What causes a lip sore?

Lip sores have many causes. The type and severity of lip sore will vary with the underlying cause. Lip sores are often the result of minor trauma, such as biting your lip or eating extremely hot food. Other common causes of lip sores include herpes simplex virus infection resulting in a cold sore, as well as canker sores. Less commonly, lip sores may be a symptom of an underlying disease or serious condition, such as cancer or infection.

Common causes of lip sores

Common causes of lip sores include:

  • Biting your lip
  • Braces, poorly fitting dentures, or other physical irritants
  • Canker sores
  • Cold sores (herpes simplex virus infection)
  • Hot food and beverages
  • Stress
  • Viral infections
  • Vitamin B12 or folate deficiency

Less common causes of lip sores

Less commonly, lip sores can also be caused by:

  • Autoimmune disorders
  • Dermatitis (skin inflammation)
  • Hemophilia (rare hereditary disorder in which blood does not clot normally) or other bleeding disorders
  • Weakened immune system

Serious or life-threatening causes of lip sores

In some cases, lip sores may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

  • Cancer
  • Serious infection or abscess

Questions for diagnosing the cause of lip sores

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your lip sores including:

  • How long have you had the lip sores?
  • Have you experienced any minor trauma, such as biting or burning your lips?
  • Have you had similar lip sores before?
  • Are you experiencing any other symptoms along with your lip sores?
  • Do you have any chronic medical conditions?
  • What medications are you taking?

What are the potential complications of a lip sore?

In most cases, lips sores are not serious. Occasionally, lips sores may be due to serious disease, and failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Organ failure or dysfunction
  • Severe discomfort or pain
  • Skin ulcerations and infections
  • Spread of cancer
  • Spread of infection


  1. Mouth sores. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003059.htm.
  2. Mouth problems. FamilyDoctor.org. http://familydoctor.org/familydoctor/en/health-tools/search-by-symptom/mouth-problems.html.

What is a lip sore?

A lip sore is a blister, bump, lesion or ulcer occurring on the lips. The surface of the sore may be broken and bleeding or may be crusted or scabbed. The lip sore may be painful, tender or irritating and may look red and swollen.

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What other symptoms might occur with a lip sore?

Lip sores may accompany other symptoms, which will vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the lips may also involve other body systems.

Mouth symptoms that may occur along with lip sores

Lip sores may accompany other symptoms affecting the mouth including:

Medical Reviewer: Cynthia Haines, MD Last Annual Review Date: Aug 5, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Mouth, Teeth and Oral Health