9 Kisqali Side Effects and How to Manage Them

You’ve been diagnosed with breast cancer. And you find out it’s hormone receptor-positive. This is a familiar scenario — it’s the most common type of breast cancer.

“Hormone receptor-positive” breast cancer means that your cancer cells have proteins called estrogen or progesterone receptors on them. Estrogen and progesterone are hormones that attach to these receptors and tell the cells to grow. This can cause uncontrolled growth and result in tumors.

Thankfully, many treatments can block these effects. Aromatase inhibitors (AIs), such as Arimidex (anastrozole) and Femara (letrozole), block estrogen production. Medications like Faslodex (fulvestrant) break down estrogen receptors and make them disappear. 

But it’s a complicated process, and sometimes we need additional medications to help out. Cyclin-dependent kinase (CDK) 4/6 inhibitors such as Kisqali (ribociclib) block cancer growth using a different approach. The combination is more effective than taking AIs or fulvestrant alone.

If you have advanced or metastatic breast cancer (cancer that has spread to other parts of the body), Kisqali could be part of your treatment plan. We’ll explore some of the most common side effects so you can decide if it’s an option for you.

Kisqali side effects at a glance

Everyone responds to Kisqali uniquely. But there are some common Kisqali side effects that you should be aware of. These include:

• Decreased white blood cells

• Decreased red blood cells

• Decreased platelets (blood cells that clot your blood)

• Increased liver enzymes

• Nausea and vomiting

• Increased creatinine (evaluated via a blood test that measures kidney function)

• Tiredness

• Diarrhea

• Headache

• Constipation

• Hair loss or thinning

• Cough

• Rash

• Back pain

• Low blood glucose (sugar)

Rare but more serious Kisqali side effects include:

• Lung inflammation (interstitial lung disease)

• Serious skin reactions

• Heart rhythm changes

• Serious infection

Let’s dig a little deeper into nine key Kisqali side effects and how to manage them.

EXPERT PICKS: WHAT TO READ NEXT

• Breast cancer treatment options: Countless medications can treat breast cancer, including chemotherapy, targeted therapy, hormone therapy, and immunotherapy.

• A breast cancer journey: One woman describes what it’s like to be diagnosed with and live with breast cancer. 

• Receptor rundown: Identify different types of breast cancer receptors and how they affect the best treatment for you.

1. Low blood cell counts

Kisqali can decrease the amount of the three major blood cells in your body: neutrophils, red blood cells, and platelets. Decreased neutrophils are the most common. Neutrophils are white blood cells that help fight infection. When these go below a certain threshold (neutropenia), you’re at increased risk of getting an infection.

The risk of neutropenia is why Kisqali has a built-in break in its dosing schedule. It’s typically given for 3 weeks at a time, and then you take a 1-week break before restarting it. This is done to ensure that your neutrophils don’t dip too low.

Even with this break, over 70% of people still experienced neutropenia in clinical studies. You’re most likely to get neutropenia within the first 2 months of starting Kisqali. Because of this, your oncology team will monitor your blood counts through regular blood draws.

There isn’t much you can do to prevent neutropenia otherwise. Your oncology team will likely make the necessary dose adjustments if your neutrophils are too low. They also may ask you to stop taking Kisqali for a short period of time to give your neutrophils time to recover. 

Good to know: You can still take steps to prevent infection if you develop neutropenia. Use good infection prevention practices and be sure to report any fevers over 100.4℉ to your oncology team.

2. Increased liver enzymes

Liver enzymes (proteins) play an important role in your body, including breaking down medications. But when your liver enzymes are higher than normal, this can be a sign of liver inflammation or damage. Kisqali causes liver enzyme elevations in about half of people who take it. Serious liver enzyme elevations are more rare.

Your oncology team should monitor your liver enzymes along with your blood counts. You can also help out by avoiding medications and substances known to irritate your liver, such as Tylenol (acetaminophen) and alcohol.

3. Heartbeat changes

QT prolongation is a condition that can lead to abnormal heartbeats, or arrhythmias. Certain medications, including Kisqali, can make QT prolongation more likely. The risk is further increased when you combine Kisqali with other medications that also cause QT prolongation.

