How erythropoietin works

Erythropoietin is a type of protein called a growth factor. The body makes it naturally. It works by stimulating the bone marrow (where blood cells are made) to produce red blood cells.

Erythropoietin can also be made in a laboratory, as a treatment for people with too few red blood cells (anaemia).

There are different types of erythropoietin treatments that include:

  • epoetin alfa (for example Eprex®), epoetin beta (for example, NeoRecormon®), and epoetin zeta (for example, Retacrit®)
  • darbepoetin alfa (Aranesp®)

People often call these treatments EPO.

How erythropoietin is given

You have erythropoietin as an injection under the skin (subcutaneously). It is usually given into the thigh or tummy.

A nurse can show you, or a family member or carer, how to do this. Or a district or practice nurse may do it for you.

Your doctor may give you iron tablets, or injections of iron, before or during your treatment.

Your body uses iron to make red blood cells. Your doctor can tell you if this will be helpful for you.

Erythropoietin can be given:

  • 3 times a week
  • once a week
  • every 3 weeks.

How often you have it depends on the type of erythropoietin used. Some types work for longer in your body than others.

You will have regular blood tests to check how your red blood cell and haemoglobin levels are responding to treatment. Your doctor may change the dose of erythropoietin, depending on these results.

If blood tests show no improvement in red cells or haemoglobin levels after 2 treatment cycles, you will stop treatment.

If blood tests show the treatment is working, you usually continue having injections until 1 month after finishing your course of chemotherapy.

Or you may continue until you are no longer anaemic.

Possible side effects of erythropoietin

When you have erythropoietin injections, the amount of erythropoietin in your body becomes much higher than normal. This may cause side effects, but these are usually mild or moderate.

We have included the most common side effects of erythropoietin. We have not included all the less common and rarer side effects. You may get some of the side effects we mention, but you will not get them all. Your nurse will give you advice about managing side effects.

If you have chemotherapy with erythropoietin, some side effects may be worse. You may also have side effects not listed here. We have more information about chemotherapy.

Your doctor can prescribe drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist has explained. This will help the drugs work as well as possible for you.

After your treatment is over, side effects will start to improve.

Always tell your cancer doctor or specialist nurse about the side effects you have.

Serious and life-threatening side effects

Sometimes, cancer drugs can result in very serious side effects. Rarely, these may be life-threatening. Your cancer doctor and 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.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. You can call them if you feel unwell or need advice any time of day or night.

Save these numbers in your phone or keep them somewhere safe.

Allergic reaction

Rarely, some people have an allergic reaction to erythropoietin. Contact the hospital straight away on the number you have been given if you develop any of the following:

  • red, warm and itchy bumps on the skin (like nettle rash)
  • swelling of the lips, tongue or throat
  • breathlessness, wheezing, a cough or sudden difficulty breathing
  • tight chest or chest pain.

Feeling sick

Your doctor can give you anti-sickness 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.


If you have diarrhoea,tit can usually be controlled with medicines. Follow any advice you have been given about taking anti-diarrhoea drugs. Tell your doctor if the diarrhoea is severe or if continues after taking the anti-diarrhoea drugs. It is important to drink at least 2 litres (3½ pints) of fluids each day.This stops you getting too dehydrated. It can help to avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods.

Flu-like symptoms

Some people have flu-like symptoms, such as: 

  • feeling sick
  • joint pains
  • weakness
  • dizziness
  • tiredness. 

You are more likely to have these symptoms at the start of your treatment. Usually, they last for a few days. Your doctor may advise you to take paracetamol to help with these symptoms.

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.

Muscle, joint or bone pain

One type of erythropoietin, called Eprex®, may cause pain in muscles, bones or joints. Tell your doctor if this happens, so they can prescribe painkillers. Let them know if the pain does not get better.

High blood pressure

Erythropoietin may cause high blood pressure. Tell your doctor or nurse if you have ever had any problems with your blood pressure. You should also tell them if you take any medication for high blood pressure. Your nurse will check your blood pressure regularly during your treatment. 

