Mouth Sores


Causes of Mouth Sores

Chemotherapy kills cancer by interfering with the growth of rapidly dividing cells. Unfortunately, the mucous linings of the mouth are comprised of rapidly dividing cells, so chemotherapy can cause mouth sores.

The following chemotherapy drugs will cause mouth sores in more than one third of cancer patients: Actinomycin (Cosmegen), Busulfan (Myleran, Busulfex), Cytarabine (Cytosar-U), Daunorubicin (Cerubidine), Docetaxel (Taxotere), Doxorubicin (Adriamycin, Rubex), Epirubicin (Ellence), Floxuridine (FUDR), Fluorouracil (5-FU, Adrucil, Carac, Efudex, Fluoroplex), Idarubicin (Idamycin, Idamycin PFS), Isotretinoin (Accutane), Liposomal doxorubicin (Doxil), Methotrexate (Rheumatrex, Trexall), Mitomycin (Mutamycin), Mitoxantrone (Novantrone), Mechlorethamine (Mustargen), Oprevelkin (Neumega), Paclitaxel (Taxol, Onxal), Pemetrexed (Alimta), Plicamycin (Mithracin), Procarbazine (Matulane), Teniposide (Vumon), Trimetrexate (Neutrexin, TMQ, TMTX), Tretinoin (Vesanoid).

Mouth sores are less common with the following chemotherapy drugs, but still occur in at least 10% of cancer patients: Alemtuzumab (Campath), Asparaginase (Elspar, Kidrolase), Bleomycin (Blenoxane), Capecitabine (Xeloda), Carboplatin (Paraplatin), Cyclophosphamide (Cytoxan, Neosar), Etoposide (VePesid, Toposar, Etopophos), Gemcitabine (Gemzar), Gemtuzumab ozogamicin (Mylotarg), Hydroxyurea (Hydrea), Interleukin 2 (Proleukin), Irinotecan (Camptosar), Liposomal daunorubicin (DaunoXome), Lomustine (CeeNU), Melphalan (Alkeran), Oxaliplatin (Eloxatin), Pentostatin (Nipent), Rasburicase (Elitek), Thiotepa (Thioplex), Topotecan (Hycamtin), Trastuzumab (Herceptin), Tretinoin (Vesanoid), Vinblastine (Velban, Alkaban AQ), Vincristine (Oncovin, Vincasar PFS).

Mouth sores can also occur with radiation therapy, especially radiation therapy for head and neck cancer. High dose chemotherapy is more likely to cause mouth sores, as is chemotherapy that is given on a daily protocol as opposed to weekly.

Preventing Mouth Sores

Before you start chemotherapy, have a check-up and general cleaning at your dentist.

Sucking on ice chips while receiving the chemotherapy infusion may help prevent mouth sores. The cold reduces blood flow to the mouth, decreasing the likelihood of your getting mouth sores.

Drink plenty of water, as this will help prevent your mouth from drying out. Sucking on hard candy such as lemon drops or Creamsavers can also help by promoting saliva production. (Note that some sugar-free candy contains sorbitol, which can cause diarrhea, so check the ingredients before using sugar-free hard candy.)

A new drug, Kepivance (keratinocyte growth factor, palifermin), helps stimulate the growth of the lining of the mouth. It is currently undergoing clinical trials to determine whether it helps prevent mouth sores in cancer patients.

Minimizing Discomfort

Here are a few helpful hints for dealing with the discomfort.

  • Avoid eating hot, salty, acidic (e.g., orange juice, grapefruit, lemon, lime and other citrus, tomato, V-8 juice, pickles), sour or spicy food and beverages. Drink apple juice, gatorade/pedialyte, and water instead. Avoid alcohol and caffeine (coffee, caffeinated tea, caffeinated soda). (Note that many liquid cough medicines contain alcohol.) Food should be lukewarm, soft and bland (e.g., spaghetti/macaroni, jello, applesauce, bananas, milkshakes, yogurt, cottage cheese, baby food, oatmeal, pudding, soup, scrambled eggs, mashed potatoes). Avoid hard and rough foods like chips, crackers, granola, nuts and pretzels.
  • Try liquid supplements such as Ensure, Glucerna, Boost, and Carnation Instant Breakfast.
  • Let soda sit overnight to reduce the amount of carbonation and stir it before drinking. (Coca Cola tastes pretty bad warm and without fizz, but Dr. Pepper, Sierra Mist, and Ginger Ale actually taste pretty good.)
  • Eat popsicles, sherbet, ice cream, frozen yogurt and other chilled foods. (Note, however, that milk products may be more difficult to digest and so should be avoided if you are suffering from nausea and vomiting. On the other hand, Breyer's Mint Chocolate Chip Ice Cream and Breyer's Mint Oreo Ice Cream were among the few foods I could keep down during chemotherapy. The mint masked the metallic taste of the chemo and vomit.)
  • Drink liquids with a straw.
  • Eat food with a teaspoon instead of a tablespoon.
  • Use petroleum jelly, Vaseline, Chapstick or Blistex on your lips.
  • Don't smoke or use chewing tobacco.
  • Capsaicin Taffy may provide temporary relief.


  • Your doctor might prescribe a topical anesthetic such as lidocaine, xylocaine, Ambesol or Orajel. But be careful, as some anesthetics may interfere with your ability to swallow and the gag reflex. This can cause choking if taken before eating.
  • Avoid topical steroids, as they can increase your risk of infection.
  • Coat the blisters with a mixture of Maalox (or Mylanta or Milk of Magnesia or Sucralfate or Kaopectate) and Benadryl. This can also be used as a mouth rinse. (Your doctor can also prescribe a mixture of Maalox, Benadryl and Viscous Lidocaine. Your doctor might prescribe a mouth rinse such as nystatin, PerioGard or Peridex. Note that Peridex may stain your teeth and tastes horrible. Sucralfate and Kaopectate also taste horrible.) You should check with your doctor before using this, especially if you are suffering from diarrhea, vomiting or constipation.
  • Betadine mouthwash diluted with water (half and half) may help, but it may stain your teeth. Do not use if you are allergic to iodine.

Oral Care

Brushing your teeth helps prevent the problem from getting worse, but can also cause further pain.

  • Use a soft-bristle toothbrush when brushing your teeth. You can also substitute a foam toothbrush, cotton swab (Q-tip) or gauze. Do not use an electric toothbrush or floss.
  • Substitute a paste of baking soda and water instead of tooth paste.
  • Do not use Listerine or other store-bought mouthwash, as they contain alcohol and will irritate your mouth (burning sensation). Instead of mouthwash, rinse or gargle with a mix of 1 teaspoon baking soda in a cup or two of water, perhaps with a pinch or two of salt added. Your dentist may be able to suggest an alternative.
  • A saline mouthwash or artificial saliva can help.

Copyright © 2005-2018 by Mark Kantrowitz. All rights reserved.

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