What is Oral Mucositis (Mouth Sores)?

What to Know BEFORE Cancer Treatment Begins

Managing Mucositis During and After Treatment

Most patients who have radiation or chemotherapy for oral, head and neck cancer will develop mouth and throat sores at some point during their treatment. This condition is called oral mucositis.

The surface of the mouth and throat are made up of epithelial cells, which are a type of cells that grow and divide quickly. Radiation and chemotherapy are designed to target and kill cells that grow quickly, like cancer cells. But they can also damage other types of fast-growing cells, including “good” cells like those in the mouth and throat. This damage causes oral mucositis.

The mouth is the most common site for mucositis, but it can also occur in the throat. The parts of the mouth that are most likely to be affected are the inside of the cheeks and lips, and the tongue (especially the sides and bottom).

Oral mucositis can range from mild to severe. In mild cases, the sores may be small and only cause a little discomfort. In the most severe cases, sores are large, widespread, and extremely painful. 

Risk Factors

Chemotherapy and radiation to the head and neck are the biggest risk factors for developing oral mucositis. Half of all patients receiving chemotherapy, as well as most patients getting radiation, will develop mucositis.

Other risk factors include:

  • Poor oral hygiene
  • Poor dental health
  • Smoking or using tobacco products, including chewing tobacco
  • Using alcohol
  • Not drinking enough fluids
  • Dry mouth
  • Sex — Women are more likely to develop mucositis than men
  • Age — Younger patients are more likely to develop mucositis than older patients
  • Having another disease, such as diabetes, HIV/AIDS, kidney disease, etc.


Oral mucositis develops during cancer treatment. The timing usually depends on your treatment. With chemotherapy, it tends to develop 5-10 days after receiving chemo drugs. It lasts an average of 1-2 weeks and will get better once your white blood cell counts return to normal. With radiation, mucositis develops 1-3 weeks after the start of radiation. If you develop mucositis from radiation, it will likely continue through the rest of your treatment. You’ll start to see improvement within 4-6 weeks following your last radiation treatment.


Oral mucositis usually begins with discomfort or pain in your mouth. The painful areas will then turn red, and eventually open sores will develop.

Symptoms that you may experience include:

  • Soreness, pain or discomfort in your mouth or throat
  • Red, shiny, or swollen areas in your mouth
  • Blood in your mouth
  • White patches or pus in your mouth
  • Sores in your mouth, gums, or tongue. Sores may be covered by a white or yellow buildup.
  • Trouble swallowing or talking
  • Pain or trouble while eating or drinking
  • Increased mucus or thick saliva

Side Effects & Complications of Oral Mucositis

Oral mucositis is one of the most common side effects of cancer treatment, and it can be one of the most debilitating. There are possible complications that patients and their caregivers should keep in mind, including:

  • Nutritional problems: Pain, mucus, thick saliva, and too much or too little saliva can make eating and drinking difficult or impossible. You may not want to eat or drink, but that can result in weight loss, poor nutrition, and dehydration. Poor nutrition can slow the healing of the sores and make it harder for your body to fight the cancer and/or recover from treatment. If eating is too painful, you should consider a temporary feeding tube until your symptoms clear up.
  • Increased risk of infection: Because there are open sores in your mouth, bacteria, viruses, and fungi could have an easier way to invade your body, causing infections in the mouth or other parts of the body.
  • Increased risk of sepsis: Patients with neutropenia (not enough white blood cells) are four times more likely to develop sepsis (septicemia) than other patients. Sepsis is a complication that sometimes develops when your body is fighting an infection. Your body’s response to the infection causes widespread inflammation throughout the body that can cause organ damage, failure, and death.
  • Disruption of treatment: If mucositis becomes severe, your treatment(s) may have to be stopped for a while or the dosages of your treatment(s) may need to be adjusted.
  • Quality of life: Oral mucositis can severely reduce your quality of life. Patients often say that mucositis was the most difficult side effect of their treatment. The good news is that it is temporary. But, if you’re struggling at any time with the physical or emotional effects of mucositis, please consult your medical team right away.

Before You Begin Cancer Treatment

While most head and neck cancer patients will experience some degree of mucositis during treatment, there are some things you can do before beginning treatment to reduce your chance of developing the condition.

  • Get a recommendation/referral to a dentist who is knowledgeable and experienced working with cancer patients, and have an exam.
  • Make sure any dental issues are corrected prior to starting to treatment. If you need any dental work, including fillings or extractions, have the procedures done 4-6 weeks before starting radiation or chemotherapy.
  • If you wear dentures or another oral prosthetic, make sure they fit properly.
  • Ask your medical team about medications or treatments that may reduce the risk of developing oral mucositis. These may include:
  • Photobiomodulation therapy: A type of light therapy that may prevent oral mucositis if used before you begin cancer treatment. This therapy is new to guidelines for treatment of mucositis, and shows great promise without side effects. Learn more.
  • Amifostine (Ethyol®): A drug that protects the salivary glands and oral mucosa against damage caused by radiation.
  • Benzydamine: A medication that may prevent mucositis in patients receiving moderate-dose radiation.
  • Ask your doctor about having a feeding tube placed before you begin treatment. That way, it is already in place when or if eating becomes too difficult. Waiting to get a feeding tube until you need one can result in a medical and nutritional crisis, but it is a crisis that can be prevented by planning ahead. Many people dislike the idea of having a feeding tube. But remember: Just because you have a feeding tube, doesn’t mean you have to use it. You can continue to eat and drink normally for as long as you are able. The tube is easily removed once your risk of mucositis has passed.

