G-CSF (Granulocyte-colony stimulating factor)

G-CSF (granulocyte-colony stimulating factor) is a type of protein called a growth factor. It is used to help your body make more white blood cells.

What is G-CSF?

G-CSF (granulocyte-colony stimulating factor) is a type of protein called a growth factor. It increases the number of some types of white blood cells in the blood. It can be used with chemotherapy. It can also be used before and after a stem cell transplant.

Different types of G-CSF can be used. These include:

  • lenograstim (Granocyte®)
  • filgrastim (Accofil®, Neupogen®, Nivestim®, and Zarzio®
  • lipegfilgastrim (Lonquex®) 
  • pegfilgrastim (Neulasta®, Pelgraz®, Pelmeg®, and Ziextenzo®).

It is best to read this information with our general information about the type of cancer you have and the treatment you are having.

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

How G-CSF works

G-CSF is made naturally in the body, but it can also be made as a drug. G-CSF stimulates the bone marrow to make more blood cells. Bone marrow is a spongy material inside bones. It is where blood cells are made.

G-CSF is used in two ways. It is given:

  • during treatment with chemotherapy, to stimulate the bone marrow to make white blood cells. These cells are called neutrophils. They help to fight infection. 
  • before a stem cell transplant, to encourage the bone marrow to release stem cells into the blood. The stem cells can then be collected for use in a stem cell transplant. Stem cells are blood cells at their earliest stage.

When G-CSF is used

With chemotherapy

Chemotherapy can lower the number of white blood cells in the blood. The main white blood cells that fight infection are called neutrophils. When they are low, you are neutropenic. This means you are more likely to get an infection.

You may have G-CSF during treatment with chemotherapy so that you are neutropenic for a shorter time. G-CSF is not needed with all types of chemotherapy.

The number of white blood cells usually goes back to a normal level between cycles of chemotherapy. But if white blood cell levels are too low, chemotherapy may have to be delayed or given in a lower dose. G-CSF encourages the bone marrow to make white blood cells. This helps to reduce the risk of infection. It also allows chemotherapy treatments to be given on time and at the planned dose.

Collection for a stem cell transplant

Usually, stem cells stay in the bone marrow while they develop into blood cells. G-CSF encourages the bone marrow to make more stem cells. These cells then move (mobilise) from the bone marrow into the bloodstream. They can then be collected, stored and given back to you when you need them. This is called a stem cell transplant.

You usually have a stem cell transplant as part of high-dose chemotherapy treatment. You have G-CSF before the stem cells are collected from your bloodstream. The cells can then be given back to you after your treatment. They will make new blood cells to replace those you have lost. This is sometimes called high-dose chemotherapy with stem cell support.

You may also have G-CSF after a stem cell transplant. It helps the new stem cells in the bone marrow to recover quicker.

If you are donating stem cells to another person, you will have daily injections of G-CSF for several days. These injections encourage your bone marrow to make stem cells and increase the number of stem cells in the blood.

How G-CSF is given

You usually have G-CSF as an injection under the skin (subcutaneously). A nurse can show you, or a relative or friend, how to inject G-CSF. This means you can have it at home. Sometimes a district nurse or practice nurse can give you the injections.

Some people have G-CSF as a drip into a vein, which takes about 30 minutes. You will have this at the hospital or clinic.

You will have regular blood tests to check the number of white blood cells in your body during your treatment.

With chemotherapy

G-CSF is usually started 24 hours or more after your chemotherapy finishes. You usually have it daily. Your doctor or pharmacist will tell you how many injections you need.

Some types of G-CSF stay in the body for longer. If you are given one of these types, you only need 1 injection after each cycle of chemotherapy.

Stem cell collection

G-CSF is started 4 to 6 days before the planned date for the stem cell collection.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. 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.

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.

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.

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) for more detailed information.

Side effects while treatment is being given

Some people may have side effects while they are being given this treatment or shortly after they have it.

Allergic reaction

Very rarely, some people have an allergic reaction while having this treatment. Signs of a reaction can include:

  • a skin rash
  • feeling breathless
  • problems swallowing
  • swollen lips, face, throat or tongue.

If you have any of these signs, or feel unwell, contact the hospital straight away. Do not take any more of this treatment until you have spoken to your doctor.

Red, itchy skin around injection site

Your skin may become red and itchy around the area where you had the G-CSF injection. Injecting into a different place on your body each time helps to reduce the risk of irritation.

Common side effects

Bone pain

Bone pain is very common. It is caused by your bone marrow making blood cells. You may have some discomfort or a dull ache in some of your bones. It usually affects the bones in your pelvis (between your hips), back, arms or legs. Your doctor can prescribe painkillers, such as paracetamol.


This treatment may cause headaches. If you have headaches, tell your doctor. They may give you painkillers to help.

Bruising and bleeding

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

If the number of platelets is low, you may bruise or bleed easily. You may have:

  • nosebleeds
  • bleeding gums
  • heavy periods
  • blood in your urine (pee) or stools (poo)
  • tiny red or purple spots on the skin that may look like a rash.

Tell your doctor if you have any unexplained bruising or bleeding. You may need a drip to give you extra platelets. This is called a platelet transfusion.

Fever and chills

You may get fever and chills as a side effect of G-CSF. Your doctor may prescribe paracetamol for these symptoms.

G-CSF is often given with chemotherapy. This can increase the risk of getting an infection. If you have any signs of an infection, or feel unwell, contact the hospital straight away. 

Signs of an infection include:

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

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

Sickness or reduced appetite

You may feel sick or not feel like eating while having G-CSF treatment. If this happens, talk to your doctor or nurse. They can give you anti-sickness drugs to help.

Bowel changes

You may be constipated or have diarrhoea while you are having G-CSF treatment. This should get better when treatment stops. Talk to your doctor or nurse if this is a problem for you. Try to drink at least 2 litres (3½ pints) of fluids every day.

Discomfort in the left side or tummy

G-CSF can cause your spleen to get slightly bigger. The spleen is an organ that filters blood and helps fight infection. If you feel discomfort on your left side, in your tummy (abdomen) or in your left shoulder, tell your doctor straight away. Your spleen should go back to its normal size after treatment stops.

Less common side effects

Liver changes

G-CSF may affect how your liver works. This is usually mild and goes back to normal after treatment. You will have blood tests to check how well your liver is working.

Build-up of fluid

This may lead to swelling of the ankles or breathlessness. This is quite rare. Talk to your doctor or nurse if you notice this.

Effects on the lungs

This treatment can cause changes to the lungs. Tell your doctor if you develop:

  • a cough
  • wheezing
  • breathlessness.

You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs.


This treatment may cause you to feel dizzy (light-headed). If you notice this, do not drive or operate any machinery

Other information about G-CSF

Storing G-CSF

Follow any storage instructions given by your pharmacist. Some G-CSF injections should be stored in the fridge. Take the injection out of the fridge 30 minutes before you use it.

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.


Some G-CSF injections contain a sugar called sorbitol. If you have an intolerance to some sugars, talk to your doctor before taking G-CSF.


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.


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

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses 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.

About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert health professionals and people living with cancer.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.