Ibrance (Palbociclib) – Oral

What Is Ibrance?

Ibrance (palbociclib) is a targeted oral cancer therapy used in combination with other medications to treat hormone receptor-positive (HR+) or human epidermal growth factor 2 (HER2)-negative metastatic breast cancer.

Targeted therapies are not typical chemotherapy drugs. They work by interfering with the action of specific molecules in the cancer cell. Ibrance is the first available drug to target molecules called CDK 4 and CDK 6, which work with estrogen and progesterone receptors to stimulate the growth of breast cancer cells. It is also called a kinase inhibitor. Inhibiting these molecules slows tumor growth.

Ibrance is available by prescription in capsule and tablet forms.

Drug Facts

Generic Name: Palbociclib

Brand Name(s): Ibrance

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Antineoplastic agent

Available Generically: No

Controlled Substance: N/A

Active Ingredient: Palbociclib

Dosage Form(s): Tablet, capsule

What Is Ibrance Used For?

Ibrance is specifically approved to treat breast cancer that is:

  • HR+ that has either estrogen or progesterone receptors
  • HER2 negative
  • Metastatic (cancer that has spread to other parts of the body

Breast cancer is classified according to the types of receptors found on the surface of cancer cells. Receptors are specialized proteins that bind with molecules circulating in the blood and signal cancer cells to grow and divide. For example, cancer cells with estrogen receptors (ER) and progesterone receptors (PR) are called ER positive or PR positive.

HER2 is another important receptor. If you are diagnosed with breast cancer, your healthcare provider will determine your hormone receptor status, which can help determine your treatment and prognosis.

Palbociclib is used in combination with other drugs. For example, it is used with an aromatase inhibitor (such as Femara or Arimidex) in postmenopausal people. In addition, when used with Ibrance, a drug called Faslodex (fulvestrant) can help treat people with breast cancer who have previously received hormonal therapy.

How to Take Palbociclib

Use Ibrance exactly as prescribed by a healthcare provider. Ibrance has recently switched from a gelatin-coated capsule to tablets. The new tablets do not contain gelatin or lactose. You can take these tablets with or without food. However, you should swallow the tablets whole. Do not crush, chew, or break them.

The old Ibrance capsules were dispensed in bottles, but the new tablets come in blister packs with dosing instructions. The dosing schedule will vary depending on whether you take palbociclib with another drug.

The typical dosing schedule is in four-week cycles:

  • If you take palbociclib with an aromatase inhibitor, the aromatase inhibitor is taken once daily. Ibrance is taken once daily, but only for the first three weeks of the cycle.
  • When taken with fulvestrant, take Ibrance once daily for the first three weeks of the four-week cycle. For the last week, you do not take Ibrance. At the end of four weeks, the cycle starts over again. Your healthcare provider will administer fulvestrant to you as an intramuscular injection. You would get three doses in the first month of treatment and one dose a month for each month after that.

Avoid consuming grapefruits or grapefruit-related products while taking Ibrance, as these can affect the medication levels in your blood.

Specialty pharmacy providers often dispense palbociclib, so it may not be available at your regular pharmacy. Your healthcare provider's office can help you find a specialty pharmacy provider that can work with your insurance. In addition, your oncology team will monitor your therapy while taking Ibrance.


Store Ibrance at room temperature (between 68 F and 77 F). Keep the tablets in their original blister pack and not in bottles or pill boxes.

Off-Label Uses

Although Ibrance is approved for breast cancer treatment, healthcare providers can prescribe it for other medical conditions when warranted. Prescribing Ibrance for uses outside of its approved indication is called off-label use.

Ibrance is sometimes prescribed off-label to treat well-differentiated liposarcoma, another type of cancer.

How Long Does It Take Ibrance to Work?

You will take Ibrance until disease progression or until side effects become intolerable.

What Are the Side Effects of Ibrance?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at fda.gov/medwatch or 1-800-FDA-1088.

Common Side Effects

Palbociclib is associated with many important side effects. Low red blood cell counts or platelet counts are common. These problems can manifest as:

  • Dizziness
  • Weakness
  • Shortness of breath
  • Easy bruising or bleeding

Other common side effects include: 

  • Infections
  • Fatigue
  • Rash 
  • Gastrointestinal symptoms such as nausea, loss of appetite, and diarrhea

Ibrance may affect male fertility. Talk with your healthcare provider about family planning options before starting the medication.

Severe Side Effects

A few serious safety risks associated with Ibrance may interrupt or cause you to stop therapy altogether.

Leukopenia (Low White Blood Cell Counts)

Since white blood cells fight infections, low counts may put you at risk of serious infections that may be fatal in some cases. For this reason, you should be vigilant for symptoms of infection, like fevers or chills. Your white blood cell counts will be monitored before and during therapy.

Pneumonitis (Inflammation of the Lungs)

Pneumonitis can be severe or even fatal. Again, watch out for symptoms of pneumonitis, including chest pain, cough, or shortness of breath.

Dosage: How Much Ibrance Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (capsules or tablets):
    • For metastatic breast cancer with letrozole or fulvestrant:
      • Adults—125 milligrams (mg) once a day for 21 days, followed by 7 days without medicine. Your doctor may adjust your dose as needed and tolerated.
      • Children—Use and dose must be determined by your doctor.


