Author: Suzanne Dixon, MPH, RD

The loss of appetite is common when undergoing cancer treatment, particularly if you get a common side effect called oral mucositis which causes mouth sores. To ensure proper nutrition to help you heal, you need to find non-irritating foods that you can eat even if you have mouth sores.

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.

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.1

Oral mucositis is an especially common occurrence when exposed to the chemotherapy drugs 5-fluorouracil (5-FU) or Evomela (melphalan). Other chemotherapy drugs can do the same.2

Treatment-induced oral mucositis is the result of the following processes:

  1. Whenever cells are damaged by chemotherapy or radiation, they release unstable atoms called free radicals.
  2. 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.
  3. When this occurs in the mouth, natural bacteria quickly colonize 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 the chew, the better.

Among the foods recommended for people struggling with oral mucositis are:
Scrambled, poached, or boiled eggs
Canned tuna fish
Stewed meats
Soft noodles and pasta
Well-cooked white rice
Mashed vegetables, including potatoes sweet potatoes, peas, carrots, etc.
Creamed spinach or corn
Creamed or pureed soups
Baked beans
Dairy products like milk, yogurt, and cottage cheese
Soft white bread
Cooked cereals, such as cream of wheat or thinned oatmeal
Watermelon, cantaloupe, papaya, and honeydew melon
Soft stone fruits with thin skins, like peaches and nectarines
Stewed or baked fruits
Smooth peanut butter
Custards and puddings
Gelatin desserts
Popsicles, ice cream, and frozen yogurt
Protein shakes, smoothies, and liquid nutritional supplements
Caffeine-free tea
Non-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 meat
Raw or undercooked vegetables
Tough or chewy bread, like bagels
Crunchy foods, such as pretzels, crackers, chips, or dry cereal
Tart or acidic foods, including tomatoes and citrus fruits
Salty or spicy foods
Nuts or seeds
Hard or stringy fruits, like raw apples or mangos
Fruits with skins, like plums
Fruits with little seeds, like strawberries, that can get stuck in sores
Hot foods, including soup and piping-hot beverages
Caffeinated beverages, including coffee, black tea, and colas
Alcohol, 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 squares 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.

Nutritional Goals
It is important to maintain balanced nutrition each day. To do so, you need to eat:3
Two servings of protein
Two servings of dairy
Five servings of fruits and vegetables
Eight to 10 glasses of water or liquids

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:4

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:5

Chew sugarless gum to promote saliva production.
Use a saliva substitute like OraCoat or Salivea.
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.

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.


  1. Barbosa SCM, Pereira VBM, Wong DVT, et al. Amifostine reduces inflammation and protects against 5-fluorouracil-induced oral mucositis and hyposalivation. Braz J Med Biol Res. 2019;52(3):e8251. doi:10.1590/1414-431X20188251
  2. Chaveli-Lopez B, Bagan-Sebastian JV. Treatment of oral mucositis due to chemotherapy. J Clin Exp Dent. 2016 Apr;8(2):e201–9. doi:10.4317/jced.52917
  3. American Cancer Society. American Cancer Society guideline for diet and physical activity.
  4. Georgiou M, Patapatiou G, Domoxoudis S, Pistevou-Gompaki K, Pananikolaou. Oral mucositis: understanding the pathology and management. Hippokratia. 2012 Jul-Sep;16(3):215–6.
  5. Villa A, Connell CL, Abati S. Diagnosis and management of xerostomia and hyposalivation. Ther Clin Risk Manag. 2015;11:45-51.