Different Types Of Blisters On The Lip

People often assume that any lesion (sore) around the mouth is a cold sore (also called a fever blister). But did you know that a sore on your lip could appear for several other reasons, ranging from simple injuries to severe health conditions?

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What causes sores on the lip?

You can have a sore on your lip that’s not a cold sore. It would manifest as a bump and would have a different shape and characteristics to a common cold sore. The sore’s surface might appear red and swollen, broken and bleeding, or crusted and scabbed.¹

Here are the common causes of sores on the lips:

Canker sores

These are usually white or yellow with a red border appearing inside the mouth or on the gums. You might experience tingling, burning, soreness, pain, fever, or swollen lymph nodes.²

Canker sores may appear due to stress, food allergies, vitamin B deficiency, or trauma.

Allergic contact dermatitis

Some skin products and cosmetics can react on the skin, causing irritation and inflammation.

Allergic contact dermatitis is an eczematous skin disease associated with stinging, soreness, burning, itching, and pain. It can look like pus-filled bumps that may ooze or crust and feel tender. You may also experience scaly, tough, hyperpigmented, or leathery skin.³

Angular cheilitis

Angular cheilitis is an inflammatory condition that causes symptoms that are similar in appearance to cold sores. You might develop red, swollen patches in the corners of your mouth and on the outside of your lips, along with cracked, dry skin.⁴


This is a sexually transmitted infection (STI) caused by a bacteria called Treponema pallidum. It can cause sores around the mouth, anus, and genitals.

The primary symptom, usually a hardened ulcer, typically appears 10–90 days after exposure.⁵

At the beginning of the infection, you may develop a firm, round, and painless sore on the genitals, anus, mouth, or fingertips. This is known as a chancre.

At a later stage, rough and circular red or brown spots may appear on the palms of your hands and the bottoms of your feet. The rash may also appear on your chest.

Another symptom of the infection is condyloma lata — large, raised sores that occur on your underarms, mouth, or groin area. During this phase, you might also have:⁶

  • Fever

  • Sore throat

  • Fatigue

  • Weight loss

  • Patchy hair loss

  • Muscle aches

  • Swollen lymph nodes

  • Headaches

Actinic cheilitis

Excessive long-term sun exposure can cause this type of lesion to form, most commonly on the lower lip.

Actinic cheilitis is a pre-cancerous sore.⁷ Left untreated, it may transform into malignant cells, causing a common type of lip skin cancer called squamous cell carcinoma (SCC).

This sore is often painless, but it may cause a painful, burning, or numb sensation in some cases.

Actinic cheilitis may initially look like chapped lips. In some cases, they are swollen. If it persists, you might see white scaly skin that may feel like sandpaper. It can eventually become ulcerated.

Oral and lip cancer

Oral cancer can manifest as patchy pigmentation or white spots with small ulcers on the inside of the lips. They may initially look similar to canker sores.

With oral cancer, you may experience numbness of the tongue, swelling of the jaw or lips, ear pain, and difficulty eating or swallowing.

Oral cancer risk is increased by alcohol and tobacco use, human papillomavirus (HPV), genetics, and aging.⁸

These sores don’t respond to common treatments.

Lip cancer can also be considered a type of oral cancer. It may occur anywhere on the outside of the upper or lower lip, but it’s more common on the lower lip. Lip cancer appears as a flat or raised whitish sore on the lip that won’t heal. It may cause pain, numbness, or tingling on the lip or around the mouth.

Other causes of lip sores

Many lip sores don’t result from conditions or viruses. However, it’s best to talk to your doctor to be certain about your diagnosis and the best course of treatment.

Allergic reactions to food

Some foods can trigger an allergic response in some people, causing redness, swelling, and painful sores.⁹


Bite trauma is a common cause of lip soreness. Bites can present as thickening skin inside the mouth, redness, scarring, a frayed surface, and paler skin.¹⁰


Eating foods that are too hot or spicy may cause burns. You may then develop lip sores, redness, irritation, or pain.

