Some people having chemotherapy treatment find that their mouth gets very sore. This information gives some ideas about how you can look after your mouth before and during your chemotherapy treatment.

Chemotherapy drugs interfere with the way that the cells of the body divide and reproduce themselves. Both healthy cells and cancer cells are affected by chemotherapy drugs. Healthy cells can generally repair the damage caused by the chemotherapy, but cancer cells cannot and so they eventually die. When the healthy cells in the lining of the mouth are affected, this can lead to a number of side effects.

Soreness and ulceration of the mouth

Chemotherapy can cause the lining of the mouth to become very sore, and small ulcers may form. Soreness and ulceration of the lining of the mouth is known as mucositis and can be very painful.

Mouth infections

You are more likely to get an infection of the lining of your mouth if it becomes very sore and ulcerated, or if the number of white blood cells in your blood is reduced. Chemotherapy can temporarily reduce the number of white blood cells circulating in the blood. White blood cells play an important part in fighting infection, so for a while after having chemotherapy your resistance to infection may be reduced.

The most common mouth infection is a fungal infection called thrush (also known as candidiasis). Thrush usually appears as white patches, or a white coating, over the lining of the mouth and tongue. It is treated with anti-fungal medicines.

Dry mouth

Chemotherapy sometimes leads to a dry mouth.

Bleeding gums

Occasionally some bleeding or ulceration of the gums may develop.

Damage to the cells lining the mouth is usually temporary and most side effects will disappear once the treatment has finished and the number of white blood cells has returned to normal. The likelihood of developing a sore mouth varies from treatment to treatment and your doctors and nurses will be able to tell you how likely this will be with your particular type of chemotherapy.

You can do a lot to help to keep your mouth healthy. It is important to inspect your mouth daily for any signs of redness, swelling, sores, white patches or bleeding. Your nurse at the hospital can show you how to do this.

Helpful hints

• Clean your teeth or dentures gently every morning and evening, as well as after each meal.
• Use a soft-bristled or child's toothbrush. Toothbrush bristles can also be softened in hot water. An electric toothbrush can clean your teeth very effectively.
• Replace your toothbrush frequently to prevent problems with infection.
• If your toothpaste stings, or brushing your teeth makes you feel sick, try using a mouthwash (such as one teaspoon of bicarbonate of soda dissolved in a mug of warm water).
• If you have been sick, rinse out your mouth before cleaning your teeth as the acid in your vomit may damage your teeth.
• If your doctor prescribes a mouthwash for you, use it regularly as prescribed to prevent your mouth becoming sore.
• Sometimes, using a mouthwash over a long period of time may cause your teeth to discolour slightly. Let your doctor know if this happens to you. When you stop using the mouthwash, your teeth will return to their normal colour.
• You can gently use dental tape or floss daily, but check with your doctor that the level of platelets in your blood is high enough. (A low platelet count can cause bleeding in the mouth even with very gentle flossing). You should not use a toothpick at all.
• Keep your lips moist by using Vaseline®, or a flavoured lip balm if you prefer.
• Avoid neat spirits, tobacco, hot spices, garlic, onion, vinegar and salty food. These may irritate your mouth.
• Keep your mouth and food moist. Add gravies and sauces to your food to help swallowing.
• Some crunchy foods may damage your gums and should be avoided when your blood cell counts are low.
• Try to drink at least one and a half litres (three pints) of fluid a day – water, tea, weak coffee, and soft drinks such as apple juice.
• Avoid acidic drinks, such as orange and grapefruit juice. Warm herbal teas may be more soothing.
• Let your doctor know if you have mouth ulcers, as you may need medicines to help heal the ulcers and clear any infection.
• To keep your mouth fresh and moist, eat fresh pineapple chunks.

It is important to see a dentist a couple of weeks before you start your chemotherapy. Dentists can advise on any problems and can help you get your teeth and gums into the healthiest possible condition before your treatment begins.

If your mouth becomes dry during your chemotherapy treatment there will be less saliva to protect the teeth. Because of this your dentist may recommend that you use flouride toothpaste or use a flouride mouthwash during your chemotherapy to help protect your teeth.

If you need to have dental work done during your chemotherapy treatment, it is important to discuss this with your cancer specialist. There will be times during your chemotherapy when you will be at more risk of bleeding and infection and the timing of any dental work needs to be planned very carefully.

