Zejula (niraparib) is a prescription drug that’s used to treat certain types of ovarian cancer. Zejula can cause side effects that range from mild to serious. Examples include fatigue, nausea, and constipation.

Specifically, Zejula is prescribed to adults for maintenance treatment* of certain ovarian cancers. The cancer must have responded to a past first treatment with platinum-based chemotherapy. (Chemotherapy refers to traditional drugs used to treat cancer.)

The cancers Zejula is prescribed to treat are:

  • advanced epithelial cancer of the ovaries, fallopian tubes, or peritoneum (lining of the abdomen)
  • recurrent epithelial cancer of the ovaries, fallopian tubes, or peritoneum with BRCA gene mutation†

* Here, “maintenance treatment” refers to therapy to help maintain your body’s response to the past and first treatment.
† “BRCA gene mutation” is a specific and irregular change in a gene.

Zejula comes as an oral tablet. It also comes as an oral capsule, though this is being phased out. Both the capsules and the tablets contain the active ingredient niraparib. (An active ingredient is what makes a drug work.)

Keep reading to learn about the common, mild, and serious side effects that Zejula can cause. For a general overview of the drug, including details about its uses, see this article.

Below are just a few of the more common side effects reported by people who took Zejula in its tablet studies and capsule studies. Not everyone will have these side effects. These side effects can vary depending on which condition the drug is treating.

More common side effects in people taking Zejula for maintenance treatment of advanced ovarian cancer* include:

  • low platelet, red blood cell, and white blood cell counts
  • nausea and vomiting
  • constipation
  • fatigue (low energy)
  • muscle pain

More common side effects in people taking Zejula for maintenance treatment of recurrent ovarian cancer* with BRCA gene mutation include:

  • nausea and vomiting
  • constipation
  • low platelet, red blood cell, and white blood cell counts
  • fatigue
  • headache

* Here, “ovarian cancer” includes epithelial cancer of the ovaries, fallopian tubes, or peritoneum.

Mild side effects have been reported with Zejula in its tablet studies and capsule studies. These include:

  • nausea and vomiting
  • constipation or diarrhea
  • fatigue
  • muscle or back pain
  • headache
  • dizziness
  • difficulty sleeping
  • shortness of breath and cough
  • skin rash
  • taste problems and decreased appetite
  • heartburn
  • dry mouth
  • urinary tract infection (UTI)
  • common cold symptoms
  • mild allergic reaction*†

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

Zejula may cause mild side effects other than those listed above. See the drug’s tablet prescribing information and capsule prescribing information.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Zejula, but it’s not clear whether this side effect occurred in studies.

Serious side effects have been reported with Zejula in its tablet studies and capsule studies. These include:

If you develop serious side effects while taking Zejula, 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.
† An allergic reaction is possible after taking Zejula, but it’s not clear whether this side effect occurred in studies.

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

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

Does Zejula cause long-term side effects?

It’s possible. Long-term side effects include those that may start at any time you’re taking a drug, even if you’ve taken it for a long time. It also includes side effects that may not go away even after you stop taking the drug.

Examples of long-term side effects reported in Zejula’s tablet studies and capsule studies include:

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

Talk with your doctor or pharmacist if you’re concerned about possible long-term side effects from Zejula.

Is hair loss or weight gain a possible side effect of Zejula?

Zejula’s tablet studies and capsule studies did not report weight gain or hair loss.

Zejula can cause taste problems and decreased appetite. So you may experience weight loss while taking this medication. Report any weight loss to your doctor, especially if you also:

These symptoms may be signs of bone marrow problems and may require immediate treatment.

After chemotherapy, it takes about 3–6 months for hair to regrow. You’ll usually begin Zejula treatment 8–12 weeks after chemotherapy. With this overlap, any hair loss after starting Zejula might be from the chemotherapy, not Zejula.

If you are concerned about weight changes or hair loss while taking Zejula, talk with your pharmacist or doctor.