Contact your doctor or seek medical advice straight away if you have: 

  • a severe headache
  • drowsiness or confusion
  • problems with your eyesight
  • fits
  • start being sick (vomiting)

These are signs that your blood pressure may be very high. 


Erythropoietin can increase the risk of having a stroke.

Signs of a stroke include:

  • weakness or numbness in one side of your body
  • slurred speech or drooping of your face, mouth or eye.

If you, or someone you know, notices you have any of these symptoms, get medical advice straight away.

Swollen hands or feet

Your ankles, feet or fingers may swell because of fluid building up. Tell your doctor or nurse if this happens.

If your feet and ankles swell, it can help to put your legs up on a foot stool or cushion.

Skin irritation at the injection site

Your skin may become red or tender in the area the injection is given.

Injecting into a different area of skin each time can help reduce skin irritation.

Skin rash

You may develop a skin rash, which may be itchy and red. Tell your doctor if you notice this.

They can give you advice and may prescribe creams or medicines to help.

Rarely, people develop more serious skin reactions.

These can include:

  • a target-like rash (round red patches with an inner circle or blister inside)
  • blisters on the skin
  • ulcers in the mouth or in other parts of the body
  • sore, red eyes.

If you develop any of these symptoms, or have a skin rash and feel unwell, stop taking erythropoietin and contact a doctor straight away.

Other information about erythropoietin

It is important to tell your doctor straight away if you feel unwell or have any severe side effects, even if they are not mentioned above.

Many clinical trials have looked at the benefits of using erythropoietin to treat people with cancer. Some of these trials raised concerns that erythropoietin may, in some situations, cause a cancer to grow. However, many of these trials used erythropoietin in ways that are not now recommended for people with cancer. For example, it was used in people not having chemotherapy, or to raise a person’s haemoglobin (Hb) level above 120g/l.

The results of these trials were reviewed by the drug safety authorities. They recommend that some people with cancer will benefit from having erythropoietin. But before prescribing it, the doctor should always consider the benefits and risks in each person’s situation.

If you are worried or have any questions about this, talk to your cancer doctor or specialist nurse.

Storing erythropoietin

Follow any storage instructions that your pharmacist gives you.

Erythropoietin should be stored in the fridge in its original packaging.

Take the injection out of the fridge 30 minutes before you use it, so it can get up to room temperature.

Check with your pharmacist if you have any questions or concerns about storing this drug.

Other medicines

Some medicines can interact with erythropoietin. Tell your doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies.

This includes medicines and supplements you can buy in a shop or chemist.


Your doctor will advise you not to become pregnant or make someone pregnant while having erythropoietin. This is because it may harm the developing baby.

It is important to use effective contraception while having this drug, and for at least a few months afterwards.

You can discuss this with your doctor or nurse.


Women are advised not to breastfeed during treatment and for a few months afterwards.

This is because the drugs could be passed to the baby through breast milk.

Going into hospital or having dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having erythropoietin 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 treatment with erythropoietin.

When erythropoietin may be used

Erythropoietin is a treatment for anaemia. Anaemia means the number of red blood cells in your blood is low. It is also sometimes called having a low haemoglobin (Hb).

Red blood cells carry oxygen round the body. If you have too few, you may feel very tired, lack energy and get cold or breathless easily.

Many people with cancer develop anaemia at some point during their illness. This can be caused by the cancer, or chemotherapy.

For people with cancer, doctors usually treat anaemia with a blood transfusion. But they may use erythropoietin if you are having chemotherapy where:

  • you are likely to need blood transfusions often
  • blood transfusions are not suitable for you, because of other health conditions.

People who have a bone marrow condition called myelodysplasia also sometimes have erythropoietin. This is to increase the number of red blood cells.

If you are having erythropoietin for anaemia caused by chemotherapy or myelodysplasia, doctors will try to keep your haemoglobin level between 100g/l and 120g/l.