Chemotherapy, which people often refer to as chemo, is more likely to kill cancer cells than healthy cells because cancer cells tend to divide and multiply more quickly. However, this treatment also kills healthy cells that are in the process of cell division.
Damage to healthy cells inside the mouth can interfere with its ability to fight off harmful bacteria and to heal. This interference can result in the development of mouth sores.
In this article, we provide information on the symptoms, management, and prevention of mouth sores from chemo.
Sores are usually at their worst around the seventh day of chemotherapy.
Mouth sores are small cuts or ulcers inside the mouth.
They may appear a few days after a person starts chemotherapy, and they are usually at their worst around the seventh day following treatment.
Sores can appear on any of the soft tissues in or around the mouth, including the:
- floor of the mouth
- roof of the mouth
Symptoms to look out for include:
- red, shiny, or swollen areas inside the mouth
- bleeding in the mouth
- increased mucus in the mouth
- a white or yellow film covering the mouth or tongue
- sores with central white patches
- pus in the mouth
- pain in the mouth or throat
- dryness, burning sensations, or pain when eating hot or cold foods
Depending on the location and severity of the sores, a person may experience difficulties with the following:
Very painful mouth sores may lead to further complications, such as:
Mouth sores may develop a few days after starting chemotherapy, and they tend to clear up about 10–14 days after the treatment ends.
In the meantime, there are various ways in which people can shorten the duration of mouth sores, relieve symptoms, and prevent further complications.
We offer some tips below.
The following home remedies and lifestyle tips can help people manage mouth sores at home:
Keep the mouth moist
Keeping the mouth moist can help relieve mouth pain and irritation.
A person can usually achieve this by drinking eight 8-ounce glasses of water per day. Drinking through a straw can allow the water to bypass any painful sores in the mouth.
Other tips for keeping the mouth moist include:
- sucking on ice chips
- chewing sugarless gum
- sucking sugarless candy
Focus on diet
A person with a mouth sore should focus on eating soft, moist foods such as mashed potatoes.
Spicy, salty, and acidic foods can further irritate mouth sores.
People should also avoid eating foods that have a dry, hard, crusty, or sticky texture. These can be uncomfortable or painful to eat.
Examples of foods and drinks to avoid include:
- citrus fruits
- crusty bread
- pickled foods
- peanut butter
- fizzy beverages
- caffeinated drinks
When possible, a person should choose soft, moist foods that are easy to chew and swallow. Some healthful options include:
- stewed vegetables
- mashed potatoes
- scrambled eggs
- baked beans
- cooked cereals
- cottage cheese
It is important to ensure that these foods have cooled to room temperature before eating them. Hot or warm foods can further irritate a sore mouth.
Additional mealtime tips
The following practices can also help alleviate mouth soreness during mealtimes:
- taking small bites of food and chewing them thoroughly
- sipping water to reduce discomfort when swallowing
- taking pain relievers about 30 minutes before a meal
- coating mouth sores with numbing gels, such as benzocaine (Anbesol or Orajel), before mealtimes to prevent pain when eating
Keep the mouth clean
Keeping the mouth clean is important for preventing infection. However, cleaning a sore mouth can be difficult and painful.
The American Cancer Society (ACS) provide the following mouth care plan for people managing mouth sores:
Brushing the teeth
When mouth sores are present, people should floss the teeth daily, except in areas that are sore or bleed easily.
People should also aim to brush their teeth about 30 minutes after eating and every 4 hours throughout the day.
The following tips can help prevent mouth irritation when brushing the teeth:
- Use a toothbrush with extra soft nylon bristles. Soak the bristles in warm water before brushing to soften them further.
- If cleaning with a regular toothbrush is painful, use soft, foam mouth swabs to clean the teeth. These are available at many drugstores and online.
- Use a nonabrasive toothpaste containing fluoride.
- Avoid whitening toothpaste that contains hydrogen peroxide, as this can further irritate the mouth.
- After brushing, rinse the toothbrush in hot water and store it in a cool, dry place.
Rinsing the mouth
People should avoid using store bought mouthwash, which typically contains alcohol and other irritants.
Instead, the ACS recommend rinsing the mouth with one of the following mixtures:
- 1 teaspoon of baking soda
- 2 cups of water
- 1 teaspoon of sea salt
- 1 teaspoon of baking soda
- 1 quart of water
People should stir the solution thoroughly to ensure that the ingredients dissolve properly.
They can then gently swish it around in the mouth and gargle with it before spitting it out.
Caring for dentures
Wearing ill fitting dentures increases the risk of mouth sores during chemotherapy. People should avoid wearing them while receiving treatment.
Even properly fitting dentures can cause problems if sores develop underneath them. If this happens, a person should leave the dentures out between meals and at night to give the sores a chance to heal.
The ACS also advise people with dentures who are experiencing mouth sores to remove and clean the dentures between meals and store them in an antibacterial soak when they are not in use.
Caring for sore lips
Some people may experience sores on their lips. Applying the following products to the lips can help treat dryness or soreness:
- petroleum jelly
- cocoa butter
- a mild lip balm
Currently, there are no medications to prevent the development of mouth sores during chemotherapy.
However, people who regularly check their mouth are likely to detect sores at an earlier stage. Early detection and management of sores can reduce their duration and severity.
The ACS advise that people check their mouth twice a day using a small flashlight. Gently pressing a Popsicle stick onto the middle of the tongue will give them a more unobstructed view of the back of the mouth. People who wear dentures should remove them before checking for sores.
People should notify their healthcare team if they notice changes in the mouth or differences in how things taste.
When to see a doctor
If mouth sores are preventing a person from eating, they should talk to their doctor.
People should see a doctor if their mouth sores prevent them from doing any of the following activities:
- taking medication
A doctor will be able to prescribe medications to ease mouth pain and other symptoms.
A person should also see a doctor if they experience any of the following signs of infection:
- a fever higher than 100°F
- sores in or around the mouth that worsen despite proper management
- severe pain or other signs of infection
Chemotherapy drugs weaken the immune system, making it difficult for people to fight off infections. Early detection and treatment of infections help lower the risk of further complications.
Mouth sores are a potential side effect of chemotherapy. These sores usually develop within the first few days of starting the treatment.
The sores generally clear up about 10–14 days after the chemotherapy has ended. In the meantime, a person can try many techniques to manage the sores at home.
Successful home management can relieve symptoms, decrease the duration of sores, and prevent infection.
A person should see their doctor if mouth sores become very painful or if there are signs of infection. Early treatment of infection reduces the risk of further complications.