Treating diarrhoea

Assessing diarrhoea

Your doctor will ask you some questions, and they might do some tests. This is to find out the cause of your diarrhoea. Finding the cause is important.

Severe constipation can cause diarrhoea so your doctor might need to examine your tummy (abdomen) or your back passage (rectal examination) to rule this out.

If the diarrhoea is a side effect of your cancer treatment, your medical team might change the dose or the schedule of your treatment until your diarrhoea is better. This may mean having a break from radiotherapy for a few days or lowering the dose of chemotherapy drugs.

Replacing fluid loss

You can lose a lot of fluid very quickly when you have diarrhoea. You could get dehydrated if you lose too much fluid. Aim to drink at least 8 to 10 cups each day. This can include tea, squash and milky drinks as well as soups, custard, jelly and ice lollies.

If you are dehydrated your body fluids, body salts, and sugars need to be replaced until your diarrhoea stops. 

Depending on how severe your diarrhoea is, this might mean:

• having fluids into a vein, through a drip in your arm - you might need to stay in hospital for this

• having drinks that contain salts and electrolytes to replace the lost fluid (if you are able to drink) 

The electrolyte drinks contain sodium, potassium, and sugar to help replace what you have lost. Your doctor or nurse can keep a check on your fluid and electrolyte levels by taking regular blood tests.

For severe diarrhoea you might be admitted to the hospital for fluid replacement. And you may also have antibiotics if you have a fever and signs of an infection.

Medicines to help with diarrhoea

Medicines that help to control diarrhoea are called anti diarrhoeals. There are several different types available from chemist shops without a prescription. But others need to be prescribed by your doctor.

Anti diarrhoea medicines

Loperamide is the main anti diarrheal medicine used to treat diarrhoea. Your doctor or pharmacist will tell you how much you should take and when to take it.

It works by slowing down the muscle movement in the gut. This means it takes longer for food to pass through your ​digestive system​ and more water is absorbed. This can help your poo to become firmer.

If diarrhoea is a known side effect of your cancer treatment, your doctor or nurse might give you anti diarrhoea medicines to take home with you after your treatment.

If your diarrhoea doesn't get better you should let your doctor or nurse know as soon as possible. They may be able to suggest a different treatment.

Speak to your specialist nurse about the best time to take these medicines and the possible side effects. 

Medicines to reduce tummy spasms and cramps

You might have painful tummy spasms or cramps when you have diarrhoea. If you do your doctor might recommend you take medicines called anti muscarinics. These help to reduce tummy spasms and cramping. An example of these medicines is hyoscine butylbromide (Buscopan).

Medicines to stop the body losing water

Medicines called somatostatin analogues lower the amount of fluid produced by the gut. They can help to stop the body losing water and body salts (electrolytes). Octreotide is one example of a somatostatin analogue drug.

These medicines also slow down the time it takes for food to move through the digestive system.

Side effects of anti diarrhoea medicines

Side effects of anti diarrhoea drugs are uncommon, but they can happen. Tell your doctor or nurse if any of these symptoms are severe or don't go away:

• a dry mouth

• dizziness

• drowsiness

• vomiting

• stomach pain, discomfort or swelling

• constipation

• tiredness (fatigue)

Rarely, some people have an allergic reaction to one of these medicines. Signs of an allergic reaction include a rash, shortness of breath, redness or swelling of the face, feeling hot, dizziness, or sudden wheezing. You need to go to a hospital straight away if you have any of these signs.

Read about the symptoms, causes and treatment of diarrhoea when you have cancer