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About sickness

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This page is about sickness due to cancer or its treatment. There is information about



Feeling sick is called nausea. It is an unpleasant feeling in the back of your throat and in your stomach that may or may not end up in you actually being sick. When you feel sick you may also

  • Feel dizzy or light headed
  • Make more saliva (spit) than usual
  • Have a faster heart rate
  • Have cold, clammy skin
  • Not want to eat or drink

Actually being sick is known as vomiting, or throwing up. Being sick means that your stomach muscles tighten up, forcing any food or liquid in your stomach up your throat and out of your mouth. You may or may not feel sick before this happens.

Retching means trying to be sick, but bringing nothing up. Your chest and stomach muscles contract as if you were going to be sick, but you aren't. You do not always feel sick before retching. It is sometimes also called heaving or dry heaves.


Why you feel sick

There are many different causes of sickness. But as far as your body is concerned, it is trying to get rid of something that shouldn't be there. A part of the brain called the vomiting centre controls being sick. The vomiting centre is in the brain stem.

You may be sick if the vomiting centre receives signals from

  • Another part of the brain called the chemo receptor trigger zone (CTZ)
  • Your stomach
  • Your inner ear - caused by motion, vertigo
  • Your senses – especially taste and smell
  • Your emotions – being frightened or anxious can make you sick

Chemotherapy drugs make your body release chemicals that signal between nerves. These are called neurotransmitters and include serotonin. These chemicals stimulate the CTZ and the vomiting centre. Anti sickness drugs can block these chemicals and stop the signals getting through. So they can stop you being sick.

We don't know quite so much about the control of feeling sick. It is probably controlled by the part of the nervous system that regulates things we don't have to think about, like breathing.

About half of the people treated for cancer will feel sick or be sick at some point during their illness. Nausea and vomiting are the treatment side effects that many people with cancer fear most. They can make everyday life very difficult to cope with. Feeling and being sick a lot can cause

If you are having problems with feeling or being sick, it is very important to tell your doctor or nurse. There are ways to control sickness. The treatment depends on what is causing your sickness.

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Updated: 21 January 2015