Mouth care during and after cancer treatment

Some types of chemotherapy, immunotherapy and biological therapy drugs that are used to treat cancer can cause mouth problems. This information will help you to care for your mouth and offer advice on how to avoid some of the problems.

Common problems

Soreness and mouth ulcers (oral mucositis)

Sometimes the lining of your mouth becomes very sore. This is called oral mucositis, and can even cause mouth ulcers. It can happen about 5 to 10 days after you start treatment. It usually gradually clears up 3 to 4 weeks after your treatment ends. 

Bisphosphonates (bone-strengthening medicines) and hormone therapies do not usually cause a sore mouth.

Older people are at a greater risk of oral mucositis.

There is no specific treatment for oral mucositis once it has developed. Any treatment is aimed at reducing the severity and relieving the symptoms. 


Even if you follow our advice, you might still develop a viral or fungal infection in your mouth.

Contact us immediately if:

  • you have a temperature of 37.5°C
  • your mouth is really sore and it is affecting your ability to eat and drink
  • you notice a white coating on your tongue
  • you have large deep ulcers in your mouth

Taste changes

Some chemotherapy and biological therapy drugs can make food taste different, or may give you a metallic taste in your mouth. Your taste should gradually go back to normal when treatment is over, but it can take a few weeks.

Some tips that you can try are:

  • choosing foods that have strong flavours if all your food tastes the same
  • seasoning your food with spices or herbs
  • covering meat or fish in strong sauces like sweet and sour, or curry
  • trying lemon or green tea, if tea or coffee tastes strange
  • drinking sharp-tasting fizzy drinks like lemonade or ginger beer can be refreshing
  • trying cold food, some people find that it tastes better than hot food
  • trying wooden or plastic cutlery if things taste metallic

Dry lips

You might experience dry lips. Yellow paraffin (vaseline) or normal lip salve can be used to moisten your lips.

These products should not be used if you are having radiotherapy to your head or neck or if you are on oxygen. Discuss with your nurse or doctor about getting a water-soluble lubricant.

Dry mouth

Some cancer drugs can make your mouth dry. You could try:

  • sipping water regularly
  • keeping hydrated, try to drink at least 1.5 litres of fluid a day
  • sucking ice cubes to refresh your mouth
  • eating fresh or tinned fruits, but avoid acidic fruits (such as oranges, grapefruit) if your mouth is sore
  • sucking boiled sweets or chewing gum

If your mouth is very dry talk to your doctor or nurse about artificial saliva products.

Oral health

Good oral hygiene is very important during and after your cancer treatment. Most important is keeping your mouth clean, but here is some other advice.

  • Clean your mouth and teeth gently every morning, evening and after each meal.
  • Use a child’s or soft-bristled toothbrush if your mouth is sore.
  • Change your toothbrush every 3 months.
  • Use a toothpaste which contains fluoride.
  • If you have dentures remove and clean them every morning, evening, and after each meal.
  • Avoid mouthwashes that contain alcohol – check with your pharmacist if you are unsure.
  • Have regular dental checkups.

If you need any dental work during your cancer treatment, speak to your doctor or nurse about this.

Check your mouth daily for signs of redness, swelling, bleeding and white patches.

Contact us if you have any concerns.

General advice

Stopping smoking

Smoking can irritate the lining of your mouth and could make problems worse. Our Stop Smoking service can offer advice and help you to give up. Call 020 7188 0995 or you can call the National Quitline on 0800 169 0169.


Alcohol can irritate the lining of your mouth and could make problems worse. Consider reducing the amount of alcohol you have. We can offer advice and support with this, please speak to a doctor or nurse caring for you.

Drinking plenty of fluids

You should drink at least 1½ litres of fluids (water, tea, coffee, diluted fruit juice) a day.


Saltwater mouthwash: 1 teaspoon of salt to 900ml of cold or warm water, used at least 4 times a day. This will clean the mouth and remove debris. Make a fresh supply daily.

Soda water: Can be used as a mouthwash, 4 to 6 times a day and up to every 1.5 hours.

In addition to salt water, you can use benzydamine hydrochloride (Difflam™) to help reduce inflammation and numb the pain. This can be prescribed by your GP or cancer team, or purchased from your local pharmacy.

Use 10mls rinsed around the mouth and spat out, at least 4 times a day, and up to every 1.5 hours. It can be diluted in 10mls of water if this causes stinging.

Avoid mouthwashes that contain alcohol, for example, Corsodyl®.


We can refer you to the nutrition and dietetics team if needed.


You can take 2 x 500mg soluble paracetamol, up to 4 times a day. If you weigh less than 50kg (7stone 8lb) only take 1 x 500mg of paracetamol 4 times a day.

Your cancer team may provide other treatments and protective gels.

Useful information

Cancer Research UK has information about keeping your mouth as healthy as possible.

Resource number 4602/VER2
Date published March 2023
Review date March 2026

Contact us

Please contact us if you have any questions or concerns about your cancer treatment or side effects.

Chemotherapy Village

Phone: 020 7188 6452 Monday to Friday, 8.00am to 6.30pm

Acute Oncology Assessment Unit

Phone: 020 7188 3754 - 24 hour helpline

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

Is this health information page useful?