The short answer
Cancer treatments may cause mouth, throat, and dental problems. Radiation therapy to the head and neck, some chemotherapy, and some immunotherapy can harm the mouth, throat, and lips. Problems can include changes in taste, dry mouth, mouth sores, and swallowing trouble. They are more serious when they get in the way of eating and drinking, so tell your team about pain or fever.
Cancer treatments may cause mouth, throat, and dental problems.
Radiation therapy to the head and neck, some chemotherapy, and some immunotherapy can harm the mouth, throat, and lips.
Problems may include taste changes, dry mouth, infections and mouth sores, pain, sensitivity, swallowing trouble, and tooth decay.
Mouth problems are more serious when they interfere with eating and drinking, which can lead to dehydration or malnutrition.
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This page is for people having mouth, throat, or dental problems from cancer treatment. It covers causes, common problems, when to get help, and ways to prevent and manage them.
What causes mouth and throat problems
Cancer treatments may cause mouth, throat, and dental problems. Radiation therapy to the head and neck may harm the salivary glands (which make spit) and tissues in your mouth, and may make it hard to chew and swallow safely. Some types of chemotherapy and immunotherapy can also harm cells in your mouth, throat, and lips. Drugs used to treat cancer and certain bone problems may cause mouth problems too.
What problems may occur
Mouth and throat problems may include:
- changes in taste (dysgeusia) or smell
- dry mouth (xerostomia)
- infections and mouth sores
- pain or swelling in your mouth (oral mucositis)
- sensitivity to hot or cold foods
- swallowing problems (dysphagia)
- tooth decay (cavities)
When to get help sooner
Mouth problems are more serious if they interfere with eating and drinking, because they can lead to dehydration and malnutrition.
- Call 911 or go to an emergency department if you cannot swallow your own saliva, or your mouth or throat is swelling enough to make breathing noisy or hard. Do not drive yourself.
- Call your care team right away, at any hour, if you are on chemotherapy, a stem cell transplant or CAR T, or have low white cells, and you have a temperature of 100.4°F (38°C) or higher, chills, a sore throat, new mouth sores, white patches, or any other sign of infection. A normal temperature is not a reason to wait. CDC says to call immediately for 100.4°F (38°C) or higher (CDC). If you cannot reach your team, go to the nearest emergency department.
- Call your care team the same day if soreness in your mouth, lips, or throat is bad enough that you cannot eat, drink, or sleep. If you are on chemotherapy, make it a right-away call instead.
- Tell your care team as soon as you notice any change in your mouth, such as new white patches or ulcers, pain, sensitivity, gums that bleed when you brush, or swallowing that has become harder.
NCI prints 100.5°F (38°C) as the fever number for mouth problems. Use the lower number, 100.4°F (38°C) or higher, or your team's number if it is lower. Sources word the same temperature slightly differently.
Ways to prevent mouth and dental problems
Your doctor or nurse may advise you to take these and other steps:
- Get a dental check-up before starting treatment. Visit your dentist for a cleaning and check-up, tell them about your cancer treatment, and try to complete any dental work before treatment starts.
- Check and clean your mouth daily. Check your mouth every day for sores or white spots, and tell your doctor or nurse as soon as you notice any changes. Rinse throughout the day with a solution of warm water, baking soda, and salt—ask your nurse to write down the recipe recommended for you. Gently brush your teeth, gums, and tongue after each meal and before bed using a very soft toothbrush or cotton swabs. If you are at risk of bleeding, ask whether you should floss.
Ways to manage mouth problems and taste changes
Your healthcare team may suggest these steps:
For a sore mouth or throat
- Choose foods that are soft, wet, and easy to swallow. Soften dry foods with gravy, sauce, or other liquids.
- Blend foods or make milkshakes to make swallowing easier.
- Ask about pain medicine, such as lozenges or sprays that numb your mouth.
- Avoid foods that are crunchy, salty, spicy, or sugary, and avoid alcohol.
- Don't smoke or use tobacco.
For a dry mouth
- Drink plenty of liquids, because a dry mouth can raise the risk of tooth decay and mouth infections.
- Sip water often, suck on ice chips or sugar-free hard candy, have frozen desserts, or chew sugar-free gum.
- Use a lip balm, and ask about saliva substitutes that can coat and moisten your mouth.
- Acupuncture may also help with dry mouth.
For taste changes
Food may taste different or bland.
- Try different foods to find ones that taste best. Cold foods may help.
- If red meat tastes strange, try other high-protein foods like chicken, eggs, fish, or beans.
- If foods taste metallic, switch to plastic utensils and non-metal dishes.
- Marinating foods or adding spices may improve flavor.
Sources
Common questions
What causes mouth and throat problems during cancer treatment?
Radiation therapy to the head and neck may harm the salivary glands and tissues in your mouth and make chewing and swallowing hard. Some types of chemotherapy and immunotherapy can also harm cells in your mouth, throat, and lips. Some drugs used for cancer and certain bone problems may also cause oral problems.
What kinds of mouth and throat problems may occur?
Problems may include changes in taste or smell, dry mouth, infections and mouth sores, pain or swelling in your mouth (oral mucositis), sensitivity to hot or cold foods, swallowing problems, and tooth decay.
When are mouth problems serious?
Mouth problems are more serious if they interfere with eating and drinking, because they can lead to dehydration and malnutrition. Call your doctor or nurse if you have pain in your mouth, lips, or throat that makes it hard to eat, drink, or sleep, or if you have a fever. NCI prints 100.5°F (38°C) for this. Use the lower number, 100.4°F (38°C) or higher (CDC), or your team's number if it is lower. If you are on chemotherapy, call right away, day or night, for chills, a sore throat, new mouth sores or any sign of infection, even with a normal temperature.
How can I help prevent mouth and dental problems?
Get a dental check-up before starting treatment, and try to complete any dental work first. Check and clean your mouth daily—look for sores or white spots, rinse with a warm water, baking soda, and salt solution, and gently brush your teeth, gums, and tongue with a very soft toothbrush or cotton swabs. If you are at risk of bleeding, ask whether you should floss.
What can help with a sore or dry mouth?
For a sore mouth or throat, choose foods that are soft, wet, and easy to swallow, and ask about pain medicine like lozenges or sprays. For a dry mouth, sip water often, suck on ice chips or sugar-free hard candy, use lip balm, and ask about saliva substitutes. Your healthcare team can suggest steps that fit you.
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Fever of 100.4°F (38°C) or higher during chemo, severe pain, or trouble breathing: call your cancer care team right away, day or night. Call 911 for an emergency.
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Last updated: 2026-09-29Next planned review: 2027-01-02
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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