Key takeaways:
Ibrance (palbociclib) is an oral medication that treats certain types of advanced or metastatic breast cancer. It’s a form of targeted therapy.
Ibrance most commonly causes side effects such as fatigue, diarrhea, and changes in blood cell counts. Mild Ibrance side effects can usually be managed at home.
Serious Ibrance side effects don’t happen often, but they’re possible. Some people report potentially serious infections and lung problems while taking Ibrance. Side effects like these warrant prompt medical attention.
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Ibrance (palbociclib) is a convenient, once-daily oral breast cancer medication. It treats a specific form of breast cancer called hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced or metastatic breast cancer.
Even though it treats cancer, Ibrance isn’t a chemotherapy medication. It’s a type of targeted therapy known as a cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitor. And it’s usually taken in combination with hormone therapy. By blocking CDK 4 and CDK 6 enzymes (proteins), Ibrance helps slow the growth of breast cancer cells.
Ibrance fights cancer with a strategic approach. But it can still cause some relatively significant side effects. Most side effects are mild and manageable, but serious risks are also possible.
Ibrance side effects at a glance
As with all medications, Ibrance can cause side effects. The most common Ibrance side effects include:
Fatigue
Weakness
Nausea
Diarrhea
Lower appetite
Lower blood cell counts
Infections
Mouth sores
Hair loss
Vomiting
Skin rashes
Elevated liver enzymes
Changes in taste
Rare but serious Ibrance side effects include:
Serious infection
Lung inflammation
Blood clots
Here’s a closer look at how to manage 11 notable Ibrance side effects.
1. Fatigue
Fatigue is one of the most common side effects of Ibrance. About 40% of people who took it in clinical studies reported feeling tired.
If you’re feeling tired while taking Ibrance, there are a few things you can try to help boost your energy:
Perform light exercise daily, which can be energizing.
Listen to your body — take short naps or breaks when you feel tired.
Stay well hydrated and eat a nutritious, balanced diet to keep you fueled throughout the day.
Schedule activities when you have the most energy.
Ask people in your inner circle for support managing daily tasks or chores.
Talk to your cancer specialist if tiredness becomes unmanageable while taking Ibrance. They may be able to recommend other ways to manage your energy levels.
2. Diarrhea
Diarrhea is another common side effect of Ibrance. It happened in a quarter of people who took it in initial studies.
If you experience diarrhea while taking Ibrance, there’s a few ways to manage it. At the first sign of a loose stool, you can take an over-the-counter antidiarrheal, such as loperamide (Imodium A-D). It’s also important to stay well hydrated with non-sugary liquids to help replenish lost fluids and electrolytes. Also, try to avoid spicy and greasy trigger foods. They can make diarrhea worse.
Let your cancer specialist know if your diarrhea doesn't resolve within about 24 hours. Depending on how severe the diarrhea is, they may recommend that you temporarily stop taking Ibrance and restart it at a lower dose once the diarrhea goes away.
3. Nausea
Like many other cancer medications, Ibrance can cause nausea. A few tips to help manage nausea from Ibrance include eating more frequent smaller meals, temporarily eating bland foods (like toast or crackers), and relaxing with meditation or deep breathing.
If you’re feeling really nauseous, let your healthcare team know. Cancer specialists are very familiar with anti-nausea medications. They may recommend an anti-nausea medication, such as ondansetron (Zofran) or prochlorperazine, to help combat nausea.
4. Changes in blood cell counts
Ibrance can cause your blood cell counts to drop. This includes your white blood cells, red blood cells, and platelets. Of these, Ibrance has the greatest effect on lowering white blood cell counts.
When your red blood cells or platelets are lower than normal, you may bruise or bleed more easily. When white blood cell counts are lower than normal, it’s easier to get sick. This is also when serious infections can happen — and some can be life-threatening.
Because of these risks, your cancer specialist should check your blood cell counts before you start taking Ibrance. They’ll also want to check them regularly while you’re taking it. If your blood cell counts become too low, your care team may recommend you stop taking Ibrance or lower your dosage.
5. Infection
Because Ibrance causes low white blood cells, it can weaken your immune system. When certain types of white blood cells (called neutrophils) get too low, it can lead to a serious condition called neutropenia. Neutropenia tends to happen after about 2 weeks of taking Ibrance and can last for about a week.
