Key takeaways

  • Kisqali is a prescription drug used with other medications to treat certain kinds of breast cancer.
  • More common side effects of Kisqali may include diarrhea, nausea, infection, fatigue, and neutropenia for advanced or metastatic breast cancer.
  • Serious side effects that have been reported in people taking Kisqali include liver damage, interstitial lung disease, and severe skin reactions.

Kisqali (ribociclib) is used in adults to treat breast cancers that are:

Kisqali is prescribed in combination with certain other medications, including Faslodex (fulvestrant) or some aromatase inhibitor drugs. Kisqali is not approved to be used on its own.

Keep reading to learn about the more common, mild, and serious side effects that Kisqali can cause. For a general overview of the drug, including details about its uses and how it works with other drugs, see this Kisqali overview article.

Some people may experience mild or serious side effects during their Kisqali treatment. These can start as soon as you begin treatment with the drug. Kisqali’s common side effects are mild in most people who have them.

When taking for advanced or metastatic breast cancer

More common side effects reported in people taking Kisqali for advanced or metastatic breast cancer include:

For more information about some of these side effects, see “Side effect specifics.”

When taking for early stage breast cancer

More common side effects reported in people taking Kisqali for early stage breast cancer include:

  • infection
  • headache
  • nausea
  • fatigue
  • lymphocytopenia (low levels of lymphocytes, a type of white blood cell)

For more information about some of these side effects, see “Side effect specifics.”

It’s possible you’ll have mild side effects from taking Kisqali, and some are more common than others. Keep in mind that side effects from medications such as Kisqali can vary from person to person.

Mild side effects reported in people taking Kisqali for advanced or metastatic breast cancer include:

Mild side effects reported in people taking Kisqali for early stage breast cancer include:

  • headache
  • nausea
  • diarrhea
  • constipation
  • abdominal pain
  • weakness
  • cough
  • fever
  • infection
  • hair loss
  • fatigue

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

For more information about some of these side effects, see “Side effect specifics.”

Kisqali may cause mild side effects other than the ones listed above. See the Kisqali prescribing information for details.

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 Kisqali, visit MedWatch.

Serious side effects that have been reported in people taking Kisqali include:

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

For more information about some of these side effects, see “Side effect specifics.”

Allergic reaction

Like most drugs, Kisqali (ribociclib) can cause an allergic reaction in some people. In general, symptoms of an allergic reaction can be mild or serious.

Kisqali may cause severe skin reactions. For details, see the “Side effect specifics” section.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. To manage symptoms, they may suggest an over-the-counter (OTC) oral antihistamine, such as Benadryl (diphenhydramine). Or they may recommend a product you apply to your skin, such as hydrocortisone cream.

If your doctor confirms you had a mild allergic reaction to Kisqali, they’ll determine 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 had a serious allergic reaction to Kisqali, they may have you switch to a different treatment.

Below are answers to some frequently asked questions about Kisqali’s side effects.

Why is it best to take Kisqali in the morning?

Kisqali’s manufacturer doesn’t mention why taking the drug in the morning may be best. But there are several reasons why your doctor may suggest that you take Kisqali in the morning.

Taking Kisqali soon after you wake up may lower the risk of difficulty sleeping. This side effect was reported in people taking Kisqali for advanced or metastatic breast cancer. If you typically sleep at night, you may sleep better if you take Kisqali in the morning.

Also, you may be more likely to notice certain side effects if you take Kisqali in the morning. For example, long QT syndrome is a possible (but uncommon) side effect of Kisqali. This condition doesn’t often cause symptoms. However, some people may notice symptoms such as fainting, heart palpitations (a fluttery feeling in the chest), or shortness of breath. It could be easier to spot these symptoms if you take Kisqali in the morning.

If you think you’re having symptoms of long QT syndrome, contact your doctor right away. They’ll likely recommend that you have an EKG and possibly other tests. To learn more, see the “Side effects specifics” section.

Talk with your doctor or pharmacist if you have questions about side effects of Kisqali or when to take it.

Will taking Kisqali with Femara increase my risk of certain side effects?

Possibly. Kisqali is used with other drugs to treat breast cancer. For example, Kisqali may be used with Femara (letrozole), an aromatase inhibitor drug. Or Kisqali may be used with Faslodex (fulvestrant) for advanced or metastatic breast cancer.

