top of page

Chemotherapy Side Effects - Diarrhoea

Diarrhoea is when you pass stools (poo) more frequently than normal, the stools are usually loose or watery in consistency.


Unfortunately, diarrhoea is a common side effect for people with cancer. It can be caused by the cancer itself or the cancer treatments. Some chemotherapy drugs irritate the lining of the digestive system which can cause diarrhoea. Also, cancer treatment can make you more susceptible to various infections, which can cause diarrhoea and the antibiotics used to treat some infections can also cause diarrhoea.


According to the Therapeutic Advances in Medical Oncology journal, diarrhoea is a side effect that as many as 50-80% of cancer patients experience, but people are still embarrassed to talk about their ‘poo'. So, if your loved one is suffering from diarrhoea, it’s important they discuss it with their care team. Persistent diarrhoea can lead to dehydration which can have serious consequences. Their doctor or cancer specialist will be able to help identify the cause of the diarrhoea and manage it. They may also prescribe anti-diarrhoea medication.


Many factors can affect the duration and severity of diarrhoea including the type and dose of chemotherapy but diarhhoea can happen soon after chemotherapy starts and may continue for up to 2 weeks after treatment has ended.

The following tips may help your loved one to cope with diarrhoea:


  • Drink plenty of clear fluids such as water, squash, apple juice, clear broth or frozen ice lollies to replace the fluid lost. Aim to drink at least a cup of water after each bout of diarrhoea - taking small, regular sips can help. Clear liquids keep the bowels from working too hard and help prevent irritation.

  • Avoid fizzy drinks as well as alcohol and coffee as they may irritate your digestive tract. Some people also recommend avoiding drinks that are too hot or too cold.

  • Many people also avoid milk and milk products as they can diarrhoea worse.

  • Eat small, frequent meals and eat meals slowly. Your body may find smaller amounts easier to digest.

  • Eat bland foods such as dry toast or bread, boiled potatoes, rice or soup.

  • Eat foods that contain potassium such as fruit juices, sports drinks, potatoes without the skin, apricots and bananas as potassium is often lost through diarrhoea.

  • Eat less fibre for example wholegrain foods, brown rice, nuts, seeds, bran, beans, legumes and raw fruit and vegetables until the diarrhoea improves.

  • Avoid foods that may irritate your digestive tract such as greasy, fatty foods, spicy foods or foods that contain acid, such as citrus fruit and juices as these can make the stomach and intestine churn and create more diarrhoea and discomfort.

  • Stay away from foods that are natural laxatives, such as prunes, prune juice, rhubarb and papaya. Sugarless chewing gum and sweets made with sugar alcohols (such as sorbitol or mannitol) can also act like a laxative.


Severe or long-term diarrhoea can make you feel very tired. The lower abdomen can become quite sore from intestinal cramps. Your loved one could try placing a warm hot water bottle wrapped in a towel or a wheat pack on the abdomen to relieve pain and discomfort.

Taking care of your skin


Frequent, watery stools can take a toll on the skin in your anal area so be sure to take extra care:

  • Don't wipe with dry toilet tissue, instead, try moist toilet wipes / sensitive skin baby wipes that slide along the skin and doesn’t pull at it. Make sure they don't contain alcohol, which is drying and can further aggravate skin.

  • If possible allow the area to air dry or gently blow dry using a cold setting.

  • Alternatively, gently pat the skin with a clean towel or tissue/toilet paper, rather than rubbing.

  • Applying a water-repellent ointment, such as those that contain petroleum jelly can help keep skin irritation to a minimum. Apply after you’ve cleaned and dried the skin.

  • Wearing loose-fitting clothing and cotton underwear can allow air to circulate, which can be soothing.


If the skin in this area does get irritated, sitting in a shallow bath of warm water (or a sitz bath that fits over a conventional toilet might be easier) for 15 minutes, several times a day may help reduce any discomfort and can help speed up the healing process by boosting the blood flow to the affected area. This also enables gentle cleansing if the area is too painful to touch. While warm water alone (make sure the temperature is warm enough to be therapeutic but not so hot that it makes the skin red) may be enough to promote healing, some people like to add epsom salts, non-iodised sea salt or witch hazel to help reduce itching and swelling. These home remedies are thought to inhibit bacterial growth and may help reduce the risk of infection, however do not add shower gel, bubble bath, or any type of scented soap as these can irritate and dry out damaged skin.

Disclaimer: The above advice has been collated from the cancer community – other people going through the same things as your loved one. But it doesn’t in anyway constitute medical advice. If you have any concerns, please ensure your loved one speaks to their medical care team.

All Guides

bottom of page