Mouth sores can have various causes, including canker sores, infections and pressure ulcers due to dentures. One common cause is cancer treatment: It can attack the mucous membranes or weaken the immune system so much that germs spread and lead to inflammations.
Depending on what the cause is, it's treated in different ways. For example, antimycotics (antifungal drugs) are a suitable treatment for a fungal infection. There aren’t always special medications that can get rid of the underlying cause, though. Then you can use gels or rinses from the pharmacy that relieve or slightly numb the pain.
If you would prefer not to use medication, you can try to protect the lining of your mouth when you eat and drink.
To keep from irritating inflamed parts of your mouth more, and to prevent them from getting worse or new sores from forming, it’s better to avoid the following foods and drinks until the wounds have healed:
When you chew, the mucous membranes lining your mouth move. This stretches the sore areas, which can hurt. Eating soups or soft food can help to prevent this pain.
During cancer treatment, people may have inflammations in their mouth as well as nausea, loss of appetite or loss of taste. As a result, they may eat less and lose too much weight. Adding things like butter or cream to soups and puréed food may help. This keeps the meals easy to eat and ensures that you have more calories even when you eat smaller portions. The higher fat content also enhances the taste of the food, making it easier to avoid using a lot of spices.
It is also important to let cooked food cool down enough before you eat – or to simply eat cold meals. These include mild quark and yogurt dishes, shakes, smoothies, and cold soups – such as soups made with buttermilk, cucumber, or tomatoes.
Thorough oral and dental hygiene is important – not only to prevent inflammations in the mouth, but also when mouth sores have already developed. It includes the following:
It is possible to increase saliva production, for example, by chewing sugar-free gum. It is also be a good idea to wear dentures less often until the inflammation goes away, and it's important to clean them carefully.
It is also important to drink enough fluids, not smoke and regularly check the lining of your mouth in the mirror. If the pain gets worse, or if the mucous membranes swell, change color or bleed heavily, it's a good idea to see a doctor or dentist.
Deutsches Krebsforschungszentrum (DKFZ), Krebsinformationsdienst (KID). Schleimhautentzündung bei Krebs: Vorbeugen und lindern. 2022.
Deutsches Krebsforschungszentrum (DKFZ), Krebsinformationsdienst (KID). Zahnpflege und Mundhygiene. 2022.
Leitlinienprogramm Onkologie (Deutsche Krebsgesellschaft DK, AWMF). Supportive Therapie bei onkologischen PatientInnen. 2025.
Peterson DE, Boers-Doets CB, Bensadoun RJ et al. Management of oral and gastrointestinal mucosal injury: ESMO Clinical Practice Guidelines for diagnosis, treatment, and follow-up. Ann Oncol 2015; 26 (Suppl 5): v139-151.
IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.
Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.
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