In studies, there were some slight differences in side effects depending on which medication people took with Kisqali. For example, people with advanced or metastatic breast cancer who took Kisqali with Femara reported difficulty sleeping as a side effect. But this wasn’t reported by people who took Kisqali with Faslodex. Those who took Kisqali with Faslodex reported dizziness as a side effect, but people taking Kisqali with Femara didn’t.

So your risk of side effects can vary slightly depending on other medications you take with Kisqali. But reported side effects were mainly the same, regardless of which drug was used with Kisqali.

Can Kisqali cause weight gain?

It’s unlikely. In studies, weight gain wasn’t reported by people taking Kisqali.

People who took Kisqali with the drug Femara or an aromatase inhibitor reported edema (fluid retention and swelling). While this side effect can cause some weight gain, it usually goes away as the swelling is treated. If you have edema from taking Kisqali, your doctor can recommend treatment options for it.

Talk with your doctor if you have questions or concerns about your weight during cancer treatment.

Are there lab tests to check for side effects from taking Kisqali?

For some of the side effects Kisqali may cause, your doctor can order certain lab tests. For example, your doctor will likely order regular tests to check your liver health while you’re taking this drug. This helps monitor for liver damage, a possible serious side effect of Kisqali.

Your doctor will likely order other lab tests before you start Kisqali and while you’re taking it. Talk with your doctor to find out more about the tests they’ll order during your Kisqali treatment.

If I have side effects with Kisqali, will I need to stop taking it?

It depends. Whether you keep taking Kisqali after having side effects is a decision you and your doctor will make together. Some of Kisqali’s side effects are severe enough that you may need to stop taking the drug if you experience them.

For example, if you have a serious skin reaction from taking Kisqali, your doctor will likely have you stop treatment. This is because skin reactions caused by Kisqali can be life threatening in rare cases. And these reactions can occur again if you keep taking the drug. (For more information on skin reactions Kisqali may cause, see the “Side effects specifics” section below.)

However, you may be able to keep taking Kisqali if you develop side effects that aren’t bothersome to you. For example, it’s common to have mild nausea while taking Kisqali. But most people who have this side effect are able to keep taking the drug.

Talk with your doctor if you think you’re having side effects from taking Kisqali. They can discuss the options available to you. These may include waiting to see if the side effect goes away or lowering your dose of Kisqali. Or they may suggest switching to another treatment for your cancer.

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

Hair loss

Hair loss or thinning is a possible side effect from taking Kisqali. In studies, this was among the more common side effects. Other medications used together with Kisqali, such as Femara (letrozole) and Faslodex (fulvestrant), can also cause this side effect.

Keep in mind that hair loss is also a side effect caused by many other cancer treatments.

What might help

Talk with your doctor if you have hair loss or thinning while taking Kisqali. To treat it, they may recommend a medication such as Rogaine (minoxidil). Although Rogaine is available over the counter, you should talk with your doctor before using it. They’ll need to check whether it interacts with the medications you’re taking for your cancer treatment.

Besides medications, you could also try some of the following to help you manage hair loss caused by Kisqali:

You can see this article for more information about hair loss caused by cancer treatment. It also provides tips to help manage this side effect.

Fatigue

Some people may experience fatigue (low energy) from treatment with Kisqali. This was a commonly reported side effect in people who took Kisqali with Femara. It wasn’t reported in people who took Kisqali with Faslodex.

Difficulty sleeping was also a side effect reported in people who took Kisqali with Femara, and this can cause or worsen fatigue.

Other side effects that have been reported with Kisqali treatment, regardless of what other drugs were taken with it, can also cause or worsen fatigue. These include:

Keep in mind that cancer itself can cause fatigue.

What might help

Talk with your doctor if you’re experiencing fatigue while taking Kisqali. They can work with you to find the best approach to treating this side effect. You can check out the American Cancer Society website, which also features tips that may help ease this side effect.

Long QT syndrome

Although uncommon, long QT syndrome can happen with Kisqali treatment.

The QT interval is part of your heart’s natural rhythm. In studies, Kisqali caused the QT interval to lengthen. This is known as long QT syndrome. In some people, long QT syndrome doesn’t cause problems or symptoms. But this condition can cause an atypical heartbeat that’s life threatening in rare cases.

Long QT syndrome doesn’t often cause symptoms. But some people may notice the following:

  • fainting
  • heart palpitations
  • shortness of breath

Some people are born with long QT syndrome. But it can also be caused by taking certain medications, including Kisqali.

