This article explains why mouth sores occur in people undergoing cancer treatment. It also lists the types of food you can and cannot eat—as well as the way to eat—to better cope with treatment-induced oral mucositis.
How Cancer Treatment Causes Mouth Sores
Over 40% of people undergoing certain cancer treatments will develop oral mucositis. It is most commonly associated with chemotherapy but can also occur with radiation therapy to the head or neck.
Treatment-induced oral mucositis is the result of the following processes:
Whenever cells are damaged by chemotherapy or radiation, they release unstable atoms called free radicals. This, in turn, triggers the release of inflammatory chemicals called cytokines and metalloproteinase that break down a structural protein called collagen, causing tissues to thin and form ulcers. When this occurs in the mouth, natural bacteria quickly move into the sores, causing infection, inflammation, and pain.
The sores can often be extremely painful, making it difficult to eat, talk, and swallow. The sores may even extend into the esophagus that carries food from the mouth to the stomach.
Foods to Eat If You Have Mucositis
Generally speaking, you will want to eat foods that are soft, non-acidic, non-spicy, and not overly hot if you have oral mucositis. The less you have to chew, the better.
Among the foods recommended for people struggling with oral mucositis are:
Scrambled, poached, or boiled eggsCanned tuna fishStewed meatsSoft noodles and pastaWell-cooked white riceMashed vegetables, including potatoes sweet potatoes, peas, carrots, etc. Creamed spinach or cornCreamed or pureed soupsBaked beansTofuDairy products like milk, yogurt, and cottage cheeseSoft white breadCooked cereals, such as cream of wheat or thinned oatmealPancakesApplesauceBananasWatermelon, cantaloupe, papaya, and honeydew melonSoft stone fruits with thin skins, like peaches and nectarinesStewed or baked fruitsSmooth peanut butterCustards and puddingsGelatin dessertsPopsicles, ice cream, and frozen yogurtProtein shakes, smoothies, and liquid nutritional supplementsCaffeine-free teaNon-acidic juices, like apple juice or fruit nectars
Food to Avoid
There are certain foods that can aggravate mouth sores and make the pain worse. Even before starting cancer treatment, take heed of the types of food you should avoid, including:
Tough cuts of meatRaw or undercooked vegetablesTough or chewy bread, like bagelsCrunchy foods, such as pretzels, crackers, chips, or dry cerealTart or acidic foods, including tomatoes and citrus fruitsSalty or spicy foodsNuts or seedsHard or stringy fruits, like raw apples or mangosFruits with skins, like plumsFruits with little seeds, like strawberries, that can get stuck in soresHot foods, including soup and piping-hot beveragesCaffeinated beverages, including coffee, black tea, and colasAlcohol, including beer, wine, and liquor
How to Eat if You Have Oral Mucositis
Oral mucositis can be difficult to avoid when undergoing cancer treatment. Still, there are things you can do to get the nutrition you need without worsening the pain. This not only involves the types of food you eat but also the way that you eat.
Among some of the more helpful tips:
Eat smaller, more frequent meals: Instead of three large meals a day, try five to six snack-sized meals that place less stress on the mouth. Take smaller bites: It often helps to cut your food into small pieces before starting to eat. Puree your food: If your mouth is too sore to chew, get a blender and puree it. Moisten your food: Gravy and broth are not only ideal for softening food but also provide added nutrition. You can also make food more slippery with a splash of olive oil or canola oil. Use a straw: Sucking drinks through a straw can help you bypass mouth sores.
Coping with Oral Mucositis
In addition to being mindful of what and how you eat, the following can also help you manage mouth sore pain if you have oral mucositis:
Two servings of proteinTwo servings of dairyFive servings of fruits and vegetablesEight to 10 glasses of water or liquids
Drink ice water or suck on ice chips to cool the mouth and bring down inflammation. Take care of your teeth and gums by gently brushing and flossing. Gargle with Magic Mouthwash, which is specifically formulated for oral mucositis. Use an over-the-counter oral numbing spray like Chloraseptic. Quit smoking, which not only increases the risk of oral mucositis but makes it worse.
How to Deal With Dry Mouth
In addition to mouth sores, radiation treatment can cause dry mouth (xerostomia). If you are experiencing dry mouth in addition to mouth sores, try the following to help keep the moisture levels up:
Chew sugarless gum to promote saliva production. Use a saliva substitute like OraCoat or Biotene. Stay well hydrated. Snack on water-filled fruits like grapes and watermelon,Avoid caffeine and alcohol, both of which can dry the mouth. Quit cigarettes.
Summary
Mouth sores are a side effect of chemotherapy and radiation. They can make it difficult to eat, drink, and swallow. You can relieve the pain with things like ice chips, Magic Mouthwash, numbing sprays, and eating smaller, more frequent meals.
The foods you eat can also make a big difference. Choose foods that are soft, well-cooked, cold, or pureed. Avoid spicy, hot, salty, acidic, or crunchy foods, as well as caffeine and alcohol.
A Word From Verywell
Preparation almost always makes cancer treatment easier. Before you even start chemotherapy or radiation, ask your cancer specialist or care team about their recommendations for managing mouth sores.
If mouth sores are undermining your nutrition or quality of life, let your doctor know. In severe cases, a medication called Kepivance (palifermin) can be prescribed. Delivered intravenously (into a vein), Kepivance stimulates the growth of mucosal tissues and helps reduce the size and pain of mouth sores.
