How cancer treatment can affect your mouth

Some cancer treatments can damage the cells that line your mouth or throat. Soreness and ulceration of the lining of the mouth or throat is called mucositis. It can be very painful. Mucositis can be caused by:

Any damage is usually temporary, and most side effects improve when treatment ends. But sometimes side effects can be permanent.

A common mouth infection called thrush (candidiasis) can make eating unpleasant and change how things taste. Thrush coats your tongue, the inside of your cheeks and the back of your throat. It can look red with spotty, pale patches. Your doctor can prescribe an anti-fungal medicine to help.

Your specialist nurse, doctor or speech and language therapist (SLT) will talk to you about mouth care during treatment. They may also look at your mouth. Tell them if your mouth becomes sore or if the soreness gets worse. They may be able to give you something to help.

Tips to keep your mouth healthy

The following tips may help keep your mouth healthy during and after cancer treatment.


  • Drink plenty of fluids, especially water. If fruit juices sting your mouth, try less acidic juices instead – for example, peach or pear nectar, or blackcurrant or rosehip syrup. You could try freezing them in an ice cube tray as sucking on the ice cubes can soothe your mouth.
  • Avoid fizzy drinks because these may sting your mouth.
  • Try milk or milk-based drinks, such as malted drinks, milkshakes and hot chocolate. These can be from cow’s milk, goat’s milk or a plant-based alternative such as soya, rice or oat milk.
  • Cold drinks may be soothing – try adding crushed ice to drinks.
  • Very hot or very cold drinks may irritate a sore mouth. Some people find drinks that are lukewarm or at room temperature more soothing.
  • Try drinking through a straw.


  • Avoid salty or spicy food.
  • Avoid rough-textured food like toast or raw vegetables.
  • Keep your food moist by adding sauces and gravies.
  • Cold foods may be soothing – try eating ice cream or soft, milk jellies.
  • You may find that taking painkillers before meals can help you swallow more easily.


Keeping your mouth as clean as possible during your treatment will help to prevent or reduce side effects in your mouth.

Using a mouthwash

Mouthwashes can be very soothing, but many of the ones available in chemists or shops may be too strong for you.

Salt water mouthwashes can help reduce soreness, if it is not too severe. To make the mouthwash, add 1 teaspoon of salt to cold or warm water. Rinse this around your mouth. Then spit it out and then rinse your mouth with cold or warm water.

Your doctor can prescribe an anaesthetic gel or mouthwash to help if needed.

Looking after your teeth or dentures

Many hospitals have their own mouth care guidelines for people having chemotherapy or radiotherapy, which include the best toothpaste to use. Your doctor or specialist nurse will be able to advise you.

You may be advised to see your dentist before you start treatment. They may recommend using a high-fluoride or non-foaming toothpaste to help reduce any soreness.

Use a soft toothbrush to clean your teeth gently. Avoid using toothpicks when cleaning your teeth. If you want to use dental floss, check with your doctor or specialist nurse first. If you have a low platelet count, flossing can make your gums bleed.

If you wear dentures, soak them in a denture-cleaning solution overnight. Leave them out for as long as you can during the day to prevent them rubbing against your gums.

If you are having radiotherapy to the jaw area, you may be advised to keep your dentures in as much as possible during the day. This helps to maintain the shape of your gums. But if your mouth is very sore, it may be more comfortable to leave your dentures out.

If your tongue is ‘coated’

This may make your food taste unpleasant and put you off eating. You can clean your tongue with a bicarbonate of soda solution. Dissolve 1 teaspoon of bicarbonate of soda (available from your chemist) in a pint (570mls) of warm water. Use a soft toothbrush or gauze dipped in the solution to clean your tongue.

If this does not help, talk to your doctor or specialist nurse, because you may have oral thrush and need medicine. If you are having radiotherapy for a head and neck cancer, brushing your tongue is not recommended. Your clinical nurse specialist can give you more advice.

Tips if you have a dry mouth

Radiotherapy to the head and neck area and treatment with some cancer drugs can damage the saliva glands. This may cause a dry mouth (xerostomia).

