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Dry Mouth and Mouth Pain

Xerostomia (dry mouth) and oral mucositis (redness and sores) are common side effects of cancer treatment.

Handout (English): Dry Mouth and Mouth Pain

Handout (Punjabi): ਕੈਂਸਰ ਟ੍ਰੀਟਮੈਂਟ ਕਾਰਣ ਖ਼ੁਸ਼ਕ ਮੂੰਹ ਅਤੇ ਮੂੰਹ ਦਾ ਦਰਦ

Handout (Traditional Chinese): 癌症治療所致的口乾和口痛問題

Dry mouth happens when there is less saliva (spit) in your mouth than is normal for you. Dry mouth is also called “xerostomia” (zeer-uh-stoh-mee-uh). 


Oral mucositis (mew-koh-si-tiss) causes redness, sore spots and ulcerations in your mouth and throat. This can make it hard for you to eat, swallow and talk.

Signs of oral mucositis:
  • Pain and sores in and around your mouth and throat.
  • Sometimes the pain and sores are in the intestinal tract. This can cause pain when you swallow, nausea, diarrhea and sometimes infections.

Dry mouth is a common side effect of radiation therapy and some cancer drugs. It is more common in older people.

These cancer treatments can cause redness and sores in your mouth:
  • Radiation treatment for head and neck cancers.
  • Stem cell transplant therapy.
  • Some chemotherapy drugs.

Dry mouth may get better or it may be permanent (it will never go away), depending on what is causing it. 

Oral mucositis may continue up to a few months after cancer treatment. 

Permanent dry mouth and oral mucositis are more common in patients who have had radiation therapy for head and neck cancer.  

Tell your health care team if you have dry mouth, redness, pain or sores in your mouth or throat.  

If your oral mucositis is not treated, it can interrupt your cancer treatment. Oral mucositis may also cause you to worry, become depressed, or stop seeing your friends and family.

Before your cancer treatments start, you should visit your dentist. They will examine you and treat any dental problems. Problems like cavities, gum disease, infections, and broken or sharp teeth should be treated or fixed.

If you have dentures your dentist will also check that they fit well and are comfortable.  

Your health care team might prescribe medications to help with your mouth symptoms. They may give you a special oral rinse (mouthwash) or tell you to suck on ice chips.  

Do not use any other over-the-counter mouth rinses or gels. These may make your pain worse.  

If you having trouble eating and you are losing weight, your health care team may refer you to a BC Cancer dietitian. 

The most important thing you can do is to take care of your mouth. Start following the directions below two weeks before your treatment starts or as soon as you can.

If you grind or clench your teeth, wear your mouth guard to protect your teeth.

Brush your teeth

  • Brush your teeth for at least 2 minutes.
  • Brush within 30 minutes of eating.
  • Use a soft toothbrush.
  • If you have oral mucositis, use an SLS-free toothpaste. Check the ingredients on your toothpaste to make sure it does not contain SLS (Sodium Lauryl Sulphate).
  • If your mouth is very sore, do not use mint flavoured toothpaste

If your mouth is too sore to use a toothbrush, talk to your health care team.

Floss your teeth

  • If flossing is part of your routine, continue to floss once per day.
  • Floss at bedtime, before brushing your teeth.
  • Use waxed floss. This will slide between your teeth easier than unwaxed floss. 
  • If flossing is not part of your routine, do not start flossing unless your dentist tells you to.
  • Stop flossing if it is painful or your gums bleed for longer than 2 minutes. Tell your health care team if this happens.
  • If you use a Water Pik, make sure you put it on the lowest setting so you do not hurt your gums.  

Use an oral rinse

  • Oral rinses help keep your mouth moist and clean. 
  • Use this recipe for bland mouth rinse:
    • Put 500 mL (about 2 cups) of water into a water bottle.
    • Add 5 mL (1 teaspoon) of baking soda. Shake to dissolve.
    • If you do not like the taste of the mouth rinse, you can add 2.5 mL (1/2 teaspoon) of salt.
  • Use the oral rinse 3-4 times each day.  You may need to rinse up to 8 times each day. Talk to your health care team about what is right for you.
  • Follow these instructions each time you rinse:
    • Put 15mL (1 tablespoon) of rinse in your mouth.
    • Swish in your mouth for 1 minute.
    • Spit it out.
  • Use the oral rinse until your mouth returns to normal. This may take many weeks or months.
  • Rinse with bland mouth rinse or water after eating and drinking. Rinse after drinking Ensure® or sports drinks as these have a lot of sugar.

Food and drink

  • Drink at least 1.5-2 litres (6-8 cups) of fluids each day. Fluids include water, juice (not acidic juices like orange juice as these may hurt your mouth), herbal tea, soup, broths, sports drinks and liquid nutritional drinks like Ensure®.
  • Do not drink carbonated drinks (fizzy drinks) like pop. These are very acidic and can cause mucositis, more mouth pain and cavities. 
  • Do not drink alcohol as this will hurt your mouth.
  • Eat bland, soft foods. You need to eat a balanced diet with enough protein and vitamins. 
  • Talk to a BC Cancer dietitian if you are unsure about what foods to eat and drink.

Take care of your lips

  • If your lips are dry, use a lubricant that is water-soluble, wax-based, or oil-based. Lanolin-based lubricants are the best choice. 
  • Do not use petroleum-based lubricants, like Vaseline.
  • Put the lubricant on your lips after cleaning your mouth and teeth and at bedtime and as needed. 
  • Ask your health care team if you are not sure which lubricant to use.

Taking care of dentures

  • Leave dentures out of your mouth when you are sleeping.
  • As much as possible during your cancer treatment, leave your dentures out of your mouth during the day.
  • Take out your dentures before brushing your teeth.
  • Brush and rinse dentures after meals and before bed.
  • While you are sleeping, soak your dentures in a cleansing solution for at least 8 hours.
  • If you are using an anti-fungal mouth rinse, soak the dentures in the anti-fungal rinse. Or, brush your dentures with your anti-fungal rinse before putting the dentures in your mouth.  

Some things you should not do: 

  • Do not use alcohol-based mouthwashes or over-the-counter rinses. Even alcohol-free rinses may sting due to chemicals in it. It's best to use the bland mouth rinse.
  • Do not eat spicy, acidic or coarse foods.
  • Do not drink alcohol.
  • Do not smoke.

Talk with your health care team if you are having trouble with any of these instructions

Revised: September 2020

SOURCE: Dry Mouth and Mouth Pain ( )
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