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Your mouth and cancer drugs

Find out how cancer drugs can affect your mouth, including mouth ulcers and taste changes.

Many different types of drugs are used to treat cancer. Some drugs can affect the lining of your mouth and make it sore. Other drugs may temporarily change your sense of taste.

Even if a drug can cause these effects, it may not affect you that way. Drugs affect people in different ways and it is not possible to tell in advance who will have side effects. It depends on:

  • the drug or combination of drugs you are having
  • the dose
  • how you react to the drug
  • how you have reacted to drug treatment in the past

Soreness and mouth ulcers


Some types of chemotherapy and biological therapy drugs can cause changes in the lining of your mouth and make it very sore. Some of these drugs can even cause mouth ulcers.

Inflammation of the inside of your mouth is called mucositis. 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 and hormone therapies do not usually cause a sore mouth.


Sometimes mouth ulcers can get infected. Your doctor or nurse can give you treatment for this.

Your nurse might give you mouthwashes to help prevent infection, if you are having drugs that are known to cause mouth ulcers. You have to use these regularly to get the most protection.

Tell your doctor or nurse straight away if your mouth is really sore. They can help to reduce the discomfort. You might need strong painkillers such as morphine or morphine based painkillers to help control mouth pain and be able to eat and drink.

Your doctor can prescribe medicines to help prevent mouth soreness if you're having high dose chemotherapy and radiotherapy before a stem cell transplant.

Tips for keeping your teeth clean

  • Clean your mouth and teeth gently every morning, evening and after each meal.
  • Use a child’s, or soft bristled, toothbrush.
  • Remove and clean dentures every morning, evening, and after each meal.
  • If toothpaste stings, or brushing your teeth makes you feel sick, try a bicarbonate of soda mouthwash instead (one teaspoonful dissolved in a mug of warm water).
  • Half a teaspoon of salt dissolved in warm water and then gargled can be soothing.
  • Avoid mouthwashes that contain alcohol - check with your pharmacist if you are unsure.
  • Use dental floss daily but be very gentle so that you don't harm your gums - don't floss if you have very low platelets.
  • Use lip balm to keep your lips moist.

Tips for eating with a sore mouth

  • Avoid neat spirits, tobacco, hot spices, garlic, onion, vinegar and salty food.
  • Moisten meals with gravies and sauces to make swallowing easier.
  • Try to drink at least one and a half litres (3 pints) of fluid a day – have tea or coffee, fruit and vegetable juices, soft drinks or water.
  • Tell your doctor if you have mouth ulcers.
  • Avoid acidic fruits such as oranges, grapefruit, or lemons.
  • Chew gum to help you to produce more saliva to keep your mouth moist.

Taste changes

Some chemotherapy and biological therapy drugs can make food taste strange or may give you a metallic taste in your mouth. Food might taste:

  • salty
  • bitter
  • metallic

Your taste should gradually go back to normal when treatment is over, but it can take a few weeks.

Tips for taste changes

  • Avoid foods that taste strange to you, but try them every few weeks as your taste may have gone back to normal.
  • Choose foods that have strong flavours, such as herbs, spices, marinades and sauces, if all your food tastes the same.
  • Season your food with spices or herbs, such as rosemary, basil and mint.
  • Garnish cold meat or cheese with pickle or chutney.
  • Marinate meat in fruit juice or wine.
  • Cover meat or fish in strong sauces like sweet and sour or curry.
  • Try lemon or green tea, if tea or coffee tastes strange.
  • Sharp tasting fizzy drinks like lemonade or ginger beer are refreshing.
  • Some people find that cold foods taste better than hot foods.

A dry mouth

Some cancer drugs can make your mouth dry. This can happen with chemotherapy drugs, biological therapy drugs, painkillers or hormone therapies.


  • Keep a drink available that you can sip.
  • Try to drink at least 3 pints (one and a half litres) of fluid a day.
  • Choose meals that are moist.
  • Use gravies and sauces to make swallowing easier.
  • Milk, water, fruit or vegetable juices are the best drinks to choose, but any fluid is better than nothing.
  • Suck ice chips to refresh your mouth.
  • Eating fresh or tinned pineapple can keep your mouth fresh and moist, but avoid acidic fruits (such as oranges, grapefruit) if your mouth is sore.
  • If you want to drink citrus juices, dilute them with water so they are not as acidic.
  • If your mouth is very dry talk to your doctor or nurse about artificial saliva products – there are tablets, mouthwashes, gum, pastilles, and toothpastes.

More information

There are many ways your team can help you with a sore mouth and other mouth problems.

Information and help

Dangoor sponsorship

About Cancer generously supported by Dangoor Education since 2010.