What are the causes of oral lesions?

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Last updated: May 19, 2025View editorial policy

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From the Guidelines

Oral lesions that persist for more than two weeks should be evaluated by a dentist or doctor, as they can be indicative of various conditions ranging from minor irritation to serious diseases like oral cancer. The diagnosis of oral lesions can be challenging due to their diversity and complexity, and a comprehensive assessment is often needed 1. According to the expert consensus guideline for diagnosis, a biopsy should be considered for oral ulceration that cannot be diagnosed after collection of clinical medical history and oral examination, especially those with a course over 2 weeks, or cases that do not respond to 1-2 weeks of treatment 1.

Diagnostic Approach

The diagnostic work-up for difficult and complicated oral ulcers should include a detailed clinical medical history inquiry, histopathological examination, and screening for ulceration-related systemic diseases 1. Blood tests, such as full blood count, coagulation, fasting blood glucose level, HIV antibody, and syphilis serology examination, are necessary to exclude contraindications and provide clues for further clinical examination and diagnosis 1.

Treatment

Common oral lesions, such as canker sores (aphthous ulcers), can be treated with over-the-counter topical medications like benzocaine (Orajel) or prescription options like triamcinolone dental paste applied 2-3 times daily 1. Cold sores caused by herpes simplex virus may benefit from antiviral medications like acyclovir (400mg three times daily for 5-7 days) or valacyclovir (1g twice daily for 7-10 days) 1. For fungal infections like oral thrush, nystatin oral suspension (swish and swallow 4-5 times daily) or fluconazole (200mg on day one, then 100mg daily for 7-14 days) are effective treatments 1.

Prevention

To promote healing and prevent further irritation, it is essential to avoid spicy foods, alcohol, and tobacco products, and maintain good oral hygiene by brushing twice daily and flossing 1. Prompt evaluation of unexplained or persistent lesions is crucial, as oral lesions can indicate various conditions ranging from minor irritation to serious diseases like oral cancer 1.

From the Research

Types of Oral Lesions

  • Oral lesions may be single or multiple and can arise from various causes such as infectious, immune, congenital, medication use, or idiopathic causes 2
  • Common oral lesions include ulcerated lesions, white or mixed white-red lesions, lumps and bumps, and pigmented lesions 3
  • Lesions of the mouth can range from innocuous to highly malignant neoplasms, requiring a clear and concise history, thorough clinical examination, and possibly radiographs and laboratory investigations for diagnosis 4

Causes of Oral Lesions

  • Herpes simplex virus (HSV) and varicella zoster virus (VZV) can cause oral lesions, with HSV-1 and HSV-2 resulting in oral and genital lesions 5
  • Human papillomavirus (HPV) can also cause oral lesions, with different subtypes resulting in various benign lesions 5

Treatment of Oral Lesions

  • Acyclovir and other nucleoside analogues have been the standard treatment for HSV and VZV, but newer treatments are being developed to address resistance to standard antivirals 5
  • Local anesthetics such as lidocaine and prilocaine have shown antiviral properties and can be used to decrease pain caused by oral lesions 6
  • Topical treatments with well-elucidated drugs, such as semi-solid film-forming formulations, have been developed and evaluated for the treatment of oral lesions caused by HSV-1 6

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Acute Oral Lesions.

Dermatologic clinics, 2020

Research

Overview of common oral lesions.

Malaysian family physician : the official journal of the Academy of Family Physicians of Malaysia, 2022

Research

Oral surgery II: Part 4. Common oral lesions.

British dental journal, 2017

Research

Management of Oral Manifestations of Herpes Simplex Virus, Varicella Zoster Virus, and Human Papillomavirus.

Compendium of continuing education in dentistry (Jamesburg, N.J. : 1995), 2024

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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