It can often be a good idea to see a dentist once you have finished your chemotherapy treatment. Your teeth are more prone to decay during treatment and it can be helpful to get a dental check-up.

Many hospitals have developed their own mouth care guidelines. You may have an oral (mouth) assessment at your hospital:

• to check your usual mouth care routine
• to identify the care needed to keep your mouth healthy.

An oral assessment guide can be useful for all patients who have mouth problems or who are at high risk of developing them. An oral assessment is helpful in deciding which treatment should be prescribed if your mouth becomes sore. Do not worry if you are not offered this at your hospital. It is important to tell your doctor and nurses that you have a sore mouth so that they can assess your mouth and recommend what needs to be done.

Mouthwashes Inflammation and ulceration can often be eased by the regular use of a mouthwash, two or three times a day. Mouthwashes containing chlorhexidine (Corsodyl®, Chlorohex® or Eludril®) can help to prevent infection. Benzydamine mouthwash (Difflam®) can be helpful as a local anaesthetic and can ease the discomfort caused by inflammation of the mouth lining.

Protective gels Using gels to form a protective coating can sometimes help to ease the pain and discomfort of mouth ulcers. The gels can either be applied directly to the sore areas in the mouth (Orabase®), or mixed with water and used as a mouthwash (Gelclair®).

Aspirin Sometimes soluble aspirin can be used as a mouthwash to relieve pain in the lining of the mouth. Some people having chemotherapy are advised not to swallow the aspirin, but it is usually fine to use as a mouthwash. It is helpful to check with your doctor before using aspirin.

Painkillers There are many pain-relieving medicines. If it is hard for you to swallow pills, you may be prescribed painkillers as a liquid.

It is important to take your painkillers as they are prescribed for you, even if this means getting up during the night to take them. This will help to keep a constant level of painkiller in your blood all the time, and this should make it more effective for you. Stronger painkillers, such as morphine or codeine, can make you constipated and you will usually be prescribed a laxative to take while you are taking them. Everyone is different and you may have to adjust the amount of laxatives you take to manage your constipation.

Occasionally, if the pain is severe and drinking is difficult, you may have to be admitted to hospital to be given fluids and painkillers by drip into a vein. This is more likely to occur in people who are having high-dose chemotherapy. Taking painkillers for mouth pain may be necessary for a while, but as the number of white blood cells in your blood increases and your immunity improves, the sores will heal and you will then be able to stop taking the painkillers.

Oral thrush If you have oral thrush (white patches in your mouth), this can be treated with a liquid anti-fungal medication such as nystatin. This is prescribed by your doctor and is used four times a day. Remember not to eat or drink for 30 minutes afterwards as the medicine may be washed off. Some anti-thrush medicines are given as tablets.

Antacid medicines Sucralfate is a drug that can help control mucositis during chemotherapy, by creating a protective layer over the sores to prevent the acid in saliva from coming into contact with them. The sucralfate does not numb your mouth but can provide comfort by coating the sores. It can cause side effects such as constipation, diarrhoea, a dry mouth and dizziness.

Some medicines, such as Maalox® or Asilone®, can neutralise the acid in the mouth and may help your mouth to feel less sore. Your doctor can prescribe these for you.

Mucilages Some hospitals prescribe mucilages to help to ease soreness. Mucilages are unmedicated jelly-like substances (lubricants). They are usually fruit-flavoured, and are kept in the fridge to be used as a mouth soother.

Ice chips With some chemotherapy drugs, sucking ice chips (or an ice-lolly) for 5–10 minutes before the drug is given and for half an hour afterwards can also help to prevent further mucositis and ulceration. Some people find that the cold can be very uncomfortable however. Ask your nurses and doctors if this might be helpful with the drugs you are going to have.

Generally, any soreness of your mouth will begin to improve when your white cell count returns to normal.

Many people have a loss of appetite and a loss of taste due to chemotherapy. If you notice these problems it may be helpful to discuss them with a dietitian at the hospital. They should be able to help you with any eating difficulties and suggest how to make food more palatable.

This section has been compiled using information from a number of reliable sources including:

• Oxford Textbook of Oncology (2nd edition). Souhami et al. Oxford University Press, 2002.
• The Chemotherapy Source Book (4th edition). Ed. Perry. Lippincott Williams and Wilkins, 2007.
• British National Formulary (54th edition). British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2007.

For further references, please see the general bibliography.