Irritation from braces

Many people report redness, ulcers, and pain as a result of their teeth-straightening braces.¹¹

Herpetic gingivostomatitis

This condition is caused by the herpes simplex virus (HSV) and occurs in young children.

It causes blistering sores on the gums and inside the lips. The infection can sometimes spread to other parts of your body, including your genitals and nose. 

Reactions to radiation

You might develop sores on your lips or inside your mouth if you are undergoing radiation therapy or chemotherapy.¹² This is called oral mucositis, meaning inflammation of the mucosa that lines your mouth.

You may develop mouth ulcers with soft white patches of pus. Your lips may become red and swollen and may also bleed.

Sucking blisters

These can occur in newborn infants, appearing on the knuckles, wrists, and other areas the baby sucks.¹³ In rare cases, sucking blisters appear on the lips and present as tense, fluid-filled blisters.¹⁴

Sunburn blisters

These can appear on the lips and cause significant pain. They don’t show up straight after sun exposure but may appear after several hours.

You can expect to see small, fluid-filled lesions that appear white.

Could the sore on your lip be a cold sore?

The sore on your lip could be a cold sore. However, this is only possible with HSV-1.¹⁵

Your doctor may perform a physical examination and take a swab to correctly diagnose your sore. They may ask you various questions about the sore, such as:

  • Have you had a similar lip sore before?

  • Do you have an existing chronic health condition?

  • Are you taking any medication?

  • How long have you had the sore?

  • What other symptoms are you experiencing?

What causes cold sores?

HSV-1 causes cold sores. They manifest as painful, fluid-filled sores and may recur many times in your life.

A World Health Organization (WHO) report indicates that around 3.7 billion people under the age of 50 have HSV-1.¹⁶ It’s highly contagious and can be transmitted from one person to another through skin contact or saliva.

What triggers cold sores?

Cold sore symptoms may not present straight after you pick up the viral infection.¹⁷ HSV can remain dormant within your body until your immune system is stressed.

Here are some common triggers that reactivate the virus:

  • Physical or emotional stress

  • Depression

  • Exposure to extreme weather conditions

  • Dental procedures

  • Other infections

Some other health conditions that can trigger cold sores include:

  • Hormonal changes such as menstruation or pregnancy

  • Other medical conditions that affect the immune system

  • The use of immunosuppressants after organ transplant

Cold sore symptoms

Tingling and itching around the lips are the most prevalent warning signs. You may feel a burning sensation on the lips around 12–24 hours before a small, hard, painful spot appears and erupts into a blister.

When warning signs persist, you’ll notice a raised bump filled with clear, white, or dark fluid. The bump is usually painful and tender.

You may develop a single sore or many clustered on your lip. They may rupture and ooze fluid, then crust and scab over when the healing process begins. This phase takes about a week, but the sore may not fully heal for a week or more.

Alongside the sore on your lip, you may experience one of the following symptoms:

  • Muscle aches

  • Fever

  • Swollen lymph nodes

Treating lip sores

While lip sores are unlikely to cause serious health conditions, you don’t have to let them continue causing irritation. 

Treating cold sores

There is no specific cure for cold sores, but your doctor can recommend treatments like antiviral or topical medications to control your symptoms and accelerate healing.

Here are the typical prescription medications for cold sores:¹⁸

  • Antiviral creams (e.g., docosanol or acyclovir cream)

  • Oral pills (e.g., acyclovir, valacyclovir, or famciclovir)

Follow the prescription regime recommended by your doctor carefully.

Treating canker sores

Over-the-counter gels can help numb the pain (e.g., benzocaine, fluocinonide, or hydrogen peroxide).¹⁹

You may also take non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen to ease the pain if local gels are ineffective.

Antiseptic mouthwash can help keep the inside of your mouth clean. This is important to reduce inflammation and improve healing.

To assist in the healing process, your doctor may recommend:²⁰

  • Avoiding allergen-causing foods and spices

  • Using sunscreen on the lip area

  • Trying to keep the area clear of irritants

Home remedies

The following home remedies can reduce the severity and pain of cold sores:²¹

  • Hold an ice pack on the sore for at least five minutes daily to minimize swelling.

