Are aphthous ulcers (canker sores) caused by viruses?

From the Guidelines

No, aphthous ulcers (canker sores) are not caused by viruses. These painful mouth sores result from an inflammatory process rather than a viral infection. The exact cause remains unclear, but several factors can trigger them, including minor mouth injuries, food sensitivities (particularly to chocolate, coffee, strawberries, eggs, nuts, cheese, and spicy or acidic foods), hormonal changes, emotional stress, and certain nutritional deficiencies (especially iron, zinc, folate, and vitamins B-12 and B-6) 1.

Key Points to Consider

• Treatment typically involves over-the-counter topical products containing benzocaine, hydrogen peroxide, or fluocinonide to reduce pain and inflammation.
• For relief, patients can rinse with salt water (1/2 teaspoon salt in 1 cup warm water) or use antimicrobial mouthwashes.
• Most canker sores heal on their own within 1-2 weeks without treatment.
• However, if sores are unusually large, persistent (lasting more than 3 weeks), extremely painful, or accompanied by fever, patients should seek medical attention as these could indicate a more serious condition.

Relevant Evidence

The provided studies do not directly address the cause of aphthous ulcers, but they do discuss various other medical conditions and their management. For example, the study on herpes labialis 1 discusses the management of recurrent episodes of herpes labialis, which is a different condition from aphthous ulcers. Another study 1 discusses the management of inflammatory bowel disease, which is also unrelated to the cause of aphthous ulcers. However, a study on gynecologic examination for adolescents 1 mentions aphthous spectrum ulcers as a possible finding, but does not discuss their cause.

Clinical Implications

In clinical practice, it is essential to differentiate aphthous ulcers from other conditions, such as herpes simplex virus (HSV) or syphilis, which can cause similar symptoms 1. A thorough medical history, physical examination, and laboratory tests can help diagnose the underlying cause of mouth sores. Treatment should focus on reducing pain and inflammation, and preventing complications. Patients with persistent or severe symptoms should be referred to a specialist for further evaluation and management.

From the Research

Causes of Mouth Aphthae

• The exact causes of mouth aphthae, also known as aphthous ulcers or canker sores, are not entirely clear 2, 3, 4.
• Various factors are thought to contribute to the development of aphthous ulcers, including:
  • Local physical trauma 5
  • Genetic predisposition 3
  • Interleukin genotypes 3
  • Family history 3
  • Stress 4
  • Hormonal state 4
  • Food hypersensitivity 4
  • Infectious or immunologic factors 4
• Systemic conditions, such as Behçet's disease, human immunodeficiency virus (HIV) disease, and gastrointestinal diseases, can also be associated with aphthous-like ulcers 4, 6.

Role of Viruses

• There is no clear evidence to suggest that viruses are a primary cause of aphthous ulcers 2, 3, 4, 6, 5.
• However, it is noted that aphthae themselves are often mistaken for recrudescent oral herpes simplex virus (HSV) infections 6.
• The exact relationship between viruses and aphthous ulcers is not well understood and requires further research.