Cancer as a cause of sickness | Cancer Research UK
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Cancer as a cause of sickness

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This page tells you about how cancer can cause sickness. There is information about


Chemicals made by the cancer

Some types of cancer can make chemicals in your body that affect the way your cells work. Cancers that stop your kidneys and liver working properly can make you feel or be sick.


Raised pressure from a brain tumour

If you have a brain tumour or a cancer that has spread to your brain (secondary brain tumour), it may cause increased pressure in the head. As the skull is made of bone, there is a fixed amount of space for the brain. The growing tumour increases the pressure inside this fixed space. You may hear this called raised intracranial pressure (raised ICP). The increase in pressure causes

  • Sickness
  • Headache
  • Drowsiness

Tumours blocking the digestive system

If your cancer is growing in your digestive system (for example, in your bowel or stomach), it can stop food from passing through. This is a common cause of feeling sick.


Sickness in advanced cancer

Some people in the advanced stages of cancer may feel or be sick a lot. This type of sickness is very different to that of people having chemotherapy or radiotherapy. It can severely affect your day to day life and make you very tired and depressed.

People with advanced cancer can feel and be sick for different reasons. These include

As with any symptom, the best thing to do is try to treat the cause. For example, if constipation is causing the sickness, then treating the constipation should control the sickness. Sometimes it isn't possible to treat the cause. In this case, anti sickness drugs are the next best choice.

Too much calcium in the blood

Sometimes cancer can make calcium leak into your bloodstream. This can happen if cancer cells in the bones start to break down the bone cells. But it can also happen because the cancer has upset the body's normal system for controlling calcium levels. Calcium is important for keeping your bones strong and your nerves working properly.

Normally, the body regulates calcium levels very closely. Too much calcium in the blood is called hypercalcaemia. It makes you feel very thirsty, sick, constipated and drowsy. You may also pass a lot of urine as your body tries to get rid of the extra calcium. Confusion and muddled thinking can also be a sign. If hypercalcaemia is not treated, it can make you drowsy and difficult to wake. If it is left untreated, you could eventually become unconscious. There is more about hypercalcaemia in this section.

Slow gut

The digestive system can sometimes slow down due to

  • Cancer in the abdomen pressing on the muscles of the bowel
  • Cancer pressing on the nerves that supply the bowel (the coeliac plexus)

As food does not pass through the bowel as quickly as normal this can make you feel sick. Doctors call this sluggish gut.

Emotional effects

Being very nervous or worried about cancer and its treatment can make you feel sick or even be sick. Sometimes talking about your situation can help to reduce your worry and so reduce sickness.

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Updated: 21 January 2015