Mouth sores can be a common side effect from lung cancer treatments like chemotherapy or, less likely, radiation therapy. Mouth sores can be painful, but there are ways to treat them. Treating mouth sores is important; the pain they cause can make it difficult to talk or swallow, which can make you eat or drink less — and potentially cause dehydration and weight loss.

What Are Mouth Sores?

Mouth sores, also called oral mucositis, are painful areas that develop in the mouth or throat. They may appear as ulcers on the lips, inside the mouth, or on the tongue. Symptoms of mouth sores can include:

• Swollen areas in the mouth, on the gums, or on the inside of the cheeks
• Mouth pain
• Pain with chewing or swallowing
• Areas of bleeding in the mouth
• Dry, cracked lips
• Reddened areas, white patches, or yellow patches on the inside of the mouth or tongue
• Dry mouth
• Sore throat or dryness

How Chemotherapy Causes Mouth Sores

Chemotherapy works by destroying rapidly dividing cells and preventing cancer cells from replicating (making more copies of themselves). Unfortunately, chemotherapy does not only affect cancer cells. It can affect healthy cells as well, like the cells that line the mouth and throat. As chemotherapy damages these cells, mouth sores develop.

The symptoms of mouth sores may start days or weeks after receiving chemotherapy. Targeted therapy for cancer can also cause mouth sores. Targeted therapy medications are more selective about the cells they attack, but a common side effect can be mouth sores.

The chemotherapy and targeted medications for lung cancer that can potentially cause mouth sores include:

• Capecitabine (Xeloda)
• Cisplatin (Platinol)
• Cytarabine (DepoCyt)
• Doxorubicin (sold as Doxil and Adriamycin)
• Etoposide (VP-16)
• Fluorouracil
• Methotrexate
• EGFR inhibitors, including erlotinib, afatinib, osimertinib, and dacomitinib

Chemotherapy’s effect on the immune system can also cause mouth sores. If a chemotherapy regimen causes a decrease in white blood cells, the body’s immune system can become weaker. This immunosuppression can make it more likely for infections in the mouth and mouth sores to develop.

Treating and Preventing Mouth Sores

Once mouth sores develop, tell your health care team so they can determine how to treat them. Ask your oncology team if there is anything that you should avoid, like using dental floss or consuming specific foods or drinks. Treatment for mouth sores usually involves minimizing pain until your mouth can begin to heal after you finish chemotherapy.

Before starting chemotherapy, it can be helpful to visit a dentist to have your teeth cleaned and your mouth inspected for infections or cavities. Ensuring good oral health before starting chemotherapy can potentially prevent mucositis. Other important prevention measures can include being proactive about oral dental health and making simple diet changes.

Taking Care of Your Mouth

To treat and help prevent mouth sores from developing during chemotherapy, try:

• Brushing your teeth frequently with a soft-bristled toothbrush and a gentle toothpaste. If a toothbrush is too painful, use a soft swab instead.
• Keeping dentures clean (if you have them) and ensuring they fit well
• Avoiding mouthwashes that contain alcohol or hydrogen peroxide
• Using a mouth rinse and gargle made with salt water or baking soda
• Sucking on ice chips before, during, and after chemotherapy infusion
• Regularly using a moisturizing lip balm
• Staying hydrated by drinking water frequently
• Checking your mouth daily for any redness or ulcers
• Avoiding smoking or using other tobacco products

Diet Changes

Simple diet changes may also help you deal with and prevent mouth sores during chemotherapy. Tips include:

• Eating soft, moist foods (mashed potatoes, oatmeal)
• Avoiding dry or hard foods (potato chips, pretzels, or crackers)
• Eating cold or frozen foods (ice pops, ice cream, or sherbet)
• Avoiding spicy or salty foods
• Avoiding foods that contain a lot of acid (citrus fruits or juices)

Medications

Prescription mouth rinses may help treat mouth sores. These mouth rinses may be called “magic mouthwash.” They can contain multiple medications to soothe the mouth and reduce inflammation.

Some topical medications that can be helpful in treating mouth sores include steroids, antibiotics, antifungals, lidocaine, antacids, and diphenhydramine (an antihistamine). Do not use any homemade treatments without first discussing them with your oncology health care team.

Pain medications may be prescribed to help manage the pain associated with mouth sores. Pain medication will not treat the sores, but it can make your mouth more comfortable while eating or drinking.

MyLungCancerTeam Members Talk About Mouth Sores

Multiple members of MyLungCancerTeam have discussed their experiences with mouth sores from cancer therapy. One member stated that they had “canker sores, but they didn’t seem different than what I usually get.”

Another member reported that “dry mouth turned into a burning mouth. Magic mouthwash tastes terrible but is giving relief.” Other members have echoed the benefits of magic mouthwash.

Being proactive about mouth sore prevention was important, many members said. One member shared that if they “didn’t stay on top of them, then they would become very painful.”

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 6,300 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Are you living with mouth sores during cancer treatment? Share your experience in the comments below, or start a conversation by posting on your Activities page.