There are many causes of fatigue and knowing about them may help you to cope with your fatigue a bit better.

Cancer treatments can often cause fatigue.

Following surgery, many people feel tired and need to take things easy for a while. This effect is usually temporary. However, some types of surgery may cause continuing problems with fatigue, for example if surgery to the stomach leads to problems with absorbing food.

Chemotherapy is the use of special anti-cancer (cytotoxic) drugs to destroy cancer cells. Radiotherapy treats cancer by using high-energy rays to destroy the cancer cells. Both can cause fatigue. This usually improves when treatment is over, but some people find it an ongoing problem.

Some people find they still feel tired and have low energy levels even a year after the treatment has ended. Others still feel tired two years or more after their cancer treatment. However, many people find their normal levels of energy will return within six months to a year of the treatment ending.

Hormonal therapies are treatments that can stop or slow the growth of cancer cells by either altering the levels of particular hormones in the body, or preventing the hormones from being taken up by cancer cells. These are often given for several years and some can cause fatigue.

Biological therapies use substances that occur naturally in the body to destroy cancer cells. Some can cause fatigue.

Anaemia is a common cause of fatigue in people with cancer. Anaemia is a shortage of haemoglobin in the blood. Haemoglobin is the chemical that carries oxygen around the body. It is found in red blood celIs. As red blood cells circulate in the body they carry oxygen to all the cells of the body to give energy.

If the number of red blood cells is low, they can’t carry much haemoglobin around the body, so less oxygen reaches the cells. Haemoglobin is measured in grammes per 100 millilitres (g/dl). The normal range of haemoglobin is 13.5 –17.5 g/dl for a man and 11.5 –15.5 g/dl for a woman. Research has shown that if the level of haemoglobin in the blood goes below 11 or 12, people feel much more tired, and their ability to enjoy life is lower. Doctors always keep a check on the levels of blood cells in people who have cancer, or are having cancer treatment.

People who have anaemia may also find that they:

• are breathless
• feel dizzy and light-headed
• have reduced sex drive (in both men and women)
• can’t get or maintain an erection
• have difficulty sleeping
• have aching in the muscle and joints
• have a worsening of angina (chest pain due to heart problems).

Chemotherapy treatment can also reduce the production of red blood cells and is a very common cause of anaemia in people with cancer.

Radiotherapy treatment for cancer can temporarily reduce the number of red blood cells produced by the bone marrow. This effect only occurs if the treatment is being given to an area of the body that contains bone marrow, such as the breastbone (sternum), the hip bones, or the long bones of the arms and legs.

Anaemia can also occur if a cancer has caused an ulcer (an area that won’t heal) somewhere in the body. Ulcers sometimes occur in the stomach or bowel lining and a small amount of blood can be continuously lost.

If you are having cancer treatment, you might consider writing down your haemoglobin levels in a diary. This may help you see how they affect your everyday life and your level of fatigue. It is important to share this information with your doctor, who may be able to give treatment for the anaemia. This can reduce the fatigue and help you to feel better.

Treatment for anaemia

This depends on the cause. The main treatment is a blood transfusion, which involves a drip (transfusion) of red blood cells given directly into the blood stream. It can quickly raise the number of circulating red blood cells.

As an alternative to a blood transfusion, some people are given a drug called erythropoietin. Erythropoietin is a protein that occurs naturally in the body. It stimulates the production of red blood cells by the bone marrow. Man-made versions of erythropoietin are available. They can be given to some people having chemotherapy to raise their level of red blood cells back to normal and reduce fatigue. You can discuss with your doctor whether erythropoietin would be suitable for your situation.

If you are feeling sick (nausea) you may not be getting enough energy from your food, as you are likely to be eating less. If you are actually being sick (vomiting) you are not absorbing the food, and this can also make you feel weak and tired. If you have nausea or vomiting, your doctor can prescribe anti-sickness drugs (anti-emetics) which should be taken regularly so that the sickness does not come back.

Loss of appetite due to treatment such as chemotherapy may mean that you have much less energy than usual.

Chemotherapy can cause changes in appetite and taste. If you find that some foods no longer appeal to you, try something different. Your doctor, nurse, or the hospital dietitian may be able to help.

It can help to get someone else to prepare food for you. Otherwise you may find that you use all your energy to cook the food and then feel too tired to eat it by the time it’s ready.

Small, frequent, simple meals are likely to be more tempting than large plates of rich food.

During difficult times, you could try ready-made, high-calorie drinks. These are available from any chemist and some are available on prescription. Unflavoured high-energy powders which add calories to food without adding bulk are also available on prescription.

Our section, eating well, has helpful tips on coping with eating difficulties caused by cancer or its treatment.

In some people, cancer can cause the cells in the body to release certain chemicals called cytokines. Cytokines affect the way the body makes use of food (metabolism). This may mean that the body is not able to produce as much energy from food or drink, so that a person does not put on weight (or loses weight) even if they are eating normally. This can lead to a condition known as cachexia which often causes fatigue.

Cancer treatments can sometimes reduce fatigue that is due to cytokine production. They do this by getting rid of the cancer cells, or reducing their number, which reduces the amount of cytokines produced in the body.

Many people with cancer don’t have pain, but it can cause fatigue in those who do. Effective painkillers can help to relieve pain and so reduce fatigue. Our section on controlling cancer pain discusses various ways of relieving pain.

Other symptoms due to cancer, such as breathlessness or fluid-retention, are also common causes of fatigue. If you have an infection or high temperature, your body needs more energy and this may lead to fatigue.

Treating the different symptoms that are causing or contributing to fatigue can often help to relieve it. It is important to let your doctor or nurse know about any symptoms that you have. You may find our section controlling the symptoms of cancer helpful. 

Anxiety, depression, stress and tension as well as a poor sleeping pattern can all contribute to fatigue. It is common for people to have anxiety or depression when they are first diagnosed with cancer, however these feelings generally get easier to manage as you come to terms with what has happened.

You may find it helpful to discuss how you feel with a close friend, your partner or other family member. Some people also find it helpful to talk to others at a local support group. Your GP or nurse can give you details of groups near to you, or you can ask the nurses on our helpline.

If your mood continues to be low most of the time, you may need help to cope with depression. You can discuss this with your GP, who can refer you to a counsellor or prescribe medicines if necessary.

Our section on the emotional effects of cancer discusses ways of dealing with the emotions that you may have.