Cancer treatments, particularly chemotherapy, head and neck radiotherapy, and some targeted therapies or immunotherapies, can cause problems affecting the mouth. Good oral care can help prevent complications, reduce discomfort and support adequate nutrition.

How Can Chemotherapy Affect the Mouth?

Chemotherapy can temporarily damage the healthy cells lining the mouth, leading to:

  • Oral mucositis (inflammation and ulceration of the lining of the mouth).
  • Mouth or throat pain.
  • Dry mouth (xerostomia).
  • Taste changes.
  • Fungal, viral or bacterial infections.
  • Bleeding gums, particularly in people with thrombocytopenia.
  • Difficulty eating, drinking or speaking.

Before starting treatment, it is advisable to undergo a dental assessment to identify and treat any existing dental or gum problems.

Oral Care During Chemotherapy

International guidelines recommend maintaining excellent oral hygiene throughout treatment.

Daily Oral Hygiene

  • Brush your teeth after every meal and before going to bed.
  • Use a soft-bristled toothbrush.
  • Use fluoride toothpaste.
  • Clean between your teeth daily if your healthcare team considers it safe.
  • Keep dentures clean and ensure they fit properly.

Recommended Mouth Rinses

Frequent rinsing may be helpful using:

  • Water.
  • Saline solution.
  • A mild bicarbonate solution prepared according to professional advice.

Alcohol-containing mouthwashes are not routinely recommended because they may irritate the oral tissues and worsen dryness.

If You Develop Pain or Mucositis

Inform your doctor or nurse if you experience:

  • Mouth ulcers.
  • Severe oral pain.
  • Difficulty eating or drinking.
  • Oral bleeding.
  • White patches or signs of infection.

Specific treatments are available and may include pain-relieving medicines, topical anaesthetics, mucosal protective agents and treatments for infections.

Dry Mouth (Xerostomia)

Reduced saliva production can cause:

  • A sensation of dry mouth.
  • Difficulty chewing or swallowing.
  • Taste alterations.
  • An increased risk of tooth decay and oral infections.

The following measures may help:

  • Drink water frequently.
  • Suck ice cubes if approved by your healthcare team.
  • Use artificial saliva or specialised oral moisturising products.
  • Chew sugar-free gum or suck sugar-free sweets when appropriate.
  • Avoid tobacco and alcohol.

Eating When You Have Mouth Problems

If your mouth is painful or sensitive:

Recommended Foods

  • Soft, moist foods.
  • Purées, soups, yoghurts and smoothies.
  • Lukewarm or cold foods.
  • Nutritional supplements if required.

Foods and Drinks to Avoid

  • Very hot foods.
  • Spicy foods.
  • Citrus fruits if they cause stinging or discomfort.
  • Hard or crunchy foods.
  • Alcoholic drinks.

If you are losing weight or struggling to eat, you may benefit from an assessment by a registered dietitian.

How Can Radiotherapy Affect the Mouth?

Radiotherapy to the head and neck may cause:

  • Oral mucositis.
  • Mouth and throat pain.
  • Dry mouth.
  • Thick or sticky saliva.
  • Taste changes.
  • Difficulty chewing or swallowing.
  • An increased risk of dental decay.

These side effects often develop gradually during treatment and improve afterwards, although some may persist in the long term.

Long-Term Effects of Radiotherapy

Some people may develop lasting side effects, including:

  • Chronic xerostomia.
  • Increased susceptibility to tooth decay.
  • Jaw stiffness (trismus).
  • Persistent taste changes.
  • An increased risk of dental complications.

For this reason, regular dental follow-up remains important even years after treatment has ended.

Oral Care During Radiotherapy

International recommendations include:

  • Maintaining meticulous oral hygiene.
  • Using a soft toothbrush.
  • Applying fluoride treatments when recommended.
  • Attending regular dental reviews.
  • Avoiding tobacco and alcohol.
  • Maintaining good hydration.

Patient education and structured oral care protocols have been shown to reduce the severity of mucositis and other oral complications.

When Should You Contact Your Healthcare Team?

Seek medical advice promptly if you experience:

  • Painful mouth ulcers.
  • Inability to eat or drink.
  • Persistent oral bleeding.
  • A fever above 38°C.
  • White patches or suspected infection.
  • Severe pain that does not improve with prescribed medication.

Significant weight loss or signs of dehydration.