Your Ibrance dose may have to be modified if you develop low white blood cell counts or signs of lung inflammation or if you have liver disease.

Missed Dose

If you miss a dose or vomit after taking a dose, skip that day’s dose. Take your next day’s dose at the regular time.

Overdose: What Happens If I Take Too Much Ibrance?

Contact your healthcare provider or the Poison Control Center if you take too much Ibrance. Treatment of an overdose of Ibrance would likely consist of treating the resulting side effects.

What Happens If I Overdose on Ibrance?

If you think you or someone else may have overdosed on Ibrance, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Ibrance, call 911 immediately.


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It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Women must have a pregnancy test before using this medicine. Use an effective form of birth control to keep from getting pregnant during treatment and for at least 3 weeks after your last dose. Males who are using this medicine with female partners who can become pregnant must use effective birth control during treatment and for at least 3 months after the last dose. If you think you or your partner have become pregnant while using the medicine, tell your doctor right away.

If you plan to have children, talk with your doctor before using this medicine. Some men using this medicine have become infertile (unable to have children).

Palbociclib can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.

Interstitial lung disease or pneumonitis can occur while using this medicine. This can be life-threatening and requires immediate medical attention. Check with your doctor right away if you have chest pain, cough, difficulty with breathing, fever or chills while using this medicine.

Do not change your dose or stop using this medicine without checking first with your doctor.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.

What Are Reasons I Shouldn’t Take Ibrance?

People should not take Ibrance if they are:

  • Allergic to palbociclib or another ingredient in Ibrance
  • Pregnant
  • Breastfeeding

If you are able to become pregnant, use effective birth control during treatment and at least three months after stopping treatment. This also goes for males on Ibrance with partners who may become pregnant. Avoid breastfeeding during Ibrance therapy and for at least three weeks after your last dose.

What Other Medications Interact With Ibrance?

There are important drug interactions with Ibrance, so discuss all medications, herbs, and supplements you are taking with your healthcare provider. It may be impossible to avoid all the drugs and supplements which interact with Ibrance. Taking certain medications may require careful monitoring if you are on Ibrance.

Palbociclib is processed in the body by an enzyme called cytochrome P450 3A4. Many drugs affect the activity of this enzyme and can decrease or increase the levels of palbociclib in the blood.

 If you are taking palbociclib, interactions can occur with:

  • Grapefruit products
  • Antibiotics, such as Biaxin XL (clarithromycin) and Ery-Tab (erythromycin)
  • Dilantin (phenytoin)
  • St. John’s wort

What Medications Are Similar?

Ibrance is not a traditional chemotherapy drug; it is called targeted therapy, a type of drug that targets the action of a specific molecule in the cancer cell. Ibrance is the only available therapy that targets the activity of the CDK 4 and CDK 6 molecules.

Other targeted therapies that can be used for breast cancer include Avastin (bevacizumab), which interferes with the growth of blood vessels, and Herceptin (trastuzumab), which blocks the activity of the HER2 receptor. However, Ibrance is only indicated to treat HER2-negative breast cancer and would not be used for the same types of breast cancer as Herceptin.

Frequently Asked Questions

  • What is Ibrance used for?

    Ibrance (palbociclib) is used for the treatment of breast cancer that is hormone receptor-positive (estrogen or progesterone receptor positive), is HER2 negative, and is metastatic (has spread to other parts of the body).

    Ibrance is used in combination with other drugs. For example, in postmenopausal people, it is used with an aromatase inhibitor. It may also be used with a drug called Faslodex (fulvestrant) in people who have previously received hormonal therapy for breast cancer.

  • How does Ibrance work?

    Ibrance is a targeted therapy. Targeted therapies for cancer aren’t typical chemotherapy drugs. They work by interfering with the action of specific molecules in the cancer cell. Ibrance is the first available drug to target molecules called CDK 4 and CDK 6, which work with estrogen and progesterone receptors to stimulate the growth of breast cancer cells.

  • What are the side effects of Ibrance?

    Palbociclib is associated with many side effects, including:

    • Low red blood cell or platelet counts
    • Infections
    • Fatigue
    • Rash
    • Gastrointestinal symptoms

    Severe side effects include inflammation of the lungs (pneumonitis), which can be fatal. Symptoms of pneumonitis include chest pain, cough, or shortness of breath.

How Can I Stay Healthy While Taking Ibrance?

Ibrance is one therapeutic option for metastatic breast cancer, a condition that once had few treatments. 

Make sure you use the medication as prescribed. Ibrance has some important safety risks associated with it; in particular, keep an eye out for symptoms of infections or lung inflammation. Your healthcare team will monitor your treatment.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Ibrance (palbociclib) label.

  2. National Comprehensive Cancer Network. Soft tissue sarcoma.

  3. UpToDate. Palbociclib: drug information.

By Rony Kampalath, MD
Rony Kampalath, MD, is board-certified in diagnostic radiology and previously worked as a primary care physician. He is an assistant professor at the University of California at Irvine Medical Center, where he also practices. Within the practice of radiology, he specializes in abdominal imaging.