People with neutropenia are at a higher risk of developing a serious infection. Having a fever while you’re neutropenic, also known as febrile neutropenia, is especially serious.
If you develop neutropenia while taking Ibrance, your cancer specialist will likely have you temporarily stop taking it to allow your white blood cell counts to recover. They may also lower your dose. Neutropenia usually happens less frequently over time as you continue to take Ibrance.
You should let your cancer specialist know if you have symptoms of an infection, such as fever, chills, or a new cough. This is especially important if you’re neutropenic, as infections can become serious and need to be treated right away.
It’s also important to try to protect yourself from getting sick while taking Ibrance. Some ways to do this are washing your hands often, wearing a facemask in public places, and avoiding crowded areas and people who are sick.
6. Mouth sores
Ibrance can cause mouth sores and ulcers. This can lead to mouth pain that makes it difficult to eat and drink.
Mouth sores can affect your quality of life. Here are some tips to help manage the discomfort:
Keep your mouth clean and brush your teeth with a soft toothbrush.
Avoid alcohol and acidic or spicy foods.
Avoid crunchy foods that may cut the inside of your mouth.
Stay hydrated.
Try to avoid dry mouth symptoms; consider chewing sugar-free gum or sucking on ice chips.
If mouth sores become hard to tolerate, let your cancer specialist know. They may recommend a magic mouthwash, which is an oral rinse that contains several different soothing medications.
7. Hair loss
In clinical studies, over one-third of people taking Ibrance experienced some degree of hair loss. It’s rare to have total hair loss with Ibrance. Hair thinning is more common.
Keep these tips in mind if you experience hair thinning while taking Ibrance:
Limit hair treatments like chemical hair dyes or straighteners.
Only use shampoos that are labeled as mild, gentle, or sulfate free.
Be gentle when brushing or combing your hair.
Avoid overusing heat styling tools, such as curlers and hair dryers.
Get a haircut in a new style or try a wig.
Wear a scarf or hat on your head to stay warm.
Let your cancer specialist know if you’re concerned about hair loss while taking Ibrance. They may be able to recommend other hair loss treatment options.
Keep in mind: Ibrance isn’t the only possible cause of hair loss. Hormone therapy you’re taking with Ibrance may also contribute to hair loss.
8. Lung-related risks
Rarely, Ibrance can cause interstitial lung disease (ILD). This is a type of lung inflammation. ILD can be life-threatening if it happens.
Let your cancer specialist know if you experience any new or worsening respiratory symptoms, including shortness of breath, cough, or chest pain, while taking Ibrance. They may ask you to temporarily stop taking Ibrance while they assess your lungs.
If you develop severe ILD while taking Ibrance, you’ll likely need to stop taking it altogether.
9. Changes in taste
Ibrance can sometimes cause changes in taste, called dysgeusia. People tend to describe it as a sour, bitter, or metallic taste.
In many cases, your sense of taste will gradually return to normal over time. But if taste changes are bothering you while taking Ibrance, some ways to help manage them include sucking on ice chips, chewing gum or mints, and taking your Ibrance doses with food to help mask the taste.
Because Ibrance can also cause mouth sores, which may make taste changes worse, it’s especially important to maintain good oral hygiene while you’re taking Ibrance. If changes in taste become difficult to manage or start affecting your appetite, let your cancer specialist know. They can help you find ways to feel more comfortable while you’re taking the medication.
10. Blood clots
Ibrance raises the risk of blood clots. While these are rare, it’s good to be on the lookout for signs and symptoms of a possible blood clot. Signs include chest pain, swelling in the hands or feet, and sudden shortness of breath.
If you experience symptoms of a blood clot, call 911 or go to the nearest ER right away. And if you have a history of blood clots, let your cancer specialist know before starting Ibrance.
11. Liver problems
Liver enzymes play a key role in helping the body break down medications. But when liver enzyme levels become too high, this can be a sign of problems such as inflammation or liver damage.
Ibrance can cause elevated liver enzymes in about half of people who take it. More serious liver enzyme elevations are rare.
Your cancer specialist should monitor your liver enzymes along with your blood cell counts. If liver enzymes become too high while taking Ibrance, your cancer specialist may recommend pausing Ibrance and restarting at a lower dose.
When should you contact your cancer specialist about Ibrance side effects?