  • Avoid hot, spicy, or acidic foods and drinks that can increase irritation and burning.

  • Apply petroleum jelly on the sore to maintain moisture and prevent cracking and dryness.

  • Avoid exposure to extreme temperatures or direct sun without wearing sunscreen.

When to see a doctor

If you have a lip sore that takes too long to heal, doesn’t respond to medication and home remedies, or keeps coming back, it may be time to seek medical treatment. Be sure to tell your doctor about all the symptoms you are experiencing to help them make the correct diagnosis.

How are lip sores diagnosed?

Many lip conditions discussed in this guide resolve on their own, but you should contact your doctor immediately if the sores are getting significantly worse despite treatment or spread to other areas of your body.

Your doctor will inspect the area and perform the appropriate investigation and tests to diagnose the sore and uncover whether there is an underlying condition that may be causing it. 

Blood tests are another diagnostic tool your doctor may use. They may also take a sample of fluid from the sore to test.

The lowdown

Sores on the lips can occur in anyone, regardless of their age. They often manifest as small, raised patches of skin that may be swollen or filled with fluid.

Developing a sore on your lip doesn’t always mean you have a cold sore. Something else might have caused it, such as trauma or allergies. In some cases, more serious conditions such as oral cancer or syphilis cause lip sores. A cold sore is caused by the contagious virus HSV-1.

Monitor your symptoms and speak to your doctor if the sore on your lip doesn’t heal on its own or with at-home treatments. Consider other symptoms you may have and discuss them with your doctor.


How long do lip sores last?

This depends on the type of sore you have and what’s causing it. For example, a cold sore may take over a week to heal.

How do you care for a sore on your lips?

Be sure to cover the sore to keep it protected from irritants. Use clean padding to protect the area. Don’t pop or drain the sore and keep the area clean.

You can try pain relievers if you experience a fever or if the sore is painful. Ice packs and lip balms may be helpful for cold sores.²²

Can stress cause sores on the lips?

Stress can trigger cold sores and other types of lip sores.

What does a lip infection look like?

Fungal infections of the lip often present with white patches, redness, or soreness on the corners of your mouth and outer or inner lips. These signs may indicate a lip infection.²³

  1. Fever Blisters & Canker Sores | National Institute of Dental and Craniofacial Research

  2. Skin Allergies — Causes, Symptoms & Treatment | American College of Allergy, Asthma & Immunology

  3. Contact Dermatitis (2023)

  4. Angular Cheilitis - An Updated Overview of the Etiology, Diagnosis, and Management (2021)

  5. Syphilis (2023)

  6. Syphilis – CDC Detailed Fact Sheet | Centers for Disease Control and Prevention

  7. Actinic Cheilitis (2022)

  8. Oral Cancer | National Institute of Dental and Craniofacial Research

  9. Recurrent aphthous stomatitis caused by food allergy (2010)

  10. Habitual biting of oral mucosa: A conservative treatment approach (2013)

  11. Oral mucosal ulceration during orthodontic treatment: The perception of patients and knowledge and attitude of the orthodontic practitioners (2020)

  12. Radiation Induced Oral Mucositis (2009)

  13. Vesicular, pustular, and bullous lesions in the newborn and infant | MediLib

  14. Blistering Distal Dactylitis (2022)

  15. Cold sore | NHS Inform

  16. Herpes simplex virus | The World Health Organization (2023)

  17. Fever Blisters & Canker Sores | National Institute of Dental and Craniofacial Research

  18. Cold sores: Diagnosis and treatment | American Academy of Dermatology Association

  19. Fever Blisters & Canker Sores | National Institute of Dental and Craniofacial Research

  20. (As above)

  21. Cold sores: Diagnosis and treatment | American Academy of Dermatology Association

  22. How to prevent and treat blisters | American Academy of Dermatology Association

  23. Candida infections of the mouth, throat, and esophagus | Fungal Diseases | Centers for Disease Control and Prevention

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