The following tips may be helpful for coping with a dry mouth during and after cancer treatment:

  • Taking sips of water can help keep your mouth moist. Keep a glass of water by your bed and carry water with you when you go out.
  • Try sucking ice cubes or lollies. You can make lollies by freezing fresh fruit juice in ice cube trays or in lolly containers with sticks.
  • Add moisture to make food easier to swallow, especially with dry and starchy foods like bread, biscuits, crackers and potatoes. For example, you could moisten foods with gravies, sauces, extra oil, salad dressings, yoghurt, mayonnaise or butter.
  • Chewing sugar-free gum can sometimes help you to produce more saliva.
  • Tell your doctor about your dry mouth. They can prescribe mouthwashes, lozenges, artificial saliva sprays, gels or tablets if needed.
  • Use a lip balm to protect your lips. But it is important not to use any on your lips during radiotherapy treatment. Speak to your clinical nurse specialist or radiotherapy team about this.
  • Try using an atomiser spray with cool water to keep your mouth moist. Keep this in your pocket when you go out.
  • Try to avoid alcohol (especially spirits), as these can irritate your mouth. This also includes mouthwashes that contain alcohol.
  • Do not smoke as this can irritate your mouth and make it feel dry.
  • Some drinks may irritate a dry mouth. Try to avoid caffeinated drinks or citrus drinks.

Tips for coping with changes to taste

You may find that food tastes different during treatment. This is usually temporary, but sometimes it can be permanent. You may no longer enjoy certain foods, or you may find that all food tastes the same. Food may taste very sweet or salty. Or you may have a metallic taste in your mouth or find that things taste like cardboard. You may lose your sense of taste, but it usually comes back.

The following tips may be helpful for coping with taste changes:

  • Try different foods to find out what tastes best to you. Keep trying different foods as your taste changes.
  • Eat foods that you enjoy and ignore those that do not appeal to you. But try them again after a few weeks, because your sense of taste may have changed.
  • Use seasonings, spices and herbs such as pepper, cumin or rosemary to flavour your cooking. But if your mouth is sore, you may find that some spices and seasonings make it worse.
  • Try eating bland foods such as bread, potatoes and crackers.
  • Try marinating meat.
  • Cold meats may taste better served with pickle or chutney.
  • Sharp-tasting foods can be refreshing and leave a pleasant taste in your mouth. These include fresh fruit, fruit juices and sugar-free sour or boiled sweets. Be careful if your mouth is sore as these may be painful to eat.
  • If you no longer like tea or coffee, try lemon tea, herbal teas or a cold drink such as lemonade.
  • Some people find that cold foods taste better than hot foods. If your sense of taste or smell changes, it may help to let your food cool before eating it.
  • Serve fish, chicken, red meat and egg dishes with sauces. You could add these sauces to vegetables too. But be careful if your mouth is sore as some sauces, such as curry or sweet and sour, may feel painful to eat.
  • If you notice a metallic taste in your mouth, try using re-usable plastic cutlery.
  • Brush your teeth before meals.

Tips for coping with difficulties chewing or swallowing

Some chemotherapy, targeted therapy and immunotherapy drugs, and radiotherapy for head or neck cancer can affect the cells in the lining of the throat. This can make it painful to chew or swallow. An infection in your mouth or throat, such as thrush, can also make chewing and swallowing uncomfortable.

Tell your doctor or dietitian if you have any difficulties chewing or swallowing. If you find that drinks make you cough, and you are feeling unwell, you should tell your doctor or nurse as soon as possible. A speech and language therapist (SLT) can advise you about problems with swallowing.

Here are some tips for coping with difficulties chewing or swallowing:

  • Taking painkillers 30 minutes before meals may help you chew and swallow more easily. Your doctor or nurse can suggest which painkillers might be best for you to take.
  • Choose foods that are easy to swallow, such as scrambled eggs, scrambled tofu or yoghurt.
  • Soften foods with sauces and gravy.
  • Finely chop meat and vegetables and cook them for a long time. For example, you could make a stew or casserole.
  • Cut the crusts off bread to make softer sandwiches. Some people find thin bread easier to swallow.
  • If you have a blender, you could liquidise cooked foods.
  • Some frozen-meal, home-delivery companies have a soft-food range on their menu.
  • There are several food supplements that you may find helpful, for example Complan® or Meritene® drinks. Your dietitian can provide nutritional advice and prescribe supplements if needed. You can buy these from your chemist or supermarket. Your doctor may give you a prescription for some of them. Always talk to your doctor or dietitian before taking supplements. They can explain which food supplements might be best for you.

About our information

  • References

    Below is a sample of the sources used in our mouth problems information. If you would like more information about the sources we use, please contact us at

    European Oral Care in Cancer Group – Oral Care Guidance and Support. 1st Edition. Available at: [Accessed 10.02.2020] 

    National Cancer Institute. Nutrition in Cancer Care. (PDQ) Updated 2019. [accessed March 2020] 

    The Royal College of Surgeons of England/The British Society for Disability and Oral Health. The oral management of oncology patients requiring radiotherapy, chemotherapy and/or bone marrow transplantation. Clinical Guidelines. 2018. 

    UK Oral Management in Cancer Care Group (UKOMiC), Oral Care guidance and support in cancer and palliative care (3rd edition), 2019. 

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 August 2020
Next review: 01 August 2023

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

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