What is palbociclib?

Palbociclib is a type of targeted therapy drug called a kinase inhibitor (blocker). A kinase is a protein that can help cells in the body grow and divide. Palbociclib blocks the kinase protein. This helps to slow cancer growing or spreading.

You take palbociclib with a hormonal therapy drug. Palbociclib works with the hormonal therapy drug to slow the cancer growing and spreading.

During treatment you usually see a cancer doctor, a specialist nurse, or a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

When palbociclib is used

Palbociclib is be used to treat people who have oestrogen receptor positive and HER 2 negative breast cancer. It may be used if the cancer has:

  • spread to the tissues and lymph nodes close to the breast (locally advanced), and surgery is not possible
  • spread from the breast to other parts of the body (metastatic). 

Taking palbociclib capsules

You take one palbociclib capsule every day for 21 days. You then have a break of 7 days when you do not take any palbociclib. After this, you start taking it again in the same way. You carry on taking it in this way for as long as it is working for you.

Take the capsule at the same time each day with food. Swallow the capsule whole with a large glass of water. Do not crush or dissolve capsules. If you find it difficult to swallow your capsules, speak to your doctor or pharmacist.

Always take your capsules and hormonal therapy drug exactly as your nurse or pharmacist explains. This is important to make sure they work as well as possible for you.
Never take a double dose of palbociclib. If you are sick after taking the capsules or if you forget to take them, do not take another dose. Take the next dose at the usual time.

There are some other important things to remember when taking your capsules:

  • Do not eat grapefruit or drink grapefruit juice.
  • Keep the capsules in the original package and at room temperature. 
  • Keep the capsules safe and out of the reach of children. 
  • Return any remaining capsules to the pharmacist if your treatment is stopped.

You will have your blood checked regularly during treatment. A nurse or a person trained to take blood (phlebotomist) will take a blood sample from you. This is to check that your blood cells are at a safe level for you to have treatment. Your doctor will tell you when your blood will be checked.

About side effects

We explain the most common side effects of this treatment here. You may get some of the side effects we mention, but you are unlikely to get all of them.

You take this treatment with a hormonal therapy drug which can cause side effects not listed here. It is best to read this information with our information about the hormonal therapy drug you are having. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) to download a Patient Information Leaflet (PIL) for these drugs. The leaflet lists all known side effects.

Common side effects

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is called neutropenia.

If you have an infection, it is important to treat it as soon as possible. Contact the hospital straight away on the 24-hour contact number you have if:

  • your temperature goes over 37.5°C (99.5F) 
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection.

Symptoms of an infection include:

  • feeling shivery
  • a sore throat
  • a cough
  • diarrhoea 
  • needing to pass urine often.

It is important to follow any specific advice your cancer treatment team gives you.

The number of white blood cells will usually return to normal before your next treatment. You will have blood tests before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time or lower the dose. Your doctor or nurse will tell you how often you need to have your blood tested.

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.


Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy. If you feel sleepy, do not drive or operate machinery.

Feeling sick

Your doctor can prescribe anti-sickness (anti-emetic) drugs to help prevent or control sickness. If you still feel sick, tell your doctor. They can prescribe other anti-sickness drugs that may work better for you.


This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is usual for you, or having watery or loose stools. If you have a stoma, it will be more active than usual.

If you have diarrhoea:

  • try to drink at least 2 litres (3½ pints) of fluids each day
  • avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods
  • contact the hospital for advice.

Changes in taste or loss of appetite

You may lose your appetite or notice taste changes when taking palbociclib. You can ask to see a dietitian or specialist nurse at your hospital if this does not improve. They can give you advice on improving your appetite and coping with taste changes.

Skin changes

This treatment may make your skin become red or feel dry. It can cause a rash, which may be itchy. Always tell your doctor or nurse about any skin changes. They can give you advice and may prescribe creams or medicines to help.

Hair loss

Your hair may get thinner but you are unlikely to lose all the hair from your head. Talk to your nurse if you are worried about this.

Sore mouth

You may get a sore mouth or mouth ulcers. This can make you more likely to get a mouth infection.

Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.

If your mouth is sore:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco, and foods that irritate your mouth.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. 

Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin that may look like a rash.

Some people may need a drip to give them extra platelets. This is called a platelet transfusion.

Changes in the way the liver works

Palbociclib may affect how your liver works. It is important to tell your doctor before you start treatment if you have any liver conditions. You will have blood tests to check how well your liver is working. If you have changes to your liver, your doctor may change the dose of treatment.

Eye problems

Palbociclib may affect your eyes. You may notice they are dry or watery. Speak to your doctor if this is a problem. They may be able to give you something to help. Contact your doctor if you have blurry vision or vision changes.

Other information

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • pain, redness or swelling in a leg or arm
  • breathlessness
  • chest pain.

If you have any of these symptoms, contact a doctor straight away.

A blood clot is serious, but can be treated with drugs that thin the blood. Your doctor or nurse can give you more information.

Other medicines

Some medicines can affect your treatment or be harmful when you are having it. This includes medicines you can buy in a shop or chemist. Tell your cancer doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies.


This drug contains lactose. If you have a lactose intolerance, talk to your doctor before you start taking this treatment.


Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.


Women are advised not to breastfeed while having this treatment. This is because the drugs could be passed to the baby through breast milk.


Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.