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Medically reviewed by C.H. Weaver M.D. Medical Editor updated 5/2019

Chemotherapy- or radiation-induced damage to the cells lining the mouth, throat and gastrointestinal (GI) tract is called mucositis. This side effect of cancer treatment can significantly affect patient quality of life and may cause delays in treatment. Treatment for mucositis consists of supportive therapies, such as mouthwashes, aimed at reducing discomfort until the cells regenerate themselves and cryotherapy (ice chips) although new medications are under investigation.1-5

CancerConnect Community490 General

What causes mouth sores

Mouth sores are a common side effect of radiation and certain chemotherapy drugs. Chemotherapy and radiation kill rapidly dividing cells, a hallmark characteristic of some cancers. The GI tract, including the mouth and the throat, is made up of cells that divide rapidly. For this reason, the GI tract is particularly susceptible to damage by chemotherapy and radiation treatment. Chemotherapy- or radiation-induced damage to the cells lining the mouth, throat and gastrointestinal tract is called mucositis.

What are the signs and symptoms of mouth sores

Symptoms of mouth sores commonly occur three to ten days following your treatment with chemotherapy. You may experience a burning sensation followed by ulcers, and your mouth may appear red (inflammation) with sores (ulcerations). There may be associated discomfort and pain.

Mouth sores can make chewing and swallowing difficult, thereby interfering with your nutrition and food intake, resulting in weight loss. Your speech may also be compromised because of the soreness. Furthermore, the lining of your mouth serves to protect you against infection, so mouth sores may make you more susceptible to bacterial, fungal, or viral infections in the mouth. Ultimately, mouth sores can become severe enough that it is necessary to reduce your dosage or delay your treatment in order to allow your mouth to heal.

What treatments are more likely to cause mouth sores

Most chemotherapy drugs can cause mucositis, but this side effect is more frequent with some treatments.(list of medications at bottom of article)

Furthermore, while mouth sores can occur with any treatment for cancer, mucositis is more severe if you are treated with the following:

  • Stem cell transplants
  • Radiation for head and neck cancer
  • Combined chemotherapy and radiation therapy
  • High-dose treatment
  • Frequent dosing schedules, such as weekly chemotherapy

The technique used to administer radiation may also impact the severity and duration of mouth sores. The following radiation techniques tend to produce less severe side effects:

  • Hyperfractionated radiation involves lower doses administered more frequently, resulting in less severe side effects.
  • Intensity-modulated radiation therapy (IMRT) spares normal tissues, reducing mouth sores, while still delivering the full radiation dose or even an increased dose to the cancer.

What makes mouth sores worse

A number of factors contribute to the severity of mouth sores, including:

  • Poor oral and dental health prior to treatment
  • Kidney disease
  • Younger or older adults
  • Smoking and the use of chewing tobacco during episodes of mucositis
  • Harsh foods and alcohol
  • Concomitant disease such as diabetes or AIDS

How are mouth sores treated

The main ways to manage oral mucositis include good oral care; mouthwashes; cryotherapy (sucking on ice chips) to minimize the damage from chemotherapy drugs; Salagen®, a drug that stimulates salivary flow; and other investigational treatments.

Oral care: Good oral care, defined as frequently rinsing the mouth with saline and brushing teeth 2-3 times per day, may help prevent mouth sores.

Mouthwashes: There are several different mouthwashes in use to reduce mucositis pain from radiation and chemotherapy.

