Diarrhea related to cancer treatment

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Diarrhea during cancer treatment may be caused by many things. Find out what can cause diarrhea and ways you can manage it.

Key points

  • Diarrhea can be caused by chemotherapy and radiation, medications and supplements, or gut infections.
  • Tell your health-care team if you are experiencing frequent, severe diarrhea, as this can cause dehydration.
  • Depending on the cause of diarrhea, it can be managed through diet or medications.
  • Drink lots of fluids to help keep your body hydrated.

What is diarrhea?

Diarrhea is when you have frequent, really soft or watery bowel movements (poos). It can be caused by many things, such as:

  • chemotherapy and radiation
  • antibiotics
  • some supplements such as magnesium
  • bone marrow transplant drugs
  • gut infections

Some causes of diarrhea are easy to treat, so your health-care team will want to know if you need any help with this.

It’s also important to tell your health-care team if you’re experiencing severe, frequent diarrhea. This can cause dehydration to happen quickly, which can be very dangerous.

How can I manage diarrhea?

One thing you can try is to change your diet. Eating smaller meals throughout the day, instead of three larger meals, may be easier for you to digest.

Your stomach may not be able to handle as much fibre as it used to. Eat foods that are low in fibre such as bananas, rice, apple sauce, eggs and dry toast. These are easier for your digestive system to tolerate. You can also keep fibre content low by cooking veggies and fruits, instead of eating them raw. If you find that dairy upsets your stomach, avoid it or try lactose-free products instead.

If your diarrhea is caused by chemotherapy or radiation, changes to diet may not help much, unfortunately. But your doctor may be able to prescribe medications that can help manage diarrhea.

No matter what causes your diarrhea, it’s important to keep drinking lots of fluids to help your body keep up with all the water it’s losing. Some people find that sports drinks or electrolyte replacement drinks help a lot when they have diarrhea, but try not to have too many of these as the sugars may increase diarrhea.

The lifestyle section has more tips on how to eat properly when you feel sick.

You might also find it useful to follow the tips to reduce nausea​. Many of them can also be used to help with diarrhea.

Last updated: September 3rd 2019