Many people starting chemotherapy are warned about nausea and tiredness but are surprised when their mouth becomes red, raw and ulcerated a few days into a cycle. This is oral mucositis, and for some it makes eating, drinking and even talking hard work. It cannot always be prevented, but preparation before treatment and careful daily habits during it can make it less likely and less severe.
What follows is general information to use alongside the advice of your oncology team, never instead of it.
Why chemotherapy affects the lining of the mouth
Many chemotherapy drugs work by attacking cells that divide quickly. Cancer cells do, but so do the cells that keep replacing the thin lining of your mouth. When that renewal is interrupted, the lining thins and breaks down. Soreness and redness come first, and ulcers can follow. Because the lining recovers when the drugs ease off, mucositis often improves between cycles, then returns with the next one.
The same breakdown leaves the mouth more open to infection at a time when chemotherapy may also have lowered the body's defences. That is why both the dental check before treatment and the warning signs later on matter.
A dental visit before the first cycle
If your treatment timeline allows it, see your dentist before chemotherapy starts. The aim is to find and settle anything that could flare up during treatment: decay close to a nerve, a broken tooth with a sharp edge, gum infection, or a wisdom tooth that has caused trouble before. Treating these while your immune system is working normally is far easier than dealing with an emergency when your blood counts are low.
Tell your dentist which drugs you will be having and give them your oncology team's contact details. Some cancer treatments include medicines that affect the jawbone, and planning around those is discussed in our guide to bone medications and the jaw.
Cold in the mouth during certain infusions
Sucking ice chips or holding ice water in the mouth during an infusion is called oral cryotherapy. The cold narrows the small blood vessels in the lining, so less of the drug reaches it while levels in the blood are highest.
The evidence is strongest for particular regimens. A Cochrane review (Riley and colleagues, 2015) found moderate quality evidence that oral cryotherapy probably reduces mucositis in adults having fluorouracil-based chemotherapy, with the risk of mucositis of any severity cut by about 40 percent, and that it may help adults having certain high-dose chemotherapy before a stem cell transplant. Side effects were minor, such as headache, chills or tooth pain. The review found little evidence for other chemotherapy types and none for children. Because cryotherapy only suits short infusions of certain drugs, ask your oncology team whether it fits your plan before trying it.
Keeping the mouth clean without hurting it
Daily care during chemotherapy has two jobs: keep bacteria down and avoid injuring tissue that is already fragile.
- Brush twice a day with a soft or extra-soft toothbrush and a mild fluoride toothpaste. If even a soft brush hurts, soak it in warm water first.
- Rinse often through the day with plain water or a bland salt and bicarbonate soda rinse. Ask your treating team for the recipe they prefer.
- Skip mouthwashes containing alcohol, which can sting and dry the mouth.
- Keep your lips moist with a plain balm.
- Take dentures out at night and when the gums are sore, and keep them clean.
- Avoid tobacco and alcohol, both of which irritate the lining.
A dry mouth makes mucositis worse, since saliva protects and lubricates the lining. Our article on dry mouth has practical suggestions. A white coating that wipes off, or new burning soreness, may point to thrush, which is more common when immunity is low; the signs are described in our guide to oral thrush in adults.
Eating when your mouth is sore
Soft, moist, mild food is easiest. Smooth soups that have cooled a little, yoghurt, scrambled eggs, porridge, mashed vegetables and soft fish are usually better tolerated than anything crunchy, salty, spicy or acidic. Cool or room-temperature food tends to sting less than hot food, and a straw can help liquids bypass the sorest areas.
Pain relief is part of good care, not a sign of giving in. Your team can recommend or prescribe suitable options, including coating or numbing rinses. If you are eating or drinking much less than usual, tell them early, because dehydration and weight loss can affect your treatment.
Signs that need a call to your treating team
- Pain that your current relief does not control
- Not being able to drink enough to stay hydrated
- A temperature or fever
- Bleeding in the mouth that does not stop
- White patches, pus or swelling that suggest infection
During chemotherapy, a fever can be serious, so follow the instructions your oncology unit has given you about when to call. Separately, any ulcer or patch that has not healed or changed within three weeks, or that persists well after a cycle has ended, should be looked at by your dentist or doctor, as explained in our article on oral health checks.
Common questions
Should I keep brushing if my mouth is sore?
Yes, gently. A clean mouth is less likely to become infected. Use the softest brush you can find and a mild toothpaste, and lean on rinses if brushing a particular area is too painful for a day or two.
Will mucositis go away?
For most people it settles as the lining recovers after each cycle and once treatment finishes. How long that takes varies with the drugs and doses involved.
Can I see a dentist during chemotherapy?
Often yes, but timing matters because blood counts change through each cycle. Your dentist will usually check with your oncology team before doing any treatment.
Sources
If you would like a dental check before or during cancer treatment, the team at Lumi Dental in Melrose Park can coordinate with your oncology team. Please follow your treating doctors' advice at every stage.