  • "Magic Mouthwash"- a mixture of diphenhydramine, lidocaine plus an antacid is used by many cancer centers and reduces oral mucositis pain when used in patients receiving radiation therapy for the treatment of head and neck cancer or those undergoing stem cell transplant.
  • Doxeipin - The tricyclic antidepressant doxepin reduces oral mucositis in patients who receive radiation for head and neck cancer. Researchers assigned 275 patients with head and neck cancer being treated with an oral mucositis pain score > 3 to be treated with doxepin mouthwash or placebo ~ 2-3 weeks after initiation of therapy. All patients were undergoing treatment with concurrent chemotherapy and radiation. Results showed those who received the mouthwash experienced an 11.7-point decrease in mucositis pain during the first 4 hours after treatment, compared an 8.7-point decrease with placebo. This is the second clinical trial showing that doxepin mouthwash relieved chemoradiotherapy-related oral mucositis pain.6,7
  • Salt and soda mouthwash has been shown to relieve mouth sores as well as medicated mouth washes, and is less expensive.2 In fact, some researchers suggest that rinsing with chlorhexidine, an antimicrobial drug used to treat gum disease, did not provide benefit, and actually increased the risk of mouth sores in chemotherapy patients.3
  • Rinsing with a mouthwash containing the ulcer drug sucralfate has produced varied results in the treatment of mouth sores. Sucralfate has been shown to reduce mouth sores, but other researchers have found salt and soda to be equally effective.

Cryotherapy (ice chips): Symptomatic relief from mouth pain can be achieved by sucking ice chips when the chemotherapy drug is most concentrated in the body. This technique, called cryotherapy, works by decreasing blood flow to the cells in the mouth, reducing exposure to the drug and decreasing the risk of developing mouth sores. Furthermore, according to a recent Cochran review, sucking ice is the only measure proven to prevent mouth sores.4

A study in the April 2019 issue of JNCCN—Journal of the National Comprehensive Cancer Network supports oral cryotherapy as a cost effective easy way to reduce mucositis related side effects.

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This current study enrolled 50 patients, half of which were provided with with ice chips to be chewed continuously during oxaliplatin chemotherapy infusions. Patients were encouraged to keep the ice chips in their mouths as long as possible. The two groups were then directly compared.

At baseline, none of the patients in either group reported any ongoing oral symptoms. After the first treatment cycle, only 32% of cryotherapy patients experienced oral symptoms, compared with 72% not chewing the ice chips. By the second cycle, the “oral cryotherapy” patients had significantly fewer oral symptoms, less difficulty eating or drinking cold items, and less difficulty eating or drinking overall than those in the control group.5

What else might work to control mucositis?

GELX ORAL GEL is a bioactive therapy that can build an effective barrier against the pain and inflammation of oral mucositis. It coats exposed nerve endings and open sores soothing oral lesions caused by chemotherapy or radiotherapy and provides a bioactive Zinc-Taurine Complex that hinders and delays the inflammatory response.15,16

Kepivance™ (keratinocyte growth factor, palifermin): Keratinocyte growth factor is a naturally produced substance that stimulates the growth of cells which are involved in protecting the lining of the mouth. Kepivance™ is produced in a laboratory and is designed to mimic natural keratinocyte growth factor that is made in the body. By stimulating growth in the cells that line the mouth and GI tract, Kepivance™ may help to reduce mucositis.

Kepivance™ is the first FDA-approved drug for the prevention and treatment of oral mucositis. In clinical trials, Kepivance™ has demonstrated the ability to protect the epithelial cells from the damaging effects of radiation and chemotherapy in patients undergoing autologous stem cell transplantation. (5-8) Research is underway to determine whether Kepivance™ may benefit other patients.

Amifostine (Ethyol®): Ethyol® is a drug that protects against the damage of radiation and is the first drug to be approved by the FDA for the treatment of patients with head and neck cancers receiving radiation therapy. Clinical trials have demonstrated that Ethyol® can reduce dry mouth and may prevent mouth sores; however, more research is needed to prove the affect of this drug on mouth sores.

Intravenous Glutamine

Among patients with advanced head and neck cancer treated with chemotherapy and radiation therapy, intravenous treatment with a derivative of the amino acid glutamine may reduce the severity of oral mucositis. These results were published in the International Journal of Radiation Oncology Biology Physics.

Glutamine is an amino acid that plays a role in cellular repair. To evaluate the safety and effectiveness of intravenous administration of a derivative of glutamine-L-alanyl-L-glutamine-researchers in Argentina conducted a clinical trial among 29 patients with advanced head and neck cancer. Half the patients received intravenous L-alanyl-L-glutamine and half the patients received intravenous saline (the placebo).

