What are the causes and treatments of recurrent aphthous ulcers (canker sores)?

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From the Guidelines

For recurrent aphthous ulcers, I strongly recommend using topical measures such as steroids as the first line of treatment, as evidenced by the most recent guidelines 1. The treatment of recurrent aphthous ulcers, also known as canker sores, should prioritize reducing symptoms and improving quality of life.

Causes of Recurrent Aphthous Ulcers

The exact cause of recurrent aphthous ulcers is often unknown, but they can be triggered by various factors including:

  • Stress
  • Trauma to the mouth
  • Certain foods
  • Vitamin deficiencies
  • Autoimmune disorders such as Behçet's disease

Treatment of Recurrent Aphthous Ulcers

Topical steroids should be used for the treatment of oral and genital ulcers, as recommended by the 2018 update of the EULAR recommendations for the management of Behçet's syndrome 1. Other treatment options include:

  • Colchicine for the prevention of recurrent mucocutaneous lesions, especially when the dominant lesion is erythema nodosum or genital ulcer 1
  • Azathioprine, thalidomide, interferon-alpha, TNF-alpha inhibitors, or apremilast for selected cases 1
  • Topical or systemic measures as used in acne vulgaris for papulopustular or acne-like lesions 1
  • Sucralfate suspension, which was shown to be effective for oral and genital ulcers in an RCT 1

Prevention of Recurrent Aphthous Ulcers

Prevention strategies include:

  • Using a soft-bristled toothbrush
  • Avoiding SLS-containing toothpastes
  • Identifying and eliminating trigger foods like acidic or spicy items
  • Daily supplements such as vitamin B12, lysine, and zinc
  • Stress reduction techniques, as stress is a common trigger

It is essential to consult a healthcare provider if canker sores are extremely frequent, large, or last longer than two weeks, as this could indicate an underlying condition requiring different treatment approaches.

From the Research

Causes of Recurrent Aphthous Ulcers

  • The exact cause of recurrent aphthous ulcers (RAU) is idiopathic in most patients 2
  • Possible precipitating factors include local trauma and stress 2
  • Other associated factors include systemic diseases and nutritional deficiencies, food allergies, genetic predisposition, immune disorders, the use of certain medications, and HIV infection 2
  • There is a genetic predisposition, with strong associations with interleukin genotypes, and sometimes a family history 3

Treatment Options for Recurrent Aphthous Ulcers

  • Topical medications, such as antimicrobial mouthwashes and topical corticosteroids, can achieve the primary goals of relief of pain, reduction of ulcer duration, and restoration of normal oral function 2
  • Topical treatments include antiseptics (chlorhexidine, lidocaine), anti-inflammatory drugs (amlexanox), antibiotics (tetracyclines, doxycycline), and corticosteroids (triamcinolone acetonide) 4, 5
  • Systemic medications, such as levamisole, oral corticosteroids, and thalidomide, can be tried if topical therapy is ineffective 2
  • Systemic treatments include corticosteroids (prednisone), immunomodulatory drugs (thalidomide), and antibiotics/antimicrobials (clofazimine) 4, 5

Management of Recurrent Aphthous Ulcers

  • Management should be based on identification and control of the possible predisposing factors, with the exclusion of possible underlying systemic causes, and the use of a detailed clinical history along with complementary procedures such as laboratory tests, where required 5
  • Treatment should be patient-specific and focus on reduction of pain and lesions 6
  • The primary goals of therapy for RAU are relief of pain, reduction of ulcer duration, and restoration of normal oral function, while secondary goals include reduction in the frequency and severity of recurrences and maintenance of remission 2

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Treatment strategies for recurrent oral aphthous ulcers.

American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists, 2001

Research

Oral mucosal disease: recurrent aphthous stomatitis.

The British journal of oral & maxillofacial surgery, 2008

Research

Treatment of recurrent aphthous stomatitis. A literature review.

Journal of clinical and experimental dentistry, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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