Possible Causes of Lip Sores and When to Contact a Doctor

Medically Reviewed By Debra Rose Wilson, Ph.D., MSN, R.N., IBCLC, AHN-BC, CHT
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A lip sore may appear as a smooth, swollen bump or a dry, cracked lesion on or near the surface of the lips. Some lip sores heal on their own, but others require medical attention. Lip sores may occur after minor trauma, such as biting or burning your lip while eating. However, underlying health issues can also result in lip sores.

Cold sores are a type of lip sore caused by a herpes simplex virus type one (HSV-1) infection. In some rare cases, oral cancer may also cause lip sores.

Seek immediate medical care if your lip sore occurs in conjunction with a high fever and difficulty breathing or swallowing. Lip sores that do not show healing progress over a period of weeks or months could indicate an infection that needs medical treatment.

This article provides an overview of lip sores, including common causes, home remedies, and when to contact a doctor.

What is a lip sore?

Man checking face and lip in bathroom mirror
ALTO IMAGES/Stocksy United

A lip sore is a blister, bump, lesion, or ulcer that occurs on or around the lips. The lip sore may feel painful, tender, or irritated. The surface of the sore may appear broken and bleeding, crusted and scabbed, or red and swollen.

The many causes of lip sores range from mild to serious. Lip sores are rarely the result of a fatal condition, and they usually do not pose a significant health risk. They may occur due to a single incident or recur frequently.

Lip sores are often the result of minor trauma. For example, you may develop a lip sore from biting your lip or burning it with hot food.

Canker sores, or aphthous ulcers, are another common type of lip sore. However, canker sores only appear on the interior of the mouth. Eating acidic foods may trigger canker sores.

Lip sores may also occur as a symptom of an underlying disease or serious condition. HSV-1 is a common cause of contagious, recurring lip sores called cold sores, or fever blisters. The World Health Organization (WHO) estimates that 3.7 billion people under age 50 years have HSV-1.

It is easy to confuse an acne lesion for a cold sore. However, acne lesions do not occur directly on the lip. Rather, they develop on parts of the body where there are hair follicles, such as the area around the lip. Cold sores usually feel tingly and come with a burning sensation in the preliminary stages. They are usually more painful than pimples and can form on or around the lips.

A rare but serious potential cause of a lip sore is oral cancer. These malignant tumors appear on the interior of the mouth and may cause pain and difficulty talking or breathing.

Lip sores rarely indicate a medical emergency. However, seek immediate medical care by calling 911 if you experience lip sores along with other serious symptoms, such as a high fever, difficulty breathing, or difficulty swallowing. Seek prompt medical care if your lip sore is persistent or causes you concern.

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

Oral symptoms that may occur alongside lip sores

Lip sores may accompany other symptoms affecting the mouth, including:

  • bleeding
  • a burning sensation
  • cracked lips or mouth corners
  • the development of small bumps or blisters
  • a dry mouth
  • an itchy feeling
  • redness or other discoloration, warmth, or swelling
  • tenderness

Symptoms that might indicate a serious condition

In some cases, lip sores may occur with other symptoms that might indicate a serious condition that requires immediate evaluation in an emergency setting. Seek immediate medical care by calling 911 for lip sores that occur alongside other serious symptoms, including:

What causes a lip sore?

Lip sores have many possible causes. The type and severity of a lip sore will vary with the underlying cause.

Lip sores are often the result of minor trauma, such as biting your lip or eating very hot food. Another common cause of lip sores is HSV-1, which results in cold sores.

Less commonly, lip sores may be a symptom of an underlying disease or serious condition, such as cancer or an infection.

Common causes of lip sores

Some common causes of lip sores include:

  • biting the lip
  • braces, poorly fitting dentures, and other physical irritants
  • HSV-1
  • hot foods and beverages
  • viral infections

Oral cancer symptoms

In rare cases, a lip sore could be a symptom of oral cancer. The American Cancer Society (ACS) advises contacting a doctor for a lip sore that does not heal.

The ACS lists other symptoms of oral cancer that may occur with a lip sore, including:

  • a lump or thick area in the lips, cheek, or mouth
  • a red or white patch on the tongue, gums, tonsil(s), or lining of the mouth
  • numbness in the lip, tongue, or another area of the mouth
  • pain or swelling in your jaw
  • difficulty chewing or swallowing
  • mouth pain that does not go away

If you have a lip sore that is causing you concern, contact a dentist, doctor, or another healthcare professional for an evaluation. Getting a prompt diagnosis can lead to more effective treatments if the cause is serious.

How doctors diagnose the cause of lip sores

To diagnose the cause of your lip sore, your doctor or licensed healthcare practitioner will perform a physical exam. They may also 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?

Your dermatologist may swab your lip sore to test it for HSV-1.

Because lip sores are a common symptom of genital herpes, your doctor may choose to test you for this type of herpes as well. This is a simple blood test. Knowing whether or not you have genital herpes can help you begin effective treatment and prevent spreading the infection to others.

What are the treatments for lip sores?

For lip sores that result from a viral infection such as HSV-1, a dermatologist will recommend or prescribe an antiviral medication. These medications may include:

Topical antivirals

  • 5% acyclovir (Zovirax) cream or ointment, with or without hydrocortisone
  • 1% penciclovir (Denavir) cream
  • 50-milligram buccal adhesive tablet

Oral antivirals

  • acyclovir (Zovirax)
  • valacyclovir (Valtrex)
  • famciclovir (Famvir)

Your dermatologist will discuss how these medications work and inform you of possible side effects to help determine the right treatment course.

Home care for lip sores

The American Academy of Dermatology recommends the following home remedies for lip sores:

  • Apply an over-the-counter (OTC) antiviral medication: It is best to do this as soon as you detect a cold sore. This can help reduce the time the cold sore lasts.
  • Take OTC pain relievers: These include acetaminophen (Tylenol) and ibuprofen (Advil). Topical gels or ointments that contain benzocaine, dibucaine, lidocaine, or benzyl alcohol can also help ease the pain.
  • Hold an ice pack on the sore: Applying a cold, damp towel for 5–10 minutes a few times each day can also help reduce swelling.
  • Avoid hot, acidic, salty, and spicy foods and beverages: These can irritate the lip sore and cause a burning sensation.
  • Gently dab petroleum jelly onto the sore and the area around it: This can help prevent dryness and cracking.

If your lip sore is a symptom of a more serious condition, such as oral cancer, your doctor will discuss treatment options in the context of your individual diagnosis to determine the right treatment plan for you.

Summary

Lip sores are small bumps, cracks, or areas of irritation that can result from a variety of causes. Other names for lip sores include “fever blisters” and “cold sores.”

The most common cause of lip sores is HSV-1. Less commonly, lip sores can result from genital herpes. In even rarer cases, a lip sore may indicate a more serious condition, such as oral cancer.

Your doctor or dentist can evaluate your lip sore to make an accurate diagnosis and begin prompt treatment.

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Medical Reviewer: Debra Rose Wilson, Ph.D., MSN, R.N., IBCLC, AHN-BC, CHT
Last Review Date: 2022 Mar 28
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.