Many of Ibrance’s side effects are mild and improve on their own over time. But some side effects are serious. Contact your cancer specialist if any side effects are hard to tolerate or worsen at any point.
If you think you're having a serious side effect of Ibrance, seek medical attention right away. Be on the lookout for symptoms such as:
Trouble breathing
Sudden or worsening cough
Chest pain
Bleeding
Fever
Chills
Frequently asked questions
If you’re taking Ibrance, it’s best to skip grapefruit and grapefruit juice. Grapefruit can raise the amount of Ibrance in your body, which may increase your risk of side effects.
Ibrance can also harm a developing fetus. So you shouldn’t become pregnant while taking it. Use effective birth control during treatment and for at least 3 weeks after your last dose.
It’s also recommended to avoid breastfeeding while taking Ibrance and for at least 3 weeks after stopping it. Experts don’t know for sure whether Ibrance passes into breast milk, so it’s safest to wait until the medication is out of your system.
There’s no limit for how many years you can take Ibrance. It's typically taken long-term.
In clinical studies, some participants took Ibrance for more than 2 years — and some stayed consistent with it even longer. It's usually recommended to be continued as long as your cancer doesn’t progress while you’re prescribed Ibrance and you’re not experiencing any intolerable side effects.
Hair usually doesn’t grow back while you’re still taking Ibrance. If you experience hair thinning or hair loss, regrowth often doesn’t happen until after you stop the medication. This is because Ibrance affects rapidly dividing cells, including hair follicle cells, which can interrupt the normal hair growth cycle.
It may take a couple months for hair to regrow after stopping Ibrance. For mild-to-moderate hair loss, you can consider trying a medication such as topical minoxidil (Rogaine), but check with your cancer specialist before doing so.
If you’re taking Ibrance, it’s best to skip grapefruit and grapefruit juice. Grapefruit can raise the amount of Ibrance in your body, which may increase your risk of side effects.
Ibrance can also harm a developing fetus. So you shouldn’t become pregnant while taking it. Use effective birth control during treatment and for at least 3 weeks after your last dose.
It’s also recommended to avoid breastfeeding while taking Ibrance and for at least 3 weeks after stopping it. Experts don’t know for sure whether Ibrance passes into breast milk, so it’s safest to wait until the medication is out of your system.
There’s no limit for how many years you can take Ibrance. It's typically taken long-term.
In clinical studies, some participants took Ibrance for more than 2 years — and some stayed consistent with it even longer. It's usually recommended to be continued as long as your cancer doesn’t progress while you’re prescribed Ibrance and you’re not experiencing any intolerable side effects.
Hair usually doesn’t grow back while you’re still taking Ibrance. If you experience hair thinning or hair loss, regrowth often doesn’t happen until after you stop the medication. This is because Ibrance affects rapidly dividing cells, including hair follicle cells, which can interrupt the normal hair growth cycle.
It may take a couple months for hair to regrow after stopping Ibrance. For mild-to-moderate hair loss, you can consider trying a medication such as topical minoxidil (Rogaine), but check with your cancer specialist before doing so.
The bottom line
Common Ibrance (palbociclib) side effects include low blood cell counts, diarrhea, and fatigue. Be on the lookout for serious side effects too, such as serious infections and lung inflammation. Talk to your cancer specialist for more information about managing Ibrance side effects.
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References
American Cancer Society. (2023). Hormone therapy for breast cancer.
Freites-Martinez, A., et al. (2018). Endocrine therapy–induced alopecia in patients with breast cancer. Journal of the American Medical Association Dermatology.
National Cancer Institute. (n.d.). Definition of neutrophil.
Patel, K., et al. (2017). Febrile neutropenia. Journal of the American Medical Association Oncology.
Pfizer. (2025). Ibrance - palbociclib capsule [package insert].
Thill, M., et al. (2018). Management of adverse events during cyclin-dependent kinase 4/6 (CDK4/6) inhibitor-based treatment in breast cancer. Therapeutic Advances in Medical Oncology.
Verma, S., et al. (2016). Palbociclib in combination with fulvestrant in women with hormone receptor-positive/HER2-negative advanced metastatic breast cancer: Detailed safety analysis from a multicenter, randomized, placebo-controlled, phase III study (PALOMA-3). The Oncologist.
