Aphthous Ulcers: Causes, Types, and Treatments

Aphthous ulcers (oral aphthous), commonly known as canker sores, present a prevalent oral concern affecting 20-25% of the population. Unlike fever blisters (cold sores), aphthous ulcers are painful white or yellow sores that emerge inside the mouth and are not contagious. Oral apotheosis is a painful inflammatory process of the oral mucosa. If recurrence occurs frequently, the condition is recurrent aphthous stomatitis RAS. Stressful life events are significantly associated with the onset of RAS episodes, nearly tripling the odds of occurrence (Verma et al., 2023). 

Who is affected?

According to retrospective population-based studies in different countries and regions, the prevalence can range from 1.4% to 21.4%. (Liu et al., 2022).  Recurrent aphthous stomatitis is a chronic inflammatory disease of the oral mucosa. It is characterized by painful mouth ulcers that an underlying disease cannot explain (Sanchez, et al., 2020) and may be present first in childhood or adolescence and affect up to 25% of the general population and 3-month recurrence rates are as high as 50%, and are more common in females ulcers can appear alone or secondary to distinct disease processes. (Gasmi et al., 2021). The pathophysiology of oral aphthous ulcers remains unclear, but various bacteria are part of its microbiology (or cause the lesions to develop). Aphthous ulcers do not have a known cause, and an injury, stress, smoking, or deficiencies in folic acid, iron, or vitamin B12 may trigger this type of oral lesion. According to retrospective population-based studies in different countries and regions, the prevalence can range from 1.4% to 21.4%. (Liu et al., 2022).

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What are clinical manifestations?

The clinical manifestation of aphthous ulcers includes the presence of persistent, painful oral ulcers lasting days to months. Oral lesions, a characteristic feature of recurrent aphthous stomatitis, can occur on the tongue, inner cheeks, gums, or throat (Pleawa & Chatterjee., 2023)

What are the different types of aphthous ulcers?

  1. Minor Aphthous Ulcers: The most common form, affecting around 80% of patients. They are small, oval, or round, usually less than 5 mm in diameter, and recur at 1 to 4-month intervals- they can appear as a group of 1 to 6 ulcers at a time, surrounded by an erythematous halo, and heal within two weeks without scarring.
  2. Major Aphthous Ulcers: This is a more severe form in 10% of patients. The ulcers are larger (>10 mm), last for 5 to 10 weeks, and may leave scarring. Any area of the mouth can be affected, including the oropharynx.
  3. Herpetiform Ulcers: The least common type, affecting around 1% to 10% of patients. These ulcers resemble primary herpetic stomatitis, although there is no connection to herpes viruses. They appear as painful, small, and numerous ulcers, sometimes reaching up to 100 at one time, measuring 2 to 3 mm in diameter, and lasting one to two weeks. They may appear as irregular ulcers that heal with scarring.

Figure 1. Herpetiform ulcers on the right upper facial gingiva (A). Major aphthous ulcers on the right side of the lateral tongue and lingual frenum.

What are treatment options?

The treatment primarily focuses on relieving pain and promoting lesion healing, such as:

  • Glucocorticoids (steroids) like dexamethasone 0.5mg/5ml rinse, fluocinonide 0.05% gel/ointment, and triamcinolone 0.1% gel/ointment.
  • Laser therapy stands out for its efficiency, harnessing anti-inflammatory and pro-repair effects, all achieved without inducing thermal damage. Low-Level Laser Therapy (LLLT) exhibits exceptional effectiveness in promoting healing, reducing size, and alleviating symptoms for short-term ulcer flare-ups (Liu,2022).
  • Probiotics, essential parts of the natural bacteria in the mouth, show promise as a long-term solution. Even if early trials don’t immediately reveal benefits, using probiotics as mouthwash or tablets helps in long-term healing. Probiotics’ competitive effects and microenvironment control are valuable for extending the time between episodes and reducing recurrence. Their signaling molecules have pro-repair effects that help reduce the level of pro-inflammatory (Sánchez-Bernal & Conejero, 2021).

How do social factors affect aphthous ulcers?

Stressful life events are significantly associated with the onset of recurrent aphthous stomatitis (RAS) episodes, nearly tripling the odds of occurrence, highlighting the profound impact of psychosocial factors (psychological and social factors) or social determinants that affect health.

Within underserved populations contending with socioeconomic hardships such as poverty, food insecurity, and strenuous working conditions, RAS prevalence might be markedly higher. For dentists serving in underserved communities, recognizing these social determinants of health becomes pivotal, urging a tailored, multicultural approach in health education to address the dynamic health concerns among diverse populations and the burden of RAS.

Health communication is essential in raising awareness and promoting understanding of oral lesions, specifically aphthous ulcers. Effective health communication strategies must consider individuals’ and communities’ health literacy (more than the ability to read) and minimize confusing and overwhelming health jargon; public awareness campaigns, social media, and pamphlets in healthcare settings should consider the best practices for target populations. Health communication educates people on understanding the early signs of these common oral lesions, seeking medical attention, reducing discomfort, and helping make informed decisions. For this reason, effective health communication is essential for people to understand, prevent, and manage common oral lesions, particularly aphthous ulcers.

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Like what you’re learning? Consider enrolling in the Herman Ostrow School of Dentistry of USC’s online, competency-based certificate or master’s program in Community Oral Health.


  • Bensley, R. & Brookins-Fisher, J. (2019). Community Public Health Education Methods: A Practical Guide (4th ed.). Jones & Bartlett Learning.  
  • 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. doi: 10.22092/ari.2021.356055.1767Huling, L. B.
  • Baccaglini, L., Choquette, L., Feinn, R. S., & Lalla, R. V. (2012). Effect of stressful life events on the onset and duration of recurrent aphthous stomatitis. Journal of oral pathology & medicine : official publication of the International Association of Oral Pathologists and the American Academy of Oral Pathology, 41(2), 149–152 https://doi.org/10.1111/j.1600-0714.2011.01102.x
  • Liu H, Tan L, Fu G, Chen L, Tan H. Efficacy of Topical Intervention for Recurrent Aphthous Stomatitis: A Network Meta-Analysis. Medicina (Kaunas). 2022 Jun 7;58(6):771. doi: 10.3390/medicina58060771. PMID: 
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  • Verma S, Srikrishna K, Srishti, Shalini K, Sinha G, Srivastava P. Recurrent Oral Ulcers and Its Association With Stress Among Dental Students in the Northeast Indian Population: A Cross-Sectional Questionnaire-Based Survey. Cureus. 2023 Feb 13;15(2):e34947. doi: 10.7759/cureus.34947. PMID: 36939443; PMCID: PMC10019935.


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