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

Bone marrow suppression

Bone marrow suppression was a common side effect reported in Zejula’s tablet studies and capsule studies. Bone marrow suppression may cause symptoms such as:

  • fatigue
  • weakness
  • bleeding or bruising easily
  • weight loss
  • fever
  • blood in your urine or blood in your stool
  • shortness of breath
  • frequent infections
  • low levels of red blood cells, white blood cells, and platelets

Rarely, bone marrow suppression may lead to certain types of cancers. These include MDS and AML. Studies reported that these cancers can develop about 3.6 months after beginning Zejula and up to 6 years after taking it.

Some factors can increase the risk of bone marrow suppression when taking Zejula. These include:

  • treatment with other medications that suppress bone marrow, such as chemotherapy or high dose steroids
  • a history of radiation treatment
  • a history of bone marrow problems
  • HIV

What might help

If you have symptoms of bone marrow suppression during Zejula treatment, talk with your doctor right away. They’ll likely recommend stopping Zejula and monitoring blood tests to find out whether your bone marrow activity recovers. If the bone marrow does not recover within 28 days, your doctor likely will send you to a blood specialist and not prescribe Zejula again.

High blood pressure

High blood pressure was a common side effect reported in Zejula’s tablet studies and capsule studies. High blood pressure may cause symptoms such as:

  • irregular or fast heart rate
  • pounding in the head, neck, or chest
  • dizziness
  • headache
  • nosebleed
  • chest pain
  • shortness of breath

Factors that can increase the risk of high blood pressure when taking this drug include:

  • excess sodium in your diet
  • lack of sleep
  • smoking
  • excess alcohol consumption

What might help

When starting Zejula, it’s best to monitor your blood pressure and heart rate at least weekly. This should continue for the first 2 months of treatment.

Some things can help lower your blood pressure. These include:

  • eating a balanced diet
  • drinking plenty of water
  • getting enough sleep
  • stopping smoking, if applicable
  • limiting alcohol, if applicable

If you have symptoms of high blood pressure during Zejula treatment, talk with your doctor right away. They’ll likely recommend an urgent medical evaluation and prescribe medication to lower your blood pressure.

Allergic reaction

Like most drugs, Zejula can cause an allergic reaction in some people. But it’s not clear whether this side effect occurred in Zejula’s tablet studies and capsule studies.

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 oral antihistamine, 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 Zejula, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty 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 Zejula, they may have you switch to a different treatment.

Keeping track of side effects

During your Zejula treatment, consider making notes about 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

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

Below is important information you should consider before taking Zejula.

Warnings

Zejula can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Zejula is a good treatment option for you.

Talk with your doctor about your health history before you take Zejula. Be sure to tell them if any of the following factors apply to you:

Alcohol and Zejula

No interactions between alcohol and Zejula are known. But Zejula can cause nausea, vomiting, headache, and dizziness, and alcohol may make these symptoms worse.

Also, increased blood levels of liver enzymes may occur with Zejula, and alcohol use might worsen this effect.

If you have questions about consuming alcohol during Zejula treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Zejula

Zejula is usually prescribed for someone who’s pregnant only if the benefits of treatment outweigh the potential risks to the fetus.

Similarly, Zejula is usually prescribed for someone who’s breastfeeding only if the benefits of treatment outweigh the potential risks to the child.

Pregnancy

Zejula is not safe to take during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options.

If you’re able to become pregnant, your doctor will recommend using a form of birth control during your Zejula treatment. They’ll likely recommend using it before taking Zejula and throughout your treatment. You may also need to continue using it for 6 months after your Zejula treatment ends.

Breastfeeding

Zejula is not safe to take while breastfeeding and for up to 1 month after stopping treatment. If you’re breastfeeding or planning to do so, talk with your doctor about your options.

Like most drugs, Zejula can cause a number of side effects that range from mild to serious. Some are temporary and go away after a few days to weeks. Others may be longer lasting. If you have questions about side effects that Zejula can cause, talk with your doctor.

Examples of questions to help get you started include:

  • What is my risk of developing serious side effects from Zejula?
  • How should I manage nausea and vomiting from Zejula?
  • How can I manage fatigue from Zejula?
  • What side effects should prompt me to contact you?

To learn more about Zejula, see this “All About Zejula” article.

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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.