Sore mouth and infections

When the healthy cells in the lining of the mouth are impaired, this can lead to a number of oral health problems such as a sore mouth, dry mouth and/or mouth infections. Mouth problems can greatly affect quality of life.

Soreness and ulceration of the mouth

Certain treatments and medications 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 (which help fight infection) in your blood is 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, which your doctor can prescribe.

Bleeding gums

Occasionally some bleeding or ulceration of the gums may develop. Damage to the cells lining the mouth can be caused by some cancer treatments and in this case, it is usually temporary and most side effects will disappear once your treatment has finished.

The likelihood of developing a sore mouth can vary depending on your condition and/or any treatment you are receiving. Your doctor or nurse will be able to tell you how likely it is that you may develop a sore mouth and what signs to look for and what you could do, should this be the case.

How to keep your mouth healthy

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 can show you how to do this.

  • 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 plain water mouthwash.
  • 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.
  • Keep your lips moist by using a recommended lubricant.
  • 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 if you have, or are at risk of developing bleeding gums.
  • 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.

How your dentist can help you

Dentists can advise on any mouth problems caused by your treatment and can help you get your teeth and gums into the healthiest possible condition.

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

If you need to have dental work done during certain treatments, for example, chemotherapy, it may be important to discuss this with your doctor or nurse specialist. There might be times during your treatment when you’re at risk of bleeding and infection, meaning 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 treatment. Your teeth may be more prone to decay because of your treatment and it can be helpful to get a dental check-up.

How your doctor can help you

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 can help to prevent infection. Benzydamine mouthwash 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, or mixed with water and used as a mouthwash.

Mouthwashes to relieve pain

Sometimes soluble paracetamol or soluble co-codamol can be used as a mouthwash to relieve pain in the lining of the mouth. People having some treatments are advised not to swallow these medicines, but it is usually fine to use as a mouthwash. It is helpful to check with your doctor or nurse before using this type of mouthwash. 

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, which helps them work more effectively. If the painkillers are not helping the pain, and it is so severe that drinking is difficult, inform your doctor. Stronger painkillers, such as morphine or codeine, can make you constipated and therefore 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.

Oral thrush

If you have oral thrush (white patches in your mouth) this can be treated with anti-fungal drugs. There are different types of anti-fungal drugs.

Oral thrush is usually treated with a liquid dropped into the mouth (nystatin) or tablets such as fluconazole. Your doctor can prescribe these medicines.

Mucilages

Some hospitals prescribe mucilages to help to ease soreness. Mucilages are unmedicated jelly-like substances (lubricants).

Dry mouth

This information is about how you can help yourself if you are having problems with a dry mouth, which is also called xerostomia, and may be caused by treatment you are having.

Saliva

Saliva, or spit, is the fluid produced by the salivary glands, which are situated around the jaw and under the tongue. Saliva keeps the mouth clean and helps to prevent infection. It also protects your teeth, as a lack of saliva can increase your risk of developing tooth decay or gum disease.

When you eat, more saliva is produced to moisten the food, which makes it easier to chew and swallow, as well as beginning the process of digestion. A lack of saliva can change the taste of the food you eat and may also mean that you cannot swallow food so well.

Some radiotherapy treatments to the face or mouth, can affect the salivary glands, so that less saliva is produced. The glands may recover over time (sometimes this takes several months), but for some people the dry mouth may be permanent.

How your doctor can help

Drugs to stimulate saliva

It is important to tell your doctor if you have a dry mouth, as they may be able to prescribe medicines to help. Pilocarpine (Salagen®) is usually used. Sometimes a drug called bethanechol may be used instead of pilocarpine, although it's not licensed to treat dry mouth.

These drugs stimulate the salivary glands to produce saliva and will only work if the damage to the glands is temporary or partial. Two or three months of continuous treatment with pilocarpine may be needed before it is effective in stimulating temporarily damaged salivary glands to work again.

Unfortunately, pilocarpine does not work if the damage to the glands is permanent.

Like many drugs, pilocarpine has side effects. It can cause sweats, nausea and vomiting.

Artificial saliva

Artificial saliva products can also be helpful for moistening the mouth. As their effect may last only for a short time, it is best to use them just before meals and at night to prevent the dryness from disturbing your sleep. Several brands are available and they come in the form of a gel, spray, pastille or tablet. Your doctor can prescribe a product for if you inform them that you are having problems with reduced saliva. You may find it helpful to try more than one form of artificial saliva brand to find out which one suits you best.

How you can help yourself

Keeping your mouth clean

As saliva helps to keep your mouth clean, it is important to brush your teeth with a soft toothbrush after each meal, and to use mouthwashes regularly. However, mouthwashes containing detergents or alcohol should be avoided as they can dry and irritate the lining of the mouth. Your doctor or nurse will be able to advise you about the best mouthwash to use. Regular dental check-ups are essential too, as the risk of developing tooth decay is increased by a lack of saliva.

Encouraging saliva production

If your salivary glands are still able to produce some saliva, sucking sugar-free sweets or chewing sugar-free gum can encourage saliva production. Pineapple chunks, ice cubes, frozen tonic water, yoghurt and buttermilk can also be helpful, although some people find that very cold foods or drinks may be too uncomfortable to use.

Keeping your mouth moist

To keep your mouth moist you can drink sips of water or sugar-free fizzy drinks regularly throughout the day.

Cut down or avoid substances that can dry the mouth

These include alcohol, caffeine and cigarettes. Some prescribed medicines can also cause a dry mouth and it can be helpful to ask your doctor or nurse to identify these, as it may be possible to reduce the dosage or change the drug.

It may also be helpful to try acupuncture as this may sometimes increase the amount of saliva that is produced.

Boosting appetite

Many people can lose their appetite due to a dry mouth, or may find that foods taste different, which can cause eating difficulties. Here are some tips that can make food more palatable:

  • make sure you drink fluid with meals
  • include plenty of sauces and gravy with meals
  • include foods with a high fluid content, such as jelly, puréed fruits and soft puddings in your diet
  • avoid dry and 'thick' foods such as biscuits, crackers and dry snacks

Last updated:
26 February 2020