Certain people have a higher risk of long QT syndrome. Having certain medical conditions or taking certain medications can increase your risk of long QT syndrome during Kisqali treatment. In this case, a doctor may recommend a medication other than Kisqali for your breast cancer.

What might help

Before you start taking Kisqali, your doctor will check your heart rhythm with an electrocardiogram (EKG). You’ll continue having EKGs during your treatment. This can help your doctor detect long QT syndrome before it causes symptoms or becomes severe.

Your doctor will also check your electrolyte levels before you start treatment, and they’ll continue monitoring them during treatment. This is because certain electrolytes, including potassium and magnesium, play an important role in maintaining a healthy heart rhythm.

If you think you’re having symptoms of long QT syndrome, contact your doctor right away. They’ll likely recommend that you have an EKG and possibly other tests.

If you develop long QT syndrome from taking Kisqali, your doctor may temporarily pause your treatment or lower your dose of the drug. Or they may recommend that you permanently stop taking it.

Neutropenia

Neutropenia is the most common side effect reported in studies of people taking Kisqali. With neutropenia, you have low blood levels of neutrophils. These are a type of white blood cell that helps your body fight infection.

This condition can be mild or severe. It’s common to have severe neutropenia while taking Kisqali, regardless of which other medications you take with it. But even when it’s severe, most people are able to keep taking Kisqali.

Neutropenia typically doesn’t cause symptoms. But having low neutrophil levels can increase the risk of getting an infection, including serious infections. So, you may notice symptoms of infection, such as chills or fever.

What might help

Before you start taking Kisqali, your doctor will check your neutrophil levels with a blood test. They’ll continue monitoring these levels during your treatment.

If you have neutropenia as a side effect from Kisqali, your doctor may temporarily pause your treatment or lower your dose of the drug. Or they may recommend that you permanently stop taking it.

When Kisqali treatment is paused, neutrophils tend to return to usual levels within about 12 days.

Severe skin reactions

While rare, Kisqali can cause severe skin reactions. In extreme cases, these reactions can be life threatening. This side effect wasn’t reported in studies of Kisqali, but it has been reported since the drug became available for use.

Severe skin reactions that Kisqali can cause include:

Symptoms of these reactions can include:

  • blisters on your eyes, lips, mouth, or skin
  • fever
  • flu-like symptoms
  • rash that continues to get worse or a severe rash
  • changes in skin color
  • skin burning or pain
  • skin peeling

What might help

If you think you’re having a severe skin reaction to Kisqali, contact your doctor immediately. These reactions can be serious and may require treatment in a hospital. If your symptoms feel life threatening, seek emergency medical attention right away. Call 911 or your local emergency number.

If you have a severe skin reaction from Kisqali, your doctor will pause your Kisqali treatment. Once you receive the treatment for this reaction and it goes away, your doctor may recommend you stop taking the drug permanently.

Kisqali may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Kisqali. The list below includes factors to consider.

  • lung problems, including interstitial lung disease and pneumonitis
  • severe skin reactions
  • use of the drug tamoxifen
  • neutropenia
  • heart problems, including heart failure, slow or irregular heartbeat, or long QT syndrome
  • electrolyte problems
  • active infection
  • liver damage, including hepatitis
  • allergic reaction

Alcohol and Kisqali

There’s no known interaction between consuming alcohol and taking Kisqali. But drinking alcohol could worsen or increase the risk of certain side effects of Kisqali. Examples of these side effects include fatigue, nausea, diarrhea, and headache.

If you drink alcohol, talk with your doctor about how much is safe to consume during your Kisqali treatment.

Pregnancy and breastfeeding while taking Kisqali

Kisqali is not safe to take during pregnancy or while breastfeeding. Based on how the drug works, it could cause fetal harm if taken during pregnancy.

If you’re able to become pregnant, your doctor will give you a pregnancy test before you start taking Kisqali. They’ll also recommend you use birth control while taking Kisqali and for 3 weeks after your last dose.

It’s not known if Kisqali passes into breast milk. But if it does, it’s thought the drug could cause serious side effects in a child who is breastfed. Your doctor will likely recommend that you do not breastfeed while taking Kisqali and for 3 weeks after your last dose.

If you’re pregnant, breastfeeding, or thinking about becoming pregnant or breastfeeding, talk with your doctor before you start Kisqali treatment.

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.