Mouth Sores from Chemo: Why You Have Them and How to Get Rid of Them

Recipes to Soothe Mouth Sores During Cancer Treatment

Mouth sores from chemotherapy and other therapies are common when people are receiving care for cancers, including head and neck cancers and breast cancer.

These painful, blister-like sores may emerge shortly after treatment begins. How long the mouth sores last after chemo depends on several factors, including the type of cancer. It also may depend on what other treatments, such as surgery or adjuvant therapy drugs, are used to treat your cancer.

This article discusses the causes and symptoms of mouth sores, as well as complications. It offers some home remedies that may help mouth sores to heal faster and improve your quality of life.

woman using mouth wash from glass

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Causes of Mouth Sores During Therapy

Mouth sores are common during cancer treatment because chemotherapy and other drugs target rapidly dividing cells. Similar tissues, such as those in the mouth, are affected.

Cancer treatment relies on a range of therapies. Chemotherapy is known to lead to mouth sores, but so can radiation therapy and surgery.

Targeted therapy drugs, genetically-based treatments designed to target specific cancer cells, and some immunotherapy drugs, which work to boost the body's own immune responses to fight cancer, also may lead to mouth sores.

Bone marrow and stem cell transplants also may lead to mouth sores.

They occur due to inflammation of the mucus membranes in the mouth, called chemotherapy-related mucositis. Treatments and other factors most likely to lead to mouth sores include:

Between 20% and 40% of people who undergo chemotherapy for cancer will experience mouth sores. That number rises to 80% in people treated with high-dose chemo.

Symptoms

A sore mouth typically will develop about 5 to 10 days after you start chemotherapy. It will likely persist for a few weeks after treatment ends.

During that time, your mouth may become quite dry. Chemo sores look like a type of red rash, with white spots or patches.

The mouth tissue may be swollen, and it becomes quite painful. This can make eating, drinking, and swallowing painful. Some healthcare providers suggest taking your pain medication, if you have one prescribed, a half-hour before eating for this reason.

Prevention also can help. Ice chips to keep your oral mucosa moist may be good for chemo mouth, and if you're being treated for a head and neck cancer, specialist dental care may help you to avoid complications.

If you develop mouth sores, talk to your oncologist. Depending on the severity of your symptoms, they may recommend you make your own rinses, purchase a product such as Magic Mouthwash or Triple Rinse, or give you a prescription rinse.

Complications

Mouth sores from chemo can be easily treated, but you may experience complications.

Nutrition, for example, may be affected because of the challenges with eating and drinking. Mouth sores may also affect taste, adding to other digestive impacts often associated with cancer. This may lead to dehydration or, in the case of someone living with diabetes, difficulty with managing blood sugars.

Another common complication from mouth sores is infection. For example, between 39% and 62% of people whose salivary glands are affected by cancer treatment will develop a Candida infection. Infections also may follow radiation therapy, immunotherapy drug treatment, and stem cell transplantation.

Long-term complications also may include tooth cavities and related dental impacts, as well as psychological disorders such as depression.

Kids and Mouth Sores From Chemo

Children receiving chemo drugs are more at-risk for mouth sores than adults are. Symptoms are similar but dehydration may occur more easily. Depending on their age, ice pops, throat drops, and lip balm may help. As with adults, make sure they avoid spicy, hot, or roughly textured foods that hurt.

Chemo Mouth Rinse Recipes

Special mouth rinses can correct the balance of healthy bacteria in the mouth and provide soothing relief of the discomfort the sores can cause. They may help mouth sores to heal faster.

Make-at-home recipes for mouth rinses are easy to mix, and use ingredients most people have in their kitchen or medicine cabinet.

Different rinses may be better for different symptoms. Some rinses work better for some people than others, so you may want to try a few to see what works best. Different mixes may be used for mouth sores, crusted sores, and a problem called "gummy mouth."

They are used by swishing the liquid around in the mouth and then spitting it out. They can be used several times a day.

For Mouth Sores

For generalized mouth sores, a soda and salt mouth rinse or saltwater rinse may be helpful.

Soda and Salt Mouth Rinse

1/4 teaspoon baking soda
1/8 teaspoon salt
1 cup of warm water

Mix well until the salt dissolves. Rinse the mouth gently, being careful not to swallow the mixture. Follow this with a plain water rinse to clean out any remaining salt or soda.

Saltwater Mouth Rinse

1/4 teaspoon salt
1 cup of warm water

Mix well to dissolve the salt. This saltwater rinse is close to the natural chemistry of your own saliva, so it may make sores feel better. Rinse well with plain water to remove excess salt.

For Gummy Mouth

Salt and Soda Rinse for Gummy Mouth

Some chemotherapy drugs can increase the acidity in your mouth, leading to thick saliva that can be very annoying. This rinse works well for "gummy mouth."

1/2 teaspoon salt
2 tablespoons baking soda
4 cups of warm water

This rinse will help to neutralize the acid in your mouth and dissolve or loosen thick, gummy saliva. Don't drink it, just rinse and spit it out.

