Treating diarrhoea

You can lose a lot of fluid very quickly when you have diarrhoea. So it is very important that you drink as much as you can. If you lose too much fluid and become dehydrated, your doctor will want to replace fluid and body salts until your diarrhoea stops.

Depending on how severe your diarrhoea is, this may mean having fluids into a vein, through a drip in your arm. If you are able to drink then your doctor may try to replace your fluid and body salts (electrolytes) by mouth. There are drinks that are specially made to rehydrate you, such as Dioralyte. You can buy these from the chemist, but always talk to the pharmacist first so they can check what other medicines you are taking and what your symptoms are. These drinks contain sodium, potassium and sugar to help replace what you have lost. They won’t stop the diarrhoea. And it is not clear if they are any better than water or soft drinks in helping you recover. Your doctor can keep a check on your fluid and electrolyte levels by taking regular blood tests.

Drugs that help to control diarrhoea are called ‘anti diarrhoeals’. There are several different types of these drugs available from chemist shops without a prescription. But others will need to be prescribed by your doctor.

Before you try any over the counter drugs to help with your diarrhoea it is very important that you talk to your doctor. They will need to find out what is causing your diarrhoea in order to decide on the best drug to help you.

The most common drugs doctors use to help with diarrhoea caused by cancer and treatment are

• Loperamide hydrochloride (Imodium)
• Co-Phenotrope (Lomotil)
• Codeine phosphate

Your doctor may suggest that you try one or more of these. They work by slowing down the time it takes for food to pass through your digestive tract. They may not get rid of your diarrhoea completely but at least they will help to slow it down.

There are other drugs that your doctor may suggest. As with many medical terms these drug groups tend to have complicated names. One group is called ‘anti muscarinic drugs’. These drugs help relieve tummy spasms and cramping. Hyoscine butylbromide (Buscopan) is one of the anti muscarinic drugs your doctor may prescribe.

Another group is called ‘somatostatin analogues’. These drugs lower the amount of fluid produced by the gut. This helps to stop the body losing water and body salts (electrolytes). They also slow down the time it takes for food to move through your digestive tract. Octreotide is a somatostatin analogue that your doctor may prescribe.

If diarrhoea is a known side effect of your cancer treatment, your doctor may give you anti-diarrhoeal drugs to take home with you after your treatment. If your diarrhoea does not get better with the anti diarrhoeal drugs your doctor has given you, you should let them know as soon as possible, so that they can suggest an alternative treatment.

To manage a side effect such as diarrhoea, it is not uncommon for doctors to change the dose or schedule of your cancer 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.

Side effects of anti diarrhoeal drugs are not common, but they can happen. Tell your doctor if any of these symptoms are severe or do not go away

• Dry mouth
• Dizziness
• Drowsiness
• Vomiting
• Stomach pain, discomfort or swelling
• Constipation
• Fatigue

It is rare, but possible, to have an allergic reaction to one of these drugs. If you come up in itchy lumps, like a nettle rash, or you have sudden wheezing, you could be having an allergic reaction and need to get to a hospital straight away.