Almost everyone has experienced canker sores. The pain and discomfort when eating or speaking makes canker sores very disruptive to daily activities. But did you know that not all mouth ulcers are canker sores?

What Are Canker Sores?

Canker sores or Recurrent Aphthous Stomatitis (RAS) are ulcers in the oral cavity that recur at least 3-4 times a year, have no known definite cause, and heal on their own. RAS is a painful but very common oral condition.

Types of Canker Sores

TypeSizeCommon LocationHealing TimeScarring
Minor RAS< 10 mmLips, cheeks, floor of mouth10-14 daysNo
Major RAS> 1 cmLips, soft palate, tongue, gums~6 weeksYes
Herpetiform RASSmall but numerous (up to 100)Can appear anywhere10-14 daysNo

Minor RAS

The most common type of canker sore. Less than 10 mm in size and usually appears on the lip mucosa, cheeks, and floor of the mouth. Heals in 10-14 days without leaving scars.

Major RAS

Accounts for about 10-15% of all canker sore cases. Larger than 1 cm and very painful. Often affects the lips, soft palate, tongue, and gums. Heals in about 6 weeks and may leave scars.

Herpetiform RAS

Characterized by small ulcers that appear in large numbers, sometimes up to 100. These small ulcers can merge into larger ones. Heals in 10-14 days.

Important: Despite the name “herpetiform,” this type of canker sore is not caused by the herpes virus.

Triggering Factors for Canker Sores

Although the exact cause of canker sores is unknown, the following factors can trigger them:

  • Genetics — If parents frequently get canker sores, children tend to experience them too
  • Trauma — Accidental biting, toothbrush friction, or injury from hard food
  • Nutritional deficiency — Iron, vitamin B12, and folic acid deficiency
  • Stress — Physical or emotional pressure
  • Hormonal changes — Especially in women during menstruation or pregnancy
  • Allergies — Reactions to certain foods or materials
  • Medications — Side effects of certain drugs
  • Infections — Bacteria and viruses
  • Tobacco — Use of tobacco products

How to Treat Canker Sores

Canker sores can heal on their own even without treatment. However, to reduce pain and speed up healing:

Treatment

  • Anti-inflammatory medication or pain-relieving gel applied to the ulcer
  • Antiseptic mouthwash to prevent secondary infection
  • Treatment tailored to triggering factors — for example, if triggered by iron deficiency, the doctor will recommend iron supplements

Prevention

  • Maintain oral hygiene — Brush teeth twice a day with a soft-bristled brush
  • Avoid trauma — Be careful when chewing, avoid hard foods that could injure the mouth
  • Meet nutritional needs — Ensure adequate iron, vitamin B12, and folic acid intake
  • Manage stress — Excessive stress can trigger canker sores
  • Avoid trigger foods — Identify and avoid foods that cause frequent canker sores (such as acidic or spicy foods)

Warning Signs: When to See a Doctor

Not all mouth ulcers are canker sores. See a dentist immediately if:

  • The ulcer doesn’t heal for more than 2 weeks
  • The ulcer keeps getting larger
  • There are hard raised edges around the ulcer
  • Canker sores appear very frequently and are getting worse
  • Accompanied by fever or other systemic symptoms

Mouth ulcers that don’t heal could be a sign of a more serious condition. For an accurate diagnosis and proper treatment, visit your dentist.

Conclusion

Canker sores are a very common and usually non-dangerous condition. Although painful, canker sores generally heal on their own within 1-2 weeks. The key is to maintain oral hygiene, meet nutritional needs, and manage stress to reduce their frequency.

However, stay alert to unusual mouth ulcers. When in doubt, always consult a dentist for proper treatment.