Before you start Kisqali, your oncology team should order an electrocardiogram (ECG) to measure the electrical activity of your heart. This will tell them if it’s safe for you to start Kisqali. Your team will also closely monitor your electrolytes, or substances in your blood that help control heart function. If they’re too low, you’ll likely be asked to take a supplement to replenish them.

Good to know: You shouldn’t take Kisqali with tamoxifen, another breast cancer medication. Adding tamoxifen to the mix significantly increases QT prolongation risks.

4. Stomach upset

Nausea is another common side effect of Kisqali. It’s usually mild, though. 

To be safe, your oncology team will likely prescribe you an antinausea medication such as Compazine (prochlorperazine) or Reglan (metoclopramide) to have on hand.

There are a few non-medication-related things you can do to help relieve nausea, too. These include:

• Taking Kisqali with food (you can take with or without, but food may help)

• Avoiding large meals

• Avoiding spicy, fried, or high-fiber foods

• Drinking peppermint or ginger tea

Uncontrolled nausea and vomiting can lead to dehydration. Let your oncology team know if you are still struggling with symptoms even after trying the suggestions above. You may need to receive IV hydration if you’re having trouble keeping fluids and foods down.

5. Fatigue

Fatigue is a common side effect of many cancer treatments — Kisqali is no exception. There is no quick fix for fatigue, but there are a few things you can try to improve fatigue:

• Practice good sleep hygiene by avoiding screens at night, making sure your bedroom is cool and comfortable, and avoiding caffeine late in the day.

• Take short naps throughout the day.

• Try light exercise, like yoga or walking, to boost your energy levels.

Let your oncology team know if you’re so fatigued that you can’t perform normal daily activities such as cooking and showering. They may need to pause your Kisqali prescription.

6. Headache

Headaches are another possible side effect of Kisqali. Headache is a pretty common ailment outside of cancer treatment, so there are plenty of options to ease this pain. These include:

• Drinking enough water

• Making sure you get enough sleep

• Trying an over-the-counter (OTC) pain reliever, such as Advil (ibuprofen)

Talk to your oncology team to see if they recommend a specific OTC pain reliever. Medications like Advil and aspirin can increase your bleeding risk and aren’t preferred if you already have low platelet levels. Tylenol is OK to use instead as long as you’re not having any liver-related side effects.

Reach out to your oncology team right away if your headache isn’t relieved with typical OTC medications, feels unusually severe, or is associated with numbness or vision loss.

7. Hair thinning

Kisqali can cause hair loss, but it’s usually not severe. About a third of people who take Kisqali see some thinning.

There are a few things you can try to minimize hair loss. These include:

• Sleeping on a silk or satin pillowcase

• Using a wide-tooth comb

• Avoiding excessive brushing or pulling on your hair (including tight ponytails or braids)

• Avoiding the use of flatirons and curling irons

8. Skin reactions

Rashes are an unfortunate side effect of many medications. Kisqali has the potential to cause a rash in nearly a quarter of people who take it. 

These rashes are mild in most cases. But they can develop into something more serious. Severe skin reactions include conditions such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS). These conditions are associated with fever, blistering or peeling skin, and rashes that spread to the inside of your mouth.

You should call your oncology team any time you experience a rash. Serious rashes can start small, so it’s a good idea for your team to proactively evaluate it. If they decide it’s mild, a topical corticosteroid cream like hydrocortisone can help. However, symptoms of SJS, TEN, or DRESS are medical emergencies and should be treated immediately in the ER.

9. Lung problems

Kisqali can rarely cause a type of lung inflammation called interstitial lung disease (ILD). 

There isn’t much you can do to prevent this from happening. If you develop new or worsening respiratory symptoms, such as shortness of breath or cough, you should let your oncology team know immediately. They’ll want to get an X-ray or scan of your lungs to confirm ILD. If confirmed, the best course of action is to stop Kisqali. Your team will let you know when (or if) it’s safe to start Kisqali again.

Why trust our experts?

Written by:

Rachel Feaster, PharmD, BCOP, BCPS

Rachel Feaster has over 10 years of professional experience in ambulatory, inpatient, pharmacogenomics, and oncology care. She is board certified in oncology and pharmacotherapy.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Vanessa Carranza, PharmD

Vanessa Carranza, PharmD, is a pharmacist who has dedicated her career to the advancement of medical education for healthcare providers, patients, and caregivers, most notably in the oncology space.

Our editorial standards

Meet our experts