Erythropoietin (EPO)

Erythropoietin is a type of protein called a growth factor. It is used to treat a low number of red blood cells (anaemia) due to cancer or its treatment.

What is erythropoietin?

Erythropoietin (EPO) is a treatment for anaemia. This means having too few red cells in the blood. Anaemia is also sometimes called having low haemoglobin (low 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 by chemotherapy

If you have anaemia and cancer, doctors usually treat the anaemia with a blood transfusion. But they may use erythropoietin if:

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

People who have a bone marrow condition called myelodysplasia are also sometimes given erythropoietin. This is to increase their red blood cell numbers.

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 make red blood cells.

Erythropoietin can also be made in a laboratory, as a treatment for people with anaemia. There are different types of erythropoietin treatments. They include:

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

These treatments are often called 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 teach you, or a person caring for you, how to inject it. If you or a carer cannot give the injections, a district or practice nurse may do it for you.

How often you have erythropoietin depends on the type of erythropoietin used. Your doctor will explain how often you will need the injections. 

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.

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

If blood tests show no increase in red cells or haemoglobin level after 2 treatment cycles, you usually stop treatment. If blood tests show the treatment is working, you usually continue having injections until 1 month after you finish your course of chemotherapy. Or you may continue until you are no longer anaemic.

About side effects

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

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 them all. 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.

If you have chemotherapy with erythropoietin, some side effects may be worse. We have more information about chemotherapy.

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 has finished, 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) for more detailed information.

Common side effects

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 or being sick

You may feel sick during treatment with erythropoietin. Your doctor will give you anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as your nurse or pharmacist tells you. It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluids and eat small amounts often. If you continue to feel sick, or if you vomit more than once in 24 hours, contact the hospital as soon as possible. They will give you advice and may change the anti-sickness drug to one that works 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.

Blood clot risk

Cancer can increase the risk of a blood clot. Erythropoietin may increase this risk further.

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, so it is important to treat it as soon as possible. It is treated with drugs that thin the blood. Your doctor or nurse can give you more information.


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

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 straight away if you: 

  • have a severe headache
  • feel drowsy or confused
  • have problems with your eyesight
  • have fits
  • start being sick (vomiting)

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

Muscle, joint or bone pain

Eprex® may cause pain in muscles, bones or joints. If this happens, tell your doctor so they can give you painkillers. Tell them if the pain does not get better. Having warm baths and taking regular rests may help.

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.


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 other people, notice 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 where 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, or have a skin rash and feel unwell, stop taking erythropoietin. Contact a doctor straight away.

Other information

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 cause a cancer to grow. But 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 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 doctor or specialist nurse.

Storing erythropoietin

Follow any storage instructions given by your pharmacist. 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 come up to room temperature.

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

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.


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, or for some time after treatment finishes. This is because the drugs could be passed to the baby through breast milk.

Your doctor or nurse can give you more information.

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.