Treating mouth problems | Cancer Research UK
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Looking after your mouth

Preventing mouth problems is better than trying to treat them once they have already happened. You can help prevent mouth problems by keeping your mouth clean and moist. This may not keep mouth problems away altogether, but will make you less likely to get an infection on top of mouth ulcers or a sore mouth. We have information about how to take care of your mouth.

If you do develop any mouth problems, tell your doctor or nurse about them straight away.


Treating mouth ulcers

Mouth ulcers are most likely to develop about 5 to 10 days after chemotherapy starts. They start a bit later with radiotherapy to the mouth. They usually go away soon after your treatment finishes. Ulcers caused by biological therapy may occur several weeks or months after the first dose.

Sometimes mouth ulcers get infected. Infection is more serious when you are having treatment for cancer, and your doctor will need to treat the infection quickly. If you are having a cancer drug that tends to cause mouth ulcers, your doctor will give you mouthwashes to prevent infection.

You may get an infection in your mouth called thrush. You can usually treat this with anti fungal mouth drops, pastilles or a gel. You may also have a course of anti fungal tablets. But if it becomes very bad, you may need to have anti fungal treatment through a drip into a vein in your arm.

Sometimes mouth ulcers can get so bad that your doctor may decide to lower your dose of the cancer drug or stop treatment altogether until the ulcers clear up. This can be very distressing as you probably just want to get the treatment over with as soon as possible. But it is very important that your mouth recovers before you go on with treatment. Discuss any worries you have with your doctor and nurses. They understand that this set back may be difficult for you to deal with.


Treating a sore, dry mouth

Your mouth may get sore during radiotherapy treatment to your head or neck or during a course of cancer drugs. If your mouth or gums are really sore, tell your doctor straight away. You are not making a fuss and most doctors will be happy to give you strong painkillers for this. If the pain in your mouth is very bad, you may need a morphine drip for a short time while you recover.

Radiotherapy to the head and neck can affect the glands that keep your mouth moist by making spit (saliva). You may make less saliva than usual, or none at all. This can make it uncomfortable to chew or swallow. Speaking can also feel strange if your mouth is very dry. A dry mouth also increases the risk of infection as saliva is also very important in keeping your mouth healthy and preventing the build up of micro organisms.

It can take a long time (6 months or more) for saliva production to go back to normal after radiotherapy treatment. If you've had radiotherapy directly to your salivary glands, they may never completely recover. 

If you are making some saliva, drugs to stimulate your salivary glands may help. These include pilocarpine and bethanechol. The drugs have side effects and may cause sweating, blurred vision, or sickness. It may take up to 3 months for pilocarpine to work. Other possible saliva stimulants include sugar free chewing gum or mints, or sucking boiled sweets. 

If you are making no saliva at all, ask your doctor or specialist nurse about artificial saliva. This comes as

  • A lozenge that you suck
  • A spray
  • A mouth gel

A Cochrane review looked at how well topical treatments work for people with a dry mouth. A topical treatment is applied directly to the inside of the mouth, for example sprays, lozenges, mouth washes or gels. The reviewers found that there is no strong evidence that any of these topical treatments help people with a dry mouth. You can read this review on the management of a dry mouth in the Cochrane library. It was written for researchers and specialists so is not in plain English.

It is still worth asking your doctor or nurse about artificial saliva as some people find it helps. There are different types of artificial saliva. Some doctors think that the best to use is based on mucin. Mucin is a natural substance found in mucus and saliva. So it is similar to natural saliva. Mucin spray saliva contains traces of pork products, though, which may concern you if eating pork is a moral or religious issue for you. The Cochrane review did not find any strong evidence to say that mucin spray saliva worked better than a placebo. So more research is needed

You may need to try more than one type of artificial saliva. Different products suit different people. Your doctor will tell you how often you need to use it - usually before meals. Some preparations of artificial saliva can make your mouth feel sticky. As well as having artificial saliva, it is also important to carry out regular mouth care and sip cool drinks to help with a dry mouth.

Some people find that acupuncture helps them. A Cochrane review found that the research looking at acupuncture for people with a dry mouth is of poor quality. This may be because the studies have been too small to show a difference in a dry mouth. And it may be that both the people having real acupuncture and the people having the placebo acupuncture found it helped. There wasn't a big difference between the 2 groups. So we need more research before we know exactly how much it can help. You can read the review on non drug treatments for dry mouth symptoms in the Cochrane library. It was written for researchers and specialists so is not in plain English.

You can read more about research into mouth problems in this section on our website.


Taste changes

Your sense of taste may change as soon as you start treatment or some time afterwards. With radiotherapy, it usually takes a while before you notice taste changes. With some cancer drugs, you may notice it as soon as you have your injection or drip.

If necessary, you can talk to a dietitian for advice on dealing with taste changes. Ask your doctor or nurse.

We have information about coping with taste changes.


Tooth decay

Having radiotherapy to your mouth makes you more likely to get tooth decay. You will need to go for check ups at the dentist more often than usual during and after your course of treatment. Having fluoride treatment before your radiotherapy begins may help to protect your teeth. The fluoride treatment may be a mouthwash or gel you use every day. If some of your teeth are unhealthy, your dentist may need to remove them before you start radiotherapy.

Bisphosphonates, such as zoledronic acid, are drugs that help prevent or control bone thinning. Doctors use them to help treat some types of cancer that cause bone damage. If you are due to have a bisphosphonate, your doctor will advise you to have a dental check up and any necessary dental work before you start. This is due to the link between bisphosphonates and damage to the jaw bone (osteonecrosis). This is a rare side effect that may happen if you take bisphosphonates for longer than a year.

