increase liver enzyme levels. And drinking too much alcohol could worsen liver-related problems.

If you plan to drink alcohol while taking Jakafi, ask your doctor how much, if any, is safe.

Pregnancy and breastfeeding with Jakafi

It’s not known whether Jakafi is safe to take during pregnancy. If you’re pregnant or planning to become pregnant, ask your doctor if the drug is safe.

It’s not known if Jakafi passes into breast milk. However, there is a risk of serious blood-related side effects from Jakafi, including thrombocytopenia and anemia (a low level of red blood cells). Because of this risk, your doctor will likely suggest not breastfeeding your child during your Jakafi treatment and for 2 weeks after your last dose. They’ll suggest other ways to feed your child.

Jakafi can cause mild to serious side effects which have been reported in studies of the drug. And some serious side effects may be long term. If you have questions about side effects this drug can cause, talk with your doctor. Examples to help get you started include:

• Does my risk of side effects depend on my dosage of Jakafi?
• Do I have a higher risk of blood-related side effects if I already have anemia (a low level of red blood cells)?
• How do side effects of Jakafi compare with those of Hydrea (hydroxyurea)?

To learn more about Jakafi, see these articles:

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Disclaimer: Healthline 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.