Mouth problems

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"It was painful to eat and talk because every time I opened my mouth, I felt like my teeth were catching on these little blisters on the insides of my cheeks."
Penny
Diagnosed with bowel cancer
Topics covered on this page:

What is a cancer-related mouth problem?

Mouth problems can be a side-effect of cancer treatment or the cancer itself. They may cause pain, soreness, dryness or other problems in your mouth or throat.

  • How does it affect me? You might have painful sores in your mouth. Your saliva (spit) might be a bit thicker than normal and you may also have a dry mouth. These mouth problems may make it harder for you to eat, swallow or talk as you normally would.
  • Does it get better? Cancer-related mouth problems may get better or go away during or after you finish cancer treatment. Some mouth problems, like a dry mouth, can stay for a longer time. There are strategies that can help you manage mouth problems (see strategies in the section What can I do to help manage my mouth problem?​).

What causes a mouth problem?

Many people will eventually have some kind of mouth problem when they receive cancer treatment. Treatments damage cancer cells and can also damage healthy cells in your body, like those that line your mouth and throat. Factors that may cause you to have mouth problems include:

  • The cancer itself, such as head and neck cancer.
  • Radiation therapy (more common for head and neck cancer).
  • Some chemotherapy drugs.
  • Increased number and strength of treatments.
  • Not brushing your teeth regularly.
  • Not drinking or eating enough during treatment.
  • Smoking or chewing tobacco.
  • Breathing through your mouth instead of your nose.
Mouth problems signs

What are the signs of mouth problems?

Mouth problems can present in a number of ways and signs can include:

  • Dry mouth
  • Thicker saliva
  • Thick-feeling tongue
  • Pain or burning sensation in the mouth
  • Changes in how food tastes
  • Ulcers (small sores in the mouth)
Mouth problems doctor

When should I get help for my mouth problems?

It is normal to have some mouth problems when you have cancer. However, you should talk to your doctor, nurse, or pharmacist if your mouth problem causes any of the following (for tips on talking with your healthcare team see  Talking to your healthcare professional about your symptoms or concerns):

  • Pain that makes it hard to eat, drink, swallow or talk.
  • Difficulty with daily activities.
  • Soreness that doesn’t allow you to use a toothbrush.
  • White patches or spots in your mouth.
  • Open sores or ulcers in your mouth.
  • A blistered or cracked tongue.
  • Bleeding gums.
  • A very dry mouth that makes it difficult to swallow.

Talk to someone in your healthcare team immediately if:

  • You are on active chemotherapy and your gums bleed for more than 2 minutes after you floss.
  • You have pain that is not relieved by medication or other treatments.
  • You are unable to drink fluids or take your medication for 24 hours or more.

Go to the emergency department if:

  • You have fever (temperature taken in your mouth) of 38.0°C (100°F) or more, for over an hour.
  • You have fever (temperature taken in your mouth) of 38.3°C (101°F) anytime.

What can I do to help manage my mouth problem?

It is important that you inform your healthcare team of your mouth problems as they can recommend management strategies. There are many ways to manage your mouth problems or to keep them from getting worse—you can try the following suggestions and see what works best for you.

  • Before you start any treatment, have a checkup with your dentist to clean your teeth and repair any cavities.
  • If you receive radiation therapy for head and neck cancer, your team members will teach you special mouth care.
  • Check with your doctor if you should continue to floss.
  • Use a small, soft bristle, rounded-end toothbrush. You can change your toothbrush when the bristles are not standing up straight.
  • Try a non-abrasive, fluoride toothpaste with a neutral taste. Flavoring agents can irritate your gums.
  • Brush two to four times every day, after eating and before bed. Try rinsing your toothbrush in hot water before using it to soften the bristles.
  • Try to avoid tobacco.
  • Rinse, swish and spit with an alcohol-free mouth rinse or water several times after brushing, eating and as needed
  • Try and avoid rinses with club soda or mouthwashes that contain alcohol—these can dry and irritate your mouth.
  • Ask your healthcare team to suggest what mouth rinse to use, how often to use it and when to use it.
  • You can also make a homemade mouth rinse:
    • Mix ½ teaspoon of baking soda and ½ teaspoon of salt into 2 cups of water (or
      1 teaspoon of salt into 2 cups of water). Make the rinse fresh every day and keep it at room temperature.

Keeping your mouth wet will help you avoid having thicker saliva (spit) or a dry mouth.

