Sickness and vomiting explained

Feeling sick (nausea) is an unpleasant feeling in the back of your throat or in your stomach that may or may not lead to actually being sick. Being sick (vomiting) is when your stomach muscles tense up and force the contents of your stomach out through your mouth.

You may also try to be sick but bring nothing up (retching). Your chest and stomach muscles contract as if you are going to be sick, but you aren’t. You won’t always feel sick before retching.

When you feel sick you might also:

• look pale or greyish
• make more saliva (spit) than usual
• break into a cold sweat
• have a faster heart rate.

Usually, sickness is caused by your body trying to get rid of something that shouldn’t be there.

Feeling sick and vomiting is controlled by part of the brain called the vomiting centre. Your vomiting centre is triggered if it receives signals from:

• a part of the brain called the chemoreceptor trigger zone (CTZ)
• your stomach
• your inner ear, in response to body movements or dizziness (vertigo)
• your senses – especially taste and smell
• your emotions such as fear and anxiety.

Sickness and vomiting can be distressing and make it difficult to cope with everyday life. It can also cause:

• loss of interest in food (poor appetite)
• weight and muscle loss
• fluid changes in your body which can cause dehydration
• low mood
• feeling very tired (fatigue)and weak.

But there are  anti-sickness treatments and things you can do to help you manage sickness and lessen its effects.

Feeling and being sick is very common in people with cancer. It’s thought that between 40 and 70 out of 100 people with cancer (between 40 and 70%) feel sick or will be sick at some point. This can be either because of the cancer itself, or because of treatment.