Managing Oral Mucositis During and After Treatment

Once oral mucositis begins, there are steps you can take to help relieve pain and symptoms. Some basic tips include:

  • Stop smoking and/or using tobacco products
  • Avoid alcohol
  • Drink lots of fluids
  • Make sure your diet includes lots of protein, which helps your body rebuild and repair itself
Eating and Drinking

Although it may be painful, it is important to make sure you’re eating and drinking enough. To reduce pain and discomfort while eating, choose foods that soothe the mouth, such as:

  • Cold foods, including popsicles, frozen fruit, and ice cream
  • Soft, mild foods such as cottage cheese, smoothies, and yogurt
  • Well-cooked, soft meals such as potatoes, macaroni and cheese, casseroles, stews, and pasta in white sauce
  • Drink through a straw to avoid sore spots
  • Moisten food with sauces, gravies, or dressings to make it easier to eat.

Stay away from foods that could irritate your mouth or promote bacterial growth including:

  • Acidic foods, such as citrus fruit, tomatoes, peppers, and vinegar
  • Spicy foods
  • Crunchy or hard foods such as crusty bread, pretzels, and chips
  • Hot foods
  • Alcohol and carbonated drinks
  • Sugary snacks
Oral Care

It is important to take good daily care of your mouth, especially during treatment and if mucositis develops.

  • Toothbrushing helps keep the mouth moisturized, and it helps prevent infection. Brush gently at least twice daily. Some patients find it helpful to brush every 4 hours and at bedtime.
  • Use a soft-bristle toothbrush. Some patients find it easier and more comfortable to brush with a foam brush with an antibacterial rinse. Do not use lemon or glycerin swabs.
  • Use a gentle, mild-tasting toothpaste with prescription-strength fluoride, such as Prevident.
  • Do not use whitening toothpastes.
  • If flavored toothpastes irritate your mouth, use plain baking soda.
  • Floss gently once a day.
  • Rinse your mouth frequently with a product such as Peridex or Periogard to prevent infection. Salt water also provides many of the same benefits of moisturizing and cleaning.
  • Be sure to avoid mouthwashes that contain alcohol because alcohol can dry and irritate the tissues of the mouth.
  • Avoid using toothpicks, which can cut your mouth.
  • Use lip balm or moisturizer to keep your lips moist. Avoid using Vaseline because it can promote bacteria growth.
  • Rinse your mouth before and after meals and at bedtime with a baking soda rinse to relieve pain and clean out mucus buildup. A good recipe is ½ tsp salt, 1 tsp baking soda, and 1 quart of water. Be sure to RINSE and SPIT – do not swallow! Prepare a fresh batch each day. Additional tip: If the salt makes the rinse too painful, reduce the amount until it is no longer uncomfortable.
  • If you wear dentures, remove them whenever you can so your gums can be exposed to the air. If your gums are sore, only wear your dentures while eating. If your sores are severe, do not wear your dentures at all. If your dentures are loose or fit poorly, do not wear them at all. Poorly fitting dentures may rub against your mouth and can cause irritation that leads to more sores.
What Your Doctor Can Do

Pain from mucositis can range from mild to severe. To help manage pain, try the following.

  • Suck on ice chips or popsicles, and sip cool drinks often throughout the day.
  • Topical pain relievers, including lidocaine, benzocaine, or dyclonine hydrochloride may provide temporary relief.
  • Be sure to clean your teeth and mouth after meals and before applying any topical coating agent or medication for pain relief.
  • In severe cases, you may need a prescription for a pain medication.
  • Many resources suggest using “magic mouthwash” – a mixture of lidocaine (a pain reliever), diphenhydramine (an antihistamine and anti-inflammatory), and Maalox. “Magic mouthwash” should be used with caution because Maalox can cause drying of the lining of the mouth, which can make mucositis worse.
What Your Doctor Can Do

Like most side effects of cancer treatment, managing mucositis may require a team effort by your medical team and might involve your physician, nurse, dietician, dentist, and even your mental health provider. If you begin to notice signs and symptoms of mucositis, talk to your medical team as soon as possible. If you’ve already seen your doctor for mucositis, let them know right away if your sores get worse, if you develop white patches or pus in your mouth, or if you develop a fever higher than 100.4 degree. These could be signs of a serious complication.

Your doctor or medical team may prescribe medications to manage oral mucositis, including corticosteroids (anti-inflammatory drugs). Other medications that may be prescribed are Gelclair® and Zilactin®. These medications coat and protect the mucus membranes and nerves exposed by sores.

Your medical team may also recommend photobiomodulation therapy, a type of light therapy that may reduce the severity or duration of oral mucositis. This therapy is new to guidelines for treatment of mucositis as of summer 2019. Studies completed so far show good results without side effects. Learn more. 

Oral Mucositis Resources

Oral Care Tips from Survivors

Find out how other head and neck cancer survivors manage their oral care during and after treatment.

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