Granulocyte colony stimulating factor (G-CSF)

G-CSF is a type of growth factor. You might have G-CSF after chemotherapy to help your white blood cells recover after treatment. Or you might have it before and after a stem cell transplant.

There are different types of G-CSF, including:

  • lenograstim (Granocyte)
  • filgrastim (Neupogen, Zarzio, Nivestim)
  • long acting (pegylated) filgrastim (pegfilgrastim, Neulasta, Pelmeg, Ziextenco) and lipegfilgrastim (Lonquex)

How does G-CSF work?

Growth factors are proteins made in the body. Some of them make the bone marrow produce blood cells. G-CSF is a type of growth factor that makes the bone marrow produce more white blood cells so it can reduce the risk of infection after some types of cancer treatment.

G-CSF also makes some stem cells move from the bone marrow into the blood. Stem cells are very early cells that develop into red blood cells, white cells and platelets.

Before a stem cell transplant, you have G-CSF to stimulate the bone marrow to produce stem cells and release them into the blood. The stem cells are collected and then you have high dose chemotherapy.

The high dose of chemotherapy stops your bone marrow producing blood cells. So you have the stem cells infused back into your bloodstream. They go into the bone marrow and start making the different types of blood cells again. 

How do you have G-CSF?

You usually have G-CSF as an injection under the skin. 

You usually have injections under the skin (subcutaneous injection) into the stomach, thigh or top of your arm.

You might have stinging or a dull ache for a short time after this type of injection, but they don't usually hurt much. The skin in the area may go red and itchy for a while.

The video below shows you how to inject just under your skin (subcutaneously). 


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

What are the side effects of G-CSF?

Side effects can vary from person to person. They also depend on what other treatment you are having. 

When to contact your team

Your doctor, nurse, or pharmacist will go through the possible side effects. They will monitor you closely during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects, but you might have some of them at the same time.

You usually have G-CSF after chemotherapy, so it’s not always clear if the side effects are caused by G-CSF or chemotherapy.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10 %). You might have one or more of them. They include:

Bone or muscle pain 

You might experience pain in your bones or muscles. Speak to your doctor as they can prescribe medicine to help. 


Tell your healthcare team if you keep getting headaches. They can give you painkillers to help.

Tiredness and weakness (fatigue)

Tiredness and weakness (fatigue) can happen during and after treatment. Doing gentle exercises each day can keep your energy up. Don't push yourself, rest when you start to feel tired and ask others for help.

Bruising, bleeding gums or nosebleeds

This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. You may have nosebleeds or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae).

Breathlessness and looking pale

You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.


Contact your advice line if you have diarrhoea. For example, 2 or more extra loose bowel movements than usual each day. If you have a stoma, you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.

Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain fibre. But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables. 

Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.

High temperature (fever)

If you get a high temperature, let your healthcare team know straight away. Ask them if you can take paracetamol to help lower your temperature.

Hair thinning

Your hair may thin but you’re unlikely to lose all your hair. This usually starts after your first or second cycle of treatment. It is almost always temporary and your hair will grow back when you finish your treatment.

Sore mouth, throat, gut and back passage

It may be painful to swallow drinks or food . Or you might also have diarrhoea and pain if your bowel is inflammed.This can be caused by inflammation of the mucosa (thin lining of the internal organs).

Painkillers can help to reduce the soreness. And mouth washes can help keep your mouth healthy. There might also be numbing gel you could use for your back passage when having a poo.

Let your healthcare team know if you notice any of these symptoms.

Liver changes 

You might have liver changes that are usually mild and unlikely to cause symptoms. They usually go back to normal when treatment finishes. You have regular blood tests to check for any changes in the way your liver is working.

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

  • enlarged spleen and liver - this might cause tummy (abdominal) pain

  • swollen hands and feet (oedema)

  • reddening of the skin and rash. Rarely the rash might be bumpy. Tell your team if this happens, they might be able to give you some medicine to help.

  • constipation

  • difficulty sleeping (insomnia)

  • breathlessness and cough - rarely this could be due to scarring, stiffening or inflammation of the lungs, or a drop in the levels of oxygen in the blood

  • pain or difficulty passing urine

  • increased risk of getting an infection

  • loss of appetite

  • tingling or numbness of the hands or feet (paraesthesia) loss of feeling of sensitivity, especially in the skin (hypoaesthesia)

  • high levels of an enzyme in your blood that can be a sign of injury to your body’s tissues – you have regular blood tests to check this

  • high or low blood pressure – you might have headaches or feel faint

  • muscle spasms

  • generally feeling unwell

  • chest pain

  • pain

  • a reaction during the infusion – you might get a rash, shortness of breath, redness or swelling of the face and dizziness – tell your team straight away

  • nosebleed

  • coughing up blood

  • dizziness

  • tummy pain

Rare side effects

This side effects happens in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:

  • rejection of transplanted bone marrow (graft versus host disease)

  • leaking of fluid and proteins out of the blood vessels into the tissues (capillary leak syndrome)

  • high uric acid levels in the blood that may cause gout – you have regular blood tests to check this

  • blockages of the small veins in the liver causing liver damage

  • inflammation around the drip site

  • changes in your lungs including fluid on the lungs and bleeding

  • high levels of enzymes in the blood that could be a sign of liver damage – you have regular blood tests to check this

  • thinning of the bones which can make the bones weaker and easier to break (osteoporosis)

  • small amounts of protein found in your urine

  • severe pain in the bones, chest, gut or joints (sickle cell anaemia with crisis)

  • plum coloured, raised, painful sores on the your legs or arms and sometimes the face and neck with a high temperature (Sweets syndrome)

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do you need to know?

Other medicines, foods and drink 

Cancer drugs can interact with medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.

Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.

Pregnancy and contraception

This treatment might harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for a few months afterwards.

Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant while having treatment.


It is not known whether this treatment affects fertility in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.


Don’t breastfeed during this treatment because the drug may come through into your breast milk.

Treatment for other conditions 

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

Related links