We have information about bisphosphonates and jaw problems.

Remember that if you have been having cancer treatment, or are going to have it, tell your dentist before you have any dental work done. You should continue to have regular check ups with your dentist once your treatment has finished.


Denture problems

Your cancer treatment may make your mouth sore and dry, and this can make it difficult to keep your dentures in. See your dentist if you have any problems. Clean your dentures at least twice a day. If they are causing a lot of trouble you may be tempted to leave them out for long periods. But this is not usually a good idea as your gums can change shape if you don't wear your teeth. Your dentures then may not fit and will be uncomfortable to wear after your treatment ends. Ask your doctor or dentist for advice.


Stiff jaw

Certain muscles in your face help to move your jaw. The muscles can become stiff during radiotherapy or surgery to the back of the mouth and throat (pharynx). This is called Trismus. Your doctor or dentist may suggest some gentle jaw exercises to help prevent this becoming a permanent problem. If you are concerned, you can talk to a physiotherapist or speech and language therapist at the hospital. Ask your doctor, radiographer or nurse to refer you.


Pain when swallowing

If your cancer treatment makes your mouth sore and dry, this can make swallowing very difficult. Eating moist foods and sipping water may help. Do let your doctor know if you are in a lot of pain. They can prescribe painkillers to help you get through this difficult time.


Loss of appetite

If you have mouth problems you may lose your appetite, and this can lead to weight loss. If you are having problems eating because of treatment side effects, talk to your radiographer, doctor or nurse. They may refer you to a dietitian for advice. You will probably need to take food supplements, such as high calorie drinks, until your mouth feels better. Your doctor can prescribe these for you. You may lose some weight even if you take these supplements.

If you have such a sore mouth that you can't eat at all, your doctor may suggest liquid tube feeds until your mouth recovers. The liquid food is carried into your stomach by a very thin tube that goes up your nose (a nasogastric tube) or through the skin in your abdomen (gastrostomy tube). You may have to go into hospital to have the tube feeds, at least to start with.

For more information about diet or healthy eating, look at our coping with cancer reading list. We also have information about weight loss.

You can also contact our cancer information nurses. They would be happy to help.


Research into mouth problems

Doctors are looking at ways to prevent mouth problems after cancer treatment, or make the problems less severe. And they also want to find better ways to help people who develop mouth problems. You can find detailed information about some of the trials mentioned below on our clinical trials database.

Research is looking into

Treatment to protect the salivary glands

A drug called amifostine might help to stop damage to salivary glands during radiotherapy. A few minutes before each radiotherapy treatment, you have amifostine injected into a vein in your arm. It seems to limit radiation damage to the salivary glands. Fewer people have problems with a dry mouth during radiotherapy treatment if they have amifostine. It also seems to help to prevent mouth infection. Amifostine is still experimental and not used as standard treatment. Doctors don't all agree about using it. Some are worried that the amifostine may protect cancer cells, as well as healthy cells. Side effects of amifostine include low blood pressure, dizziness, flushing, chills, and sickness.

Low-level laser therapy

A number of trials have looked at low-level laser therapy (LLLT) to help prevent or treat a sore mouth (mucositis) caused by cancer treatment. Doctors think that LLLT might help with pain and inflammation and make mouth problems less severe after certain treatments. The research has focused on people having radiotherapy for head and neck cancers, and people having high dose chemotherapy and stem cell transplants. There is evidence from trials that LLLT makes mouth problems less severe. There is ongoing research looking at LLLT, particularly in Europe. At the moment it may only be available in a few specialist hospitals in the UK.


Palifermin (Kepivance) is a drug that doctors may use in some people having a stem cell transplant to prevent or treat mouth soreness and inflammation (mucositis). It stimulates the growth of cells in the lining of your mouth and digestive tract. It aims to reduce the chance of developing severe mucositis and speeds up recovery time. You have it as an injection into a vein once a day for 3 days before starting high dose chemotherapy and radiotherapy, and for another 3 days afterwards. The evidence so far is encouraging and it is licensed for use in the UK. However, it is not currently used in the NHS. You may have it as part of a clinical trial. Side effects include a skin rash, taste changes and general swelling (oedema).

Part of the UKALL14 trial for acute lymphoblastic leukaemia is looking at 2 doses of palifermin to see if it helps stop people who have a stem cell transplant getting a sore mouth. 

Ways of reducing dry mouth symptoms

Doctors are looking at ways to reduce the symptoms of a dry mouth after cancer treatment. The LEONIDAS-2 study is for people who have had radiotherapy for head and neck cancer. This trial is looking at a new device that delivers a mild electrical stimulation to the gums. Doctors think that mild electrical stimulation to the skin of the mouth might increase the amount of saliva you make. This study has closed and we are waiting for the results.

There is a trial looking at a new drug called APD515 to see if this helps with a dry mouth. A dry mouth can be treated with artificial saliva sprays and mouth gels. But these treatments don't always work very well. APD515 is a liquid that you spread onto the lining of your mouth and leave there for 2 minutes. The trial is now closed and we are waiting for results.

Treatments for a stiff jaw

Some people find it difficult to open their mouth properly after radiotherapy for mouth or oropharyngeal cancer. This is because radiotherapy can affect the muscles that you use to open and close your mouth. It is called trismus. 

Trismus can be treated by gently stretching the jaw muscles using wooden spatulas. The Trismus trial is comparing this with the Therabite device. This is a hand operated device you put inside your mouth. The aim of the trial is to see which is best to treat trismus. And to find out which improves quality of life the most and which exercise routine people stick to best. This trial has closed and we are waiting for the results.

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Updated: 30 July 2015