Diarrhoea During Cancer Treatment

Diarrhoea During Cancer Treatment

If your child has diarrhoea during their cancer treatment, there can be several causes.


Key points about diarrhoea during cancer treatment

  • diarrhoea means frequent, loose, watery poo
  • there can be several causes of diarrhoea in tamariki (children) having cancer treatment

What can cause diarrhoea during cancer treatment?

There can be several causes of diarrhoea in tamariki having cancer treatment.

The direct effect of chemotherapy

Chemotherapy can have a direct effect on the cells lining the gut - from the mouth right through to the bottom.


Viral infections can cause diarrhoea (infective gastroenteritis). Your child is more at risk of this if they have low infection-fighting ability (low immunity).

Food intolerances

These can be already existing food intolerances, intolerances related to temporary damage to the bowel caused by chemotherapy, or intolerances due to previous infections.

Eating infected food

See the section below on foods that your child should avoid. This lists the foods that are most likely to carry infection.

What food and fluids should I give my child with diarrhoea?

Diarrhoea may cause your child's body to lose fluid and can lead to dehydration. Give your child more fluid to replace fluids lost in the watery poo.

Water, diluted fruit juice or flat soft drinks are suitable.

Offer your child light meals that are smaller than usual. Offer these meals more frequently than normal.

Suitable meals include:

  • white bread
  • rice
  • pasta
  • mashed potato
  • pureed apple
  • fish
  • poultry
  • low fibre cereals such as cornflakes, Ricies and Coco-Pops

If your child has diarrhoea, they should temporarily avoid seeds, pips, skins and coarse stalks of fruit, vegetables and grain.

How can I keep food safe to eat for my child having cancer treatment?

Tamariki who are neutropenic are at risk of infection from eating infected food. Here are some tips for keeping food safe to eat:

  • always wash your hands before preparing food
  • use clean knives, chopping boards and benchtops when preparing food
  • store cooked food above raw food in the fridge and keep it covered
  • cook and reheat food until it is hot all the way through, especially when using a microwave oven
  • check the use-by date on prepared foods
  • wash raw fruit and vegetables under running water

Read more about hygiene and hand washing

Which foods should my child having cancer treatment avoid?

The following foods could be unsafe to eat - do not give them to your child with low infection-fighting ability (low immunity):

  • chilled or pre-cooked seafood products such as prawns, mussels, fish unless they are reheated so they are hot all the way through, and eaten while they are hot
  • pre-cooked meat products such as pate, pre-cooked chicken and ham
  • raw seafood and raw fish
  • raw eggs and dishes using uncooked eggs
  • shop-prepared salads and coleslaws
  • unpasteurised milk or milk products such as cheese made with unpasteurised milk - read the label for this information

Eating out can be risky because food in a restaurant may have been cooked earlier. Food cooked 'while you wait' is safe to eat. Do not ever eat chicken from a takeaway.

See more information about food safety for people with low immunity at the New Zealand Food Safety website

What should I do if my child has diarrhoea?

If your child has diarrhoea, tell your healthcare team.

Read more about infections during cancer treatment

Read more about childhood cancer


All the pages in the childhood cancer section of this website have been written by health professionals who work in the field of paediatric oncology. They have been reviewed by the members of the National Child Cancer Network (NZ). Medical information is authorised by the National Child Cancer Network Clinical Leader.

This page last reviewed 10 June 2021.

Call Healthline on 0800 611 116 any time of the day or night for free health advice when you need it