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Ibrance

by Sama Mohamed · October 3, 2025

Pronunciation: EYE-brans
Generic name: palbociclib
Dosage form: oral tablet, oral capsule
Drug class: CDK 4/6 inhibitors 

What is Ibrance?

Ibrance is used to treat HR-positive, HER2-negative breast cancer that has spread to other parts of the body. Ibrance is used in combination with an aromatase inhibitor as the first hormonal-based therapy, or fulvestrant in those with breast cancer progression following hormonal therapy.

Ibrance’s mechanism of action involves blocking proteins involved in cell division called cyclin-dependent kinases (CDK), specifically CDK 4 and 6, preventing the cancer from dividing and multiplying uncontrollably. HR+ breast cancer cells rely heavily on CDK 4/6 for growth. Ibrance belongs to the drug class CDK 4/6 inhibitors.

Ibrance is a targeted treatment, it is not chemotherapy .

Ibrance gained FDA approval on February 3, 2015. An Ibrance generic is available under the name palbociclib .

Ibrance uses

Ibrance is used to treat HR-positive, HER2-negative advanced or metastatic breast cancer in postmenopausal women or men. Ibrance should always be used in combination with:

  • an aromatase inhibitor (such as anastrozole, exemestane, or letrozole) as initial endocrine-based therapy in postmenopausal women or men; or
  • fulvestrant in patients with disease progression following endocrine therapy.

Ibrance side effects

The most common side effects of Ibrance are:

  • infections
  • tiredness
  • nausea
  • sore mouth
  • abnormalities in liver blood tests
  • diarrhea
  • hair thinning or hair loss
  • vomiting
  • rash
  • loss of appetite
  • low red blood cell counts and low platelet counts. Call your healthcare provider right away if you develop any of these symptoms of low blood cell  during treatment dizziness, shortness of breath, weakness, bleeding or bruising more easily, or nosebleeds

These Ibrance side effects are the most common ones that occur when used with either letrozole or fulvestrant.

Hair loss is not considered a common side effect of Ibrance. Ibrance is more likely to cause hair thinning .

Ibrance may cause fertility problems in males. This may affect your ability to father a child. Talk to your healthcare provider about family planning options before starting Ibrance if this is a concern for you.

Serious side effects and warnings

Ibrance may cause the following serious side effects.

Low white blood cell counts (neutropenia). Low white blood cell counts are very common when taking Ibrance and may cause serious infections that can lead to death. Your healthcare provider should check your white blood cell counts before and during treatment.

If you develop low white blood cell counts during treatment with Ibrance, your healthcare provider may stop your treatment, decrease your dose, or tell you to wait to begin your treatment cycle. Tell your healthcare provider right away if you have signs and symptoms of low white blood cell counts or infections such as fever and chills.

Lung problems (pneumonitis). Ibrance may cause severe or life-threatening inflammation of the lungs during treatment that can lead to death. Tell your healthcare provider right away if you have any new or worsening symptoms, including:

  • chest pain
  • cough with or without mucus
  • trouble breathing or shortness of breath.

Your healthcare provider may interrupt or stop treatment with Ibrance completely if your symptoms are severe.

It is not known if Ibrance is safe and effective in children.

Tell your healthcare provider if you have any side effect that bothers you or does not go away. These are not all of the possible side effects of Ibrance. Call your doctor for medical advice about side effects. You may report side effects to the FDA .

Before taking

Before taking Ibrance, tell your healthcare provider about all of your medical conditions, including if you:

  • have a fever, chills, or any other signs or symptoms of infection
  • have liver or kidney problems
  • have any other medical conditions
  • are pregnant, or plan to become pregnant
  • are breastfeeding or plan to breastfeed.

Pregnancy

Ibrance can harm your unborn baby. Females who can become pregnant should use effective birth control during treatment and for at least 3 weeks after the last dose of Ibrance. Your healthcare provider may ask you to take a pregnancy test before you start treatment with Ibrance.

Males with female partners who can become pregnant should use effective birth control during treatment with Ibrance for at least 3 months after the last dose of Ibrance. Talk to your healthcare provider about birth control methods that may be right for you during this time.

If you become pregnant or think you are pregnant, tell your healthcare provider right away.

Breastfeeding

It is not known if Ibrance passes into your breast milk. Do not breastfeed during treatment with Ibrance and for 3 weeks after the last dose.

How should I take Ibrance?

Take Ibrance exactly as your healthcare provider tells you.

  • Take Ibrance with or without food.
  • Ibrance should be taken at about the same time each day.
  • Swallow Ibrance capsules or tablets whole. Do not chew or crush the capsules or tablets and do not try to open the capsules before swallowing them.
  • Do not take any Ibrance capsules or tablets that are broken, cracked, or that look damaged.

Avoid grapefruit and grapefruit products during treatment with Ibrance. Grapefruit may increase the amount of Ibrance in your blood.

Do not change your dose or stop taking Ibrance unless your healthcare provider tells you.

Ibrance dosage

The recommended initial Ibrance dosage for breast cancer is Ibrance 125 mg 1 time daily with or without food for 21 days followed by 7 days without treatment.

  • Your healthcare provider may adjust your dose based on how well you tolerate Ibrance.
  • Ibrance is taken in combination with an aromatase inhibitor or fulvestrant.  

What happens if I miss a dose?

If you miss a dose of Ibrance or vomit after taking a dose of Ibrance, do not take another dose on that day. Take your next dose at your regular time.

What happens if I take too much Ibrance?

If you take too much Ibrance, call your healthcare provider right away or go to the nearest hospital emergency room.

What other drugs will affect Ibrance?

Tell your healthcare provider about all of the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Ibrance and other medicines may affect each other causing side effects. Especially tell your healthcare provider if you take:

  • CYP3A Inhibitors, such as clarithromycin, diltiazem, erythromycin, fluconazole, ketoconazole, or verapamil. These should not be taken at the same time as Ibrance. If a strong CYP3A inhibitor cannot be avoided, your healthcare provider should reduce the dose of Ibrance
  • CYP3A Inducers, such as glucocorticoids, rifampin, carbamazepine, phenobarbital, and phenytoin. Avoid using these at the same time as Ibrance
  • CYP3A substrates, such as cyclosporin, tricyclic antidepressants, and some chemotherapy agents. The dose of sensitive CYP3A4 substrates with narrow therapeutic indices may need to be reduced when given concurrently with Ibrance.

Avoid grapefruit and grapefruit products.

Know the medicines you take. Keep a list of them to show your healthcare provider or pharmacist when you get a new medicine. This is not a full list of interactions with Ibrance.

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