For Crusted Sores

Peroxide Rinse for Crusted Sores

If mouth sores are crusting over, it's important to allow the natural healing process in the body to continue, so a peroxide rinse should be used for no more than two days consecutively.

1 cup hydrogen peroxide
1 cup water or 1 cup salt water (1 teaspoon of salt in 4 cups of water)

Try using this rinse three or four times a day for two days. Don't use it for longer than that, because it could prevent mucositis from healing. Switch to a non-peroxide rinse for two days before returning to this mixture.

Make the rinse fresh every day and keep it at room temperature for a maximum of 24 hours. They can help to heal mouth sores from chemo naturally.

Coping with Mouth Pain and Sores

In addition to avoiding foods that can be painful and using mouth rinses, there are several other things that can be done to care for the mouth during chemotherapy. These can help ease the discomfort of mouth sores. You can:

  • Visit the dentist
  • Use a soft toothbrush when brushing teeth
  • Stay hydrated
  • Limit alcohol and caffeine
  • Avoid acidic fruits or juices
  • Avoid sharp, salty, or spicy foods
  • Eat soft, moist foods

When to Call Your Healthcare Provider

Mouth sores can sometimes become infected, and when your white blood cell count is low due to chemotherapy, this can be serious. Make sure to call your healthcare provider right away if you:

  • Develop a fever
  • Believe you may be dehydrated
  • Develop any yellow or foul drainage from your mouth
  • Have problems eating or drinking due to mouth sores

Summary

Mouth sores can be an uncomfortable side effect of chemotherapy, but they can be managed with use of mouth rinses. Rinses that contain water, salt, and baking soda can be used in a variety of recipes to treat the mouth.

Other steps to take care of the mouth during chemo include using a soft toothbrush, avoiding irritating foods, and staying hydrated. All of these can help mouth sores as well. Be sure to call your oncology team immediately if you develop a fever or signs of infection, or if you're unable to eat or drink.

A Word From Verywell

Mouth sores can be a distressing side effect of chemotherapy. Talk to your oncologist to see if they have any suggestions in addition to the rinses above to help manage the symptoms.

Frequently Asked Questions

  • What is the fastest way to cure mucositis?

    Giving the mouth time to heal is the best thing you can do to resolve mucositis. Nothing will make the tissue of the mouth heal more quickly, but using mouth rinses and avoiding sharp, spicy, acidic, or salty foods and drinks can help relieve discomfort and reduce irritation in the meantime.

  • Can Orajel help heal chemo mouth sores?

    Over-the-counter topical treatments such as Orajel can help manage mouth sore pain, but you should ask your oncology team before using them. For lips, use lip balm but avoid petroleum jelly.

  • What is Magic Mouthwash?

    Magic mouthwash is a prescription mouth rinse that usually contains lidocaine to numb the mouth, along with an antihistamine and other medications to soothe the mouth.

  • What can you do to prevent chemo mouth sores?

    Certain chemotherapy medications are more likely to cause mouth sores than others. The cancer team may recommend sucking on ice chips and similar comfort measures. They also may use a drug called Kepivance (palifermin) to reduce the risk of mucositis.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Taichman LS, Van Poznak CH, Inglehart MR. Oral health-related concerns, behavior, and communication with health care providers of patients with breast cancer: impact of different treatments. Spec Care Dentist. 2018 Jan;38(1):36-45. doi:10.1111/scd.12266. 

  2. American Cancer Society. Mouth sores and pain.

  3. American Society of Clinical Oncology (ASCO). Mouth Sores or Mucositis.

  4. Cancer Research UK. Your mouth and cancer drugs.

  5. Viana ECRM, Oliveira IDS, Rechinelli AB, Marques IL, Souza VF, Spexoto MCB, et al. Malnutrition and nutrition impact symptoms (NIS) in surgical patients with cancer. PLoS One. 2020 Dec 15;15(12):e0241305. doi:10.1371/journal.pone.0241305.

  6. Vistoso Monreal A, Polonsky G, Shiboski C, Sankar V, Villa A. Salivary Gland Dysfunction Secondary to Cancer Treatment. Front Oral Health. 2022 Jun 9;3:907778. doi:10.3389/froh.2022.907778.

  7. Cedars-Sinai. Chemotherapy-Related Mouth Mucositis in Children.

  8. Zhu G, Wang Q, Lu S, Niu Y. Hydrogen peroxide: A potential wound therapeutic target? Med Princ Pract. 2017;26(4):301–308. doi:10.1159/000475501

  9. Chaveli-López B, Bagán-Sebastián JV. Treatment of oral mucositis due to chemotherapyJ Clin Exp Dent. 2016;8(2):e201-e209.

Additional Reading

By Julie Scott, MSN, ANP-BC, AOCNP
Julie is an Adult Nurse Practitioner with oncology certification and a healthcare freelance writer with an interest in educating patients and the healthcare community.

Originally written by
Pam Stephan
Pam Stephan is a breast cancer survivor.
Learn about our editorial process