What is Palbociclib used for?

hormone receptor positive, HER2 negative breast cancer that is advanced or has spread, given with hormone therapy.

What are the common side effects of Palbociclib?

Low white blood cell counts, which raise your chance of infection. Feeling tired or weak. Feeling sick to your stomach or throwing up. Mouth sores. Hair thinning. Diarrhea. Low red blood cells or platelets.

When should I call my care team while taking Palbociclib?

A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills; Signs of infection, such as a cough, burning when you pee, or a sore that will not heal; New or worse cough, chest pain, or trouble breathing; Unusual bruising or bleeding.

Palbociclib

Say it: pal-boh-SY-klib · Brand names: Ibrance

Palbociclib is a targeted therapy pill that helps stop breast cancer cells from dividing.

What it is

Cancer cells use proteins called CDK4 and CDK6 to divide and make more cells. Palbociclib blocks these proteins. It is given with hormone therapy, and the two work better together.

Often used for

hormone receptor positive, HER2 negative breast cancer that is advanced or has spread, given with hormone therapy

How you get it

Palbociclib is taken by mouth at home, once a day. It is usually taken for 3 weeks, followed by 1 week off, and then repeated. Capsules are taken with food; tablets can be taken with or without food. Your schedule may be different.

Common side effects and what helps

Low white blood cell counts, which raise your chance of infection. Wash your hands often and avoid people who are sick.
Feeling tired or weak. Rest when you need to, and try short walks.
Feeling sick to your stomach or throwing up. Eat small meals and ask your team about anti-nausea medicine.
Mouth sores. Brush gently with a soft toothbrush and rinse with a mild salt water rinse. Avoid spicy foods.
Hair thinning. This usually grows back after treatment.
Diarrhea. Drink plenty of fluids. Tell your team early, since they may give you medicine to help.
Low red blood cells or platelets. You will have blood tests to check.

Call your care team right away if you have

A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills
Signs of infection, such as a cough, burning when you pee, or a sore that will not heal
New or worse cough, chest pain, or trouble breathing
Unusual bruising or bleeding

Before you start, tell your team

If you are pregnant, may become pregnant, or are breastfeeding
If you have an infection or fever
If you have liver or kidney problems
All the medicines, vitamins, and herbal products you take, since some can change how this medicine works

Good to know

You will have blood tests to check your blood counts before each cycle and more often at first.
Rarely, it can cause serious lung inflammation. Tell your team about any breathing changes.
This medicine can harm an unborn baby. Use birth control during treatment and for some time after. Ask your team how long.

At home

Take it at about the same time each day.
Swallow capsules or tablets whole. Do not chew, crush, or open them.
Do not eat grapefruit or drink grapefruit juice while taking this medicine.
If you miss a dose or throw up after taking it, ask your team what to do. Do not take extra pills to make up for it.
Store the pills at room temperature in the original bottle, away from children and pets.

Questions to ask

How long will I take this medicine?
When will I have blood tests?
Is it safe to take my other medicines, vitamins, or supplements with this one?
How will we know if this medicine is working?

Side effect guides

Sources

Quick answers

What is Palbociclib?: Palbociclib is a targeted therapy pill that helps stop breast cancer cells from dividing. Brand names: Ibrance.
What is Palbociclib used for?: hormone receptor positive, HER2 negative breast cancer that is advanced or has spread, given with hormone therapy.
How is Palbociclib given?: Palbociclib is taken by mouth at home, once a day. It is usually taken for 3 weeks, followed by 1 week off, and then repeated. Capsules are taken with food; tablets can be taken with or without food. Your schedule may be different.
What are the common side effects of Palbociclib?: Low white blood cell counts, which raise your chance of infection. Feeling tired or weak. Feeling sick to your stomach or throwing up. Mouth sores. Hair thinning. Diarrhea. Low red blood cells or platelets.
When should I call my care team while taking Palbociclib?: A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills; Signs of infection, such as a cough, burning when you pee, or a sore that will not heal; New or worse cough, chest pain, or trouble breathing; Unusual bruising or bleeding.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.