Canker Sores on the Tongue: Causes, How to Treat Them, and When to See a Dentist

Why Can Canker Sores Appear on the Tongue?

A tongue canker sore is a small ulcer on the surface of the tongue that usually feels painful, sore, or burning—especially while eating, drinking, or talking. This condition is quite common and may appear in several areas, such as:

• The tip of the tongue

• The side of the tongue

• Under the tongue

Most canker sores are mild and heal on their own within 7–14 days. However, recurrent sores or ulcers that do not heal may indicate an underlying health condition that requires further evaluation.

The tongue contains many nerve endings and constantly moves during speech and chewing. Because of this, even a small ulcer on the tongue often feels more painful than canker sores in other areas of the mouth.

Types of Tongue Canker Sores (Recurrent Aphthous Stomatitis / RAS)

Minor Aphthous Ulcer

This is the most common type, accounting for approximately 80% of all canker sore cases. The ulcer is usually round or oval with a whitish-yellow center surrounded by a red inflammatory border.

Characteristics:

• Small size, usually less than 10 mm in diameter

• Typically appears as one or a few ulcers at a time

• Mild to moderate pain, especially with spicy, acidic, or salty foods

• Heals spontaneously within 7–10 days (up to 2 weeks)

• Does not leave scars after healing

Major Aphthous Ulcer

Major aphthous ulcers are larger, deeper, and more severe than minor ulcers.

Characteristics:

• Larger than 10 mm in diameter

• Intense and sharp pain

• May interfere with chewing, swallowing, and speaking

• Healing can take weeks to several months

• Often leaves scarring due to deeper tissue involvement

Although less common, this type may require additional medical evaluation if it recurs frequently, as it can be associated with systemic diseases or nutritional deficiencies.

Herpetiform Ulceration

This type is called “herpetiform” because the ulcers appear in clusters resembling herpes lesions, although they are not caused by the herpes virus and are not contagious.

Characteristics:

• Numerous tiny ulcers (1–3 mm) appearing in clusters

• Can merge into one larger irregular ulcer

• Often causes significant pain due to the wide affected area

• Usually heals within 10–14 days

• Generally does not leave scars unless the ulcers become very large and deep

The Most Common Triggers of Tongue Canker Sores

1. Minor Local Trauma

   Although canker sores are not directly caused by injury, small trauma can trigger ulcers in susceptible individuals. Common examples include:

• Accidentally biting the tongue

• Friction from sharp or broken teeth

• Irritation from braces or ill-fitting dentures

• Aggressive tooth brushing

2. Nutritional Deficiencies (Iron, Vitamin B12, Folate)

   Deficiencies in essential nutrients may impair tissue regeneration and weaken the oral mucosa, making the tongue more vulnerable to ulcer formation. Common deficiencies associated with recurrent canker sores include:

• Vitamin B12 deficiency

• Iron deficiency

• Folate (Vitamin B9) deficiency

  Patients with frequent or multiple ulcers may require further evaluation for hidden nutritional deficiencies or digestive absorption disorders.

3. Psychological Stress and Immune Changes

   Canker sores are considered immune-mediated conditions. Stress, lack of sleep, and fatigue can weaken the local immune system in the mouth, increasing the risk of inflammation.

   These ulcers commonly appear during:

• Sleep deprivation or excessive late nights

• Emotional stress or heavy workloads

• Recovery after illness when immunity is lower

4. Toothpaste Sensitivity and Food Irritants

   Certain environmental factors inside the mouth may worsen or trigger ulcers:

   1. Toothpaste Ingredients (SLS):
      Some toothpaste products containing Sodium Lauryl Sulfate (SLS) may irritate the oral tissues and increase ulcer susceptibility.

   2. Food Irritants:
      Very spicy, acidic, or rough-textured foods can irritate the tongue and worsen discomfort.

How to Treat Tongue Canker Sores at Home

Most mild canker sores improve with simple home care.

1. Maintain Good Oral Hygiene

   Brush gently and keep the mouth clean without scrubbing the sore aggressively. Good oral hygiene helps prevent secondary infection and further irritation.

2. Avoid Irritating Foods

   While healing, try to reduce:

   1. Spicy foods

   2. Very hot foods

   3. Acidic foods

   4. Sharp or crunchy snacks

   These foods may worsen the pain.

3. Drink Plenty of Water

   A dry mouth may slow healing. Staying hydrated helps support the natural recovery process.

4. Use Mouthwash as Recommended

   In some cases, dentists may recommend a specific mouthwash to reduce irritation and maintain oral hygiene. Always follow professional instructions before using medicated products.

5. Get Enough Rest

   Because stress and immunity play important roles, adequate sleep and balanced nutrition may help speed up healing.

Tongue Canker Sores That Should Not Be Ignored

Most canker sores are harmless. However, certain signs may indicate a more serious condition.

This table is not intended for self-diagnosis but may help identify when professional dental evaluation is necessary.

When Should You Visit a Dentist?

Many people delay treatment because they assume canker sores are “just minor ulcers.”

However, dentists are often the first healthcare professionals to detect abnormal soft tissue changes inside the mouth.

Seek professional evaluation if:

• The ulcers recur frequently

• The sore always appears in the same location

• Pain significantly interferes with eating or speaking

• The sore does not heal after 2 weeks

At Onyx Dental Center, recurrent oral ulcer evaluations can help rule out more serious conditions. Dentists perform a comprehensive examination of the tongue, gums, cheeks, and other oral tissues that may be difficult to assess at home.

Conclusion

Tongue canker sores are common oral lesions that may be triggered by minor trauma, stress, nutritional deficiencies, or irritation from certain foods. Most ulcers heal on their own within 1–2 weeks with proper home care.

However, recurrent sores, ulcers lasting longer than two weeks, or sores accompanied by other tissue changes should be evaluated by a dentist.

Early detection is important to ensure there are no underlying serious conditions. Routine oral examinations also help maintain long-term oral health before problems become more advanced.

References

1. Gasmi Benahmed, A., Noor, S., Menzel, A., & Gasmi, A. (2021). Oral Aphthous: Pathophysiology, Clinical Aspects and Medical Treatment. Archives of Razi Institute, 76(5), 1155–1163. https://doi.org/10.22092/ari.2021.356055.1767 

2. Plewa, M. C., & Chatterjee, K. (2023, November 13). Recurrent aphthous stomatitis. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK431059/ 

3. Surachmin, A., Fathia Sabila, Ahmad Ronal, & Nurfianti. (2024). Management of stomatitis apthous recurrent in patients with multiple systemic diseases - case report. YARSI Dental Journal, 1(2), 104–113. https://doi.org/10.33476/ydj.v1i2.150