  • Rinse your mouth with water or mouth rinse every 1 to 2 hours or spray your mouth with mouth rinse, water or artificial saliva products as needed to keep it moist.
  • Apply mouth lubricant that your team has recommended you to use as needed. In particular, apply after you brush your teeth, at bedtime, and as needed.
  • Do not use glycerin or lemon-glycerin swabs, they can dry your mouth.
  • Use sugarless gum or lozenges to help keep your mouth moist.
  • Use a steam vaporizer at night to relieve nighttime dry mouth.
  •  
  • Protect your lips with lip balm to help them stay moist and avoid cracking.
  • Use animal or plant-based lip balm and avoid petroleum-based balms. Choose a lip balm with SPF 30 or higher to protect your lips from the sun.
  • You may want to apply lip balm after brushing your teeth, at bedtime, and as needed.
  • Do not touch any lip sores or lick your lips too often.
  • Try and limit stress and sunlight if you have cold sores or have had them in the past.

If you have dentures, then take a few steps to avoid getting mouth sores from them:

  • Remove your dentures, plates and prostheses before cleaning your mouth.
  • Brush and rinse your dentures after meals and at bedtime.
  • Do not wear your dentures more than 16 hours a day, and take them out when you are sleeping.
  • Rinse your dentures with mouth rinse when you remove them and before you put them in again.
  •  

A balanced diet will help you avoid mouth problems and give you more energy. Here are some eating tips for when it hurts to swallow or chew:

  • Try to drink enough fluids during the day to remain hydrated (8-12 cups). You can drink water, non-acidic juices, ice cubes, sports drinks or broth.
  • Avoid food that is acidic, salty or spicy and dry or coarse foods.
  • Eat your food at room temperature, not too cold or too hot.
  • Eat a soft diet – try puréed food or add liquids like sauce, dressing, gravy, broth or butter/ margarine.
  • Take small mouthfuls.
  • Limit drinks high in sugar, acidic juices (like orange juice that can sting sores) and caffeine. Use a straw to bypass any sores.
  • Stay away from carbonated drinks (soft drinks), these are very acidic and can cause mouth sores and cavities.
  • Try to avoid alcohol as this can hurt your mouth.

⚠ Important information about cannabis

Some patients do use cannabis to reduce pain, help with relaxation or as a sleeping aid. However, the research is still unclear about the use of cannabis to manage cancer-related symptoms, including mouth problems. It is important to talk to your doctor before trying cannabis. For more information on what cancer patients should know about cannabis, go to: www.bccancer.ca/health-info/coping-with-cancer/medical-cannabis. 

Resources

For more information on cancer-related mouth problems, self-management strategies and support organizations, check out the resources below.

McGill University Health Centre – Going Home After Chemotherapy

BCCA – Dry Mouth and Mouth Pain Patient Handout

Cancer Net – Dry Mouth or Xerostomia

Cancer Net – Mouth Sores or Mucositis

Canadian Cancer Society – Mouth care

Centre Hospitalier de l’Université de Montréal – Keeping Your Mouth Healthy During Cancer Treatment

Cancer Care Ontario – Mouth Care During Cancer Treatment

Acknowledgement of sources​

The content of this document has been adapted from the following sources:

  • BC Cancer Agency. Dry Mouth and Mouth Pain from Cancer Treatments Patient Handout. 2020.
  • BC Cancer. Oral Mucositis. 2019.
  • Canadian Cancer Society. Mouth care. 2020.
  • Cancer Care Ontario. Mouth Care During Cancer Treatment. 2016.
  • Cancer Net. Dry Mouth or Xerostomia. 2018.
  • Cancer Net. Mouth Sores or Mucositis. 2020.
  • Centre Hospitalier de l’Université de Montréal. Keeping Your Mouth Healthy During Cancer Treatment. 2018.
  • Coping Together. Getting on Top of Symptoms: Prevention and management of mouth sores. 2013.
  • COSTaRS. Mouth Dryness/Xerostomia. 2020.
  • COSTaRS. Mouth Sores/Stomatitis. 2020.
  • McGill University Health Centre. Going Home After Chemotherapy. 2016.

Healthcare professional endorsement

The content of this document has been reviewed and approved by a team of healthcare professionals and clinical experts.

Disclaimer

Please note that this fact sheet is not intended as a substitute for consultation with a healthcare professional. Rather, it was designed to complement interventions by your treating team. If you have questions about your health, or any medical issue, you should contact a healthcare professional right away. You should not delay seeking medical advice, or disregard professional medical advice, because of information in this fact sheet. Before beginning any health treatment, always consult your doctor. All care has been taken to ensure that the information contained in this document is accurate at the time of publication. e-IMPAQc is not responsible for any injury or damage to persons or property arising out of, or related to, any use of the fact sheet, or because of any errors or omissions.

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