Diet after anal cancer treatment

You might need to change what you eat after treatment for anal cancer. 

You'll find that your digestion takes time to settle down after anal cancer treatment. Some foods can upset the way your bowel and anus works. After treatment, high fibre foods, such as fruit and vegetables, may give you loose poo. You may need to go to the toilet much more often than normal.

Diet after surgery

Any changes needed in your diet will depend on the type of operation you've had.

If you've had surgery to remove your anus and rectum, you won't be able to eat immediately after your operation. But by the time you go home, you should be able to eat a regular diet. Your stools may be less solid if the surgeon removed part of your bowel. The bowel absorbs water as stool passes through it, so having less bowel means less water will be absorbed.

There's nothing you absolutely cannot eat. You may also find that what upsets your tummy at first is fine a couple of months later. So, if you do have difficulty with certain foods, avoid them for a while and try again later.

Some people are on a special diet for conditions such as diabetes. It is important to continue following this.


If you have a colostomy, you can follow the following tips in the days and weeks after surgery:

  • Eat small meals often.
  • Eat more protein such as chicken, fish, and dairy products
  • Chew food your food well. It can help to avoid indigestion.
  • If you don’t have much appetite, eat foods you enjoy.

Your stoma nurse will also give you advice on your diet when having a colostomy.

Foods that can cause wind

Some foods can cause wind, which is hard to control when you have had a colostomy. You might need to experiment to find out which foods upset your system. Foods that often cause problems with wind include:

  • high fibre fruits and vegetables
  • onions and cabbage
  • fizzy drinks and beer
  • rich or fatty foods

Seeing a dietitian

If you are having problems, your hospital can refer you to a dietitian, who can help you work out a diet that suits you. You might also find it useful to keep a food diary before you see them. A food diary is a record of:

  • what you eat
  • when you eat
  • any digestive problems you have, and when you have them

Keeping a food diary over a week may spot foods that are causing you problems. You can then cut them out of your diet.

Diet after radiotherapy

Radiotherapy for anal cancer often causes frequent bowel movements. This is because the rectum gets irritated and inflamed, and you might need to open your bowels urgently. The frequent bowel movements usually settle down a few weeks after the radiotherapy has finished, but it may continue for some people.

Your doctor can prescribe medicines to reduce inflammation.

If you have loose stools, it might help to stick to a diet low in insoluble fibre. Instead, follow a diet high in soluble fibre.

A diet low in insoluble fibre means: 

  • cutting out whole grain cereals and wholemeal bread
  • avoiding fibrous vegetables, fruit and fruit juice

A diet high in soluble fibre includes foods such as:

  • white rice
  • apples and pears without skin
  • apple sauce
  • oatmeal
  • smooth peanut butter
  • ripe bananas

Foods high in soluble fibre thicken the consistency of stools.

Over time, you can start eating the high fibre foods you cut out before. Some people also avoid alcohol as they find it makes their bowel symptoms worse.

Diet after chemotherapy

Chemotherapy for anal cancer can give you diarrhoea and might make you feel sick. These side effects will disappear after your treatment is over. Over time, you will be able to get back to a regular diet.

You are likely to have a combination of chemotherapy with radiotherapy. This can make the side effects harder to cope with. Speak to your specialist nurse or doctor if this happens. They can suggest ways to reduce any unpleasant side effects.

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