  • Severe oral mucositis developed in 14% of patients treated with L-alanyl-L-glutamine and 67% of patients treated with the placebo.
  • A feeding tube was required by 14% of patients treated with L-alanyl-L-glutamine and 60% of patients treated with the placebo.
  • Patients treated with L-alanyl-L-glutamine reported less pain than patients treated with the placebo.
  • L-alanyl-L-glutamine did not appear to produce any adverse side effects.

The researchers conclude that intravenous treatment with the glutamine derivative L-alanyl-L-glutamine may reduce the severity of oral mucositis in patients with advanced head and neck cancer.

Laser Therapy Reduces Oral Mucositis in Head and Neck Cancer

The use of low-level laser therapy (LLLT) may reduce the incidence and severity of oral mucositis caused by chemotherapy and/or radiation therapy among patients with head and neck cancer.

LLLT has been evaluated for the treatment and prevention of mucositis among patients with head and neck cancer undergoing radiation and/or chemotherapy, demonstrating potential promise for reducing severity and incidence of oral mucositis in this group of patients. The laser is directed at affected areas of the mouth and is thought to stimulate healing.

Researchers from Brazil recently conducted a Phase III trial to evaluate LLLT in reducing the incidence and severity of OM in head and neck cancer patients. This trial included 94 patients who were treated with chemotherapy and radiation therapy. One group received LLLT and the other group received a placebo (inactive substitute).

  • Severe OM occurred in 48% of the placebo group and 6% of the LLLT group.
  • Mouth sores occurred in 83% of the placebo group and 49% of the LLLT group.
  • Patients in the LLLT group experienced significantly less pain, fatigue, problems swallowing, and emotional disturbances than those in the placebo group. Importantly, not one patient in the LLLT group had a reduction or delay in treatment.

These results suggest that LLLT may reduce OM among head and neck cancer patients. Direct comparisons of LLLT to other treatments for OM are warranted.11

The chemotherapy drugs that have been reported to cause mucositis in 30% or more of patients are:

  • 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®)

The chemotherapy drugs that have been reported to cause mucositis in 10%-29% of patients are:

  • 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®)
General PMF Newsletter 490


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  2. Dodd MJ, Dibble SL, Miaskowski C, et al. Randomized clinical trial of the effectiveness of 3 commonly used mouthwashes to treat chemotherapy-induced mucositis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:39-47.
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  7. Sio TT, et al. JAMA. 2019;doi:10.1001/jama.2019.3504.
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  9. Spielberger R, Emmanouilides C, Stiff P. Use of recombinant human keratinocyte growth factor (rHuKGF) can reduce severe oral mucositis in patients (pts) with hematologic malignancies undergoing autologous peripheral blood progenitor cell transplantation (auto-PBPCT) after radiation-based conditioning – results of a phase 3 trial. Proceedings of the 39th meeting of the American Society of Oncology 2003;22: Abstract #3642.
  10. Emmanouilides C, Spielberger R, Stiff P, Rong A, et al. Palifermin Treatment of Mucositis in Transplant Patients Reduces Health Resource Use: Phase 3 Results. Proc Am Soc Hem. Blood 2003;102(11):251a, Abstract #883.
  11. Cerchietti LCA, Navigante AH, Lutteral MA et al. Double-Blinded, Placebo-controlled Trial on Intravenous L-alanyl-L-glutamine in the Incidence of Oral Mucositis Following Chemoradiotherapy in Patients with Head and Neck Cancer. International Journal of Radiation Oncology Biology Physics. 2006;65:1330-1337.
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  13. Reference: Antunes H, Herchenhorn C, Arajugo E, et al. Phase III trial of low-level laser therapy to prevent induced oral mucositis in head and neck cancer patients submitted to concurrent chemoradiation. Paper presented at: 2011 Annual Meeting of the American Society of Clinical Oncology; June 3-7, 2011; Chicago, IL. Abstract LBA5524.
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