Mouth ulcers (also called aphthous ulcers) are small, shallow sores that develop on the inside of the cheeks, lips, tongue or soft palate. They typically appear white or yellow with a red, inflamed border and can be painful for 3–4 days, usually resolving within 7–10 days.

While occasional ulcers are common, frequent or persistent outbreaks often indicate an underlying imbalance — particularly involving immunity, nutrient status, stress levels or digestive health.

What Causes Mouth Ulcers?

Mouth ulcers are rarely caused by just one factor. Instead, they tend to develop when the body is under stress or the mucosal lining becomes vulnerable.

1. Nutrient Deficiencies

Deficiencies are one of the most overlooked drivers of recurrent ulcers, particularly:

• Vitamin B12
• Folate
• Vitamin B6
• Iron
• Zinc
• Occasionally lysine

These nutrients are essential for maintaining healthy mucous membranes and supporting tissue repair.

2. Digestive Imbalance

The mouth is the beginning of the digestive tract, and inflammation here often reflects dysfunction further down. Contributing factors may include:

• Low stomach acid
• Gut dysbiosis (imbalanced microbiome)
• Candida overgrowth
• Food intolerances (including gluten sensitivity or coeliac disease)
• Sluggish bowel function

When digestion is impaired, inflammatory by-products and nutrient malabsorption can increase ulcer susceptibility.

3. Stress & Immune Dysregulation

Chronic stress suppresses immune resilience and increases inflammatory signalling. Many people notice ulcers appear during periods of high emotional strain, fatigue or hormonal change.

4. Irritants & Medications

• Toothpaste containing Sodium Lauryl Sulfate (SLS)
• Certain antibiotics (e.g. sulfonamides)
• NSAIDs
• Accidental cheek biting or dental friction
• Poor oral hygiene
• Switching to an SLS-free toothpaste alone can reduce recurrence in some individuals.

5. Dietary Triggers

Highly processed, high-sugar and inflammatory diets may increase risk. Alcohol, excessive coffee and acidic or spicy foods can worsen discomfort once an ulcer forms.

Traditional Medicine Perspective

In Traditional Chinese Medicine, mouth ulcers are often associated with “heat,” particularly Liver or Stomach heat. Clinically, this often correlates with inflammatory digestive states, stress overload and dietary excess.

Dietary Strategies to Support Healing

Reduce Irritating & Inflammatory Foods

• Alcohol
• Refined sugar
• Soft drinks
• Highly processed foods
• Excess coffee
• Foods you know you react to

Emphasise Whole, Nutrient-Dense Foods

• Leafy greens
• Steamed vegetables
• Whole grains (brown rice, quinoa)
• Nuts and seeds
• Lean protein
• Adequate hydration
• Cooling foods such as cucumber, watermelon, pears and yoghurt may soothe irritated tissues if tolerated.
• A warm drink of diluted lemon with quality Manuka honey may provide mild antimicrobial support while encouraging hydration.

Natural Remedies

Topical Support

• Manuka honey – promotes wound healing and reduces microbial load
• Slippery elm paste – coats and protects mucous membranes
• Aloe vera gel – cooling and anti-inflammatory
• Chamomile mouth rinse – soothing and antimicrobial
• Calendula rinse – supports tissue repair

Nutritional & Supplemental Support

• Activated B complex (especially if deficiency is suspected)
• Zinc for tissue repair
• Iron (if low ferritin is present)
• L-glutamine to support mucosal healing
• Probiotics to restore oral and gut microbial balance
• Cod liver oil (vitamins A & D) for mucosal integrity
• Digestive enzymes may help if symptoms of bloating, heaviness or incomplete digestion are present.

Herbal Support

Traditionally used herbs that may reduce recurrence include:

• Calendula
• Chamomile
• Licorice (DGL form for mucosal repair)
• Propolis
• Echinacea
• Neem
• Aloe vera

Lifestyle Considerations

• Manage stress proactively
• Prioritise sleep
• Maintain gentle but consistent oral hygiene
• Address constipation or sluggish digestion
• Avoid SLS-containing toothpasteWhen to Seek Further Investigation

Consult your healthcare practitioner if:

• Ulcers last longer than two weeks
• They are unusually large or severe
• They occur very frequently
• You experience fatigue, weight loss or digestive symptoms

Persistent ulcers may occasionally be associated with autoimmune conditions, inflammatory bowel disease or significant nutrient deficiency.

Mouth ulcers are often a sign that the body needs additional support — particularly in digestion, stress management or nutrient replenishment. Addressing the root cause rather than just the symptom can significantly reduce both severity and recurrence.