Decorative image

Fatigue and cancer drugs

Read about which drugs cause the most tiredness (fatigue) and what can help you cope.

Many different types of drugs are used to treat cancer. Some can make you feel very tired and very low on energy. This is called fatigue.

Cancer fatigue is the most common side effect of cancer treatment. It affects between 7 and 8 out of every 10 people (70 to 80%). Some people taking cancer drugs have severe fatigue and say this is the most disruptive side effect of all.

Fatigue is often worse for people who:

  • have a combination of treatments such as radiotherapy, chemotherapy and biological therapy
  • have advanced cancer
  • are elderly

Even if a drug can cause fatigue, it may not affect you that way. Drugs affect people in different ways and it is not possible to tell in advance who will feel very tired. It depends on:

  • the drug or combination of drugs you are having
  • the dose
  • how you react to the drug
  • how you have reacted to drug treatment in the past

Symptoms of fatigue

Fatigue can cause any of the symptoms below, but they can also be due to other things. Let your doctor know if you have any of these signs.

  • Lack of energy and feeling that you just can’t be bothered to do much and wanting to stay in bed all day
  • Problems sleeping
  • Feeling anxious or depressed
  • Pain in your muscles that makes it hard to climb stairs or walk short distances
  • Being breathless after doing small tasks, such as having a shower or making your bed
  • Finding it hard to concentrate, even if watching TV or talking to a friend
  • Being unable to think clearly or make decisions easily
  • Loss of interest in doing things you usually enjoy
  • Loss of interest in sex
  • Negative feelings about yourself and other people

Effects of tiredness

Tiredness as a result of cancer treatment can be very frustrating. Some people say it is the most difficult side effect to deal with. It might not go away even if you rest.

Fatigue can affect you mentally, physically, emotionally and spiritually. Everyday life can be hard work. You might not feel like cooking, cleaning, having a bath or shopping.

With some types of cancer drugs the tiredness may go on for weeks or months after you finish treatment. It is then called chronic fatigue. Chronic means long lasting.

You and your relatives may underestimate how much fatigue can affect your daily life. Doctors can overlook it and you might feel that you have been left to cope alone. So it is important to tell your cancer specialist or nurse if you are very tired and have no energy.

Drugs that cause tiredness

Different drugs cause tiredness in different ways.

Nearly everyone who has chemotherapy has some tiredness. It can be due to the direct effect of chemotherapy on the body. But it may also be caused by anaemia because the chemotherapy can temporarily stop your bone marrow making red blood cells.

The number of red blood cells gradually starts to go down a few days after you have your chemotherapy drugs and may stay low until you finish your treatment.

You might have extreme tiredness due to anaemia during chemotherapy. When the chemotherapy ends, the blood cell levels gradually go back to normal over a few weeks.

Your normal energy levels should return between 6 months and a year after the end of chemotherapy. It can take even longer if you have intensive treatment, such as a bone marrow or stem cell transplant.

It is common to feel tired and lacking in energy when taking hormone therapy. The tiredness can be worse when you first start the treatment and gradually improve over a few weeks or months.

When you finish taking the treatment, the fatigue usually decreases over a few weeks.

Most people who have biological therapies feel tired during their treatment. For some the tiredness is severe. It might take a few months to a year to get back to normal energy levels after the treatment ends.

Some types of bisphosphonate treatment can cause tiredness but it is usually mild. You generally go back to normal energy levels over a few weeks once the treatment ends.

Some painkillers can make you feel sleepy or drowsy when you first have them. But your body gets used to the drugs over a few days and then the tiredness usually goes away.

What can help

More than half the cancer patients who have fatigue have never told their doctor or nurse about it. It can be hard to treat the actual cause of your fatigue. But if your doctors and nurses know about the tiredness they can try things to help you.

Feeling tired because of low red blood cells (anaemia)

You might have a blood transfusion if you are tired because you are anaemic. 

A drug called epoetin (EPO) can help reduce anaemia for some people. EPO is a manmade copy of a hormone called erythropoietin made by your kidneys. It stimulates the body to make more red blood cells and can reduce fatigue.

This drug is not suitable for everyone. The National Institute for Health and Care Excellence (NICE) recommends that only the following groups of cancer patients should have EPO:

  • people with anaemia related to their cancer treatment who cannot have blood transfusions
  • people with myeloma and kidney failure
  • women with ovarian cancer who have had chemotherapy with a platinum drug, such as carboplatin or cisplatin

Feeling tired because of low white blood cells

Your cancer treatment can also temporarily stop your bone marrow making white blood cells. This can make you less able to resist infection and can also make you feel tired.

Feeling tired because of sleeping badly, anxiety, or depression

Your fatigue may be made worse by sleeping badly, anxiety, or depression. A short course of sleeping tablets might help. It can help get you back into a pattern of sleeping properly.

Your doctor might suggest anti-depressants, if you are finding it hard to sleep because of depression. You need to take these for a few months to get the most out of them. Most anti-depressants take a few weeks to start to work. Talk to your doctor or nurse if you feel depressed.

Sleeping badly and fatigue can be difficult to cope with. You can call our Cancer Research UK nurses on 0808 800 4040 to talk it through. Lines are open Monday to Friday, 9am to 5pm.

Tips for you

  • Do some gentle exercise each day, this can give you more energy
  • Get support from other people, knowing others are there to help can be a real energy booster
  • Don’t push yourself too hard, rest when you begin to feel tired
  • Eat a well balanced diet to try to keep your energy levels up
  • Learn to manage fatigue, get help with shopping and housework and don’t try to do it all yourself
Last reviewed: 
07 Sep 2017
  • Cancer: Principles and Practice of Oncology 

    VT DeVita,TS Lawrence and SA Rosenberg

    Lippincott Williams and Wilkins, 2011

  • Drug therapy for the management of cancer-related fatigue

    O Minton and others

    Cochrane Database of Systematic Reviews, 2010

  • Electronic Medicines Compendium

    Accessed 2016

  • Epoetin alfa, epoetin beta and darbepoetin alfa for cancer treatment-induced anaemia

    National Institute of Health and Care Excellence, 2008

  • Exercise for the management of cancer-related fatigue in adults

    F Cramp and J Daniel

    Cochrane Database of Systematic Reviews, 2008

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in.

Information and help

Dangoor sponsorship

About Cancer generously supported by Dangoor Education since 2010.