Have you ever noticed painful cracks at the corners of your mouth that seem to disappear and return? Perhaps the skin splits when you smile, burns when you eat spicy food or becomes red and sore whenever you open your mouth widely.
For some people, the cracks appear on one side of the mouth. For others, both corners become inflamed, dry or crusty. Applying lip balm may provide temporary relief, but the irritation sometimes returns.
One common explanation is angular cheilitis, an inflammatory condition affecting the corners of the mouth.
Angular cheilitis can develop when saliva repeatedly collects in the corners of the lips, weakening the skin and allowing irritation or infection to develop. Other contributing factors include dry skin, poorly fitting dentures, nutritional deficiencies and certain medical conditions.
Although many cases are mild and treatable, persistent or recurring cracks may indicate an underlying problem that needs attention.
This article explains ten possible causes of cracked mouth corners, how to recognise angular cheilitis, available treatments, practical prevention tips and when to seek medical advice.
What Is Angular Cheilitis?
Angular cheilitis is inflammation affecting one or both corners of the mouth, medically called the oral commissures.
The condition can cause:
Redness or darker discolouration around the mouth corners.
Painful cracks or splits.
Dry, flaky or crusty skin.
Burning or stinging.
Mild swelling.
Discomfort when opening the mouth.
Occasional bleeding.
Repeated irritation after eating or drinking.
On darker skin, inflammation may appear brown, purple or darker than the surrounding skin rather than bright red.
Angular cheilitis is not the same as a cold sore, although the two conditions can sometimes be confused.
The underlying cause may involve irritation, infection or a combination of factors.
10 Possible Causes of Cracks at the Corners of the Mouth
1. Saliva Accumulation and Repeated Moisture
One of the most common contributors to angular cheilitis is repeated exposure to saliva.
Saliva may collect at the corners of the mouth, particularly during sleep or when the mouth remains slightly open.
Repeated wetting and drying can weaken the skin barrier.
Once the skin becomes irritated, small cracks may develop.
These damaged areas can become more vulnerable to fungal or bacterial infection.
2. Fungal Infection (Candida)
Candida yeast normally exists in small amounts in the mouth and on the skin.
Under certain conditions, it may contribute to inflammation at the mouth corners.
Angular cheilitis associated with Candida may occur alongside oral thrush, although the two do not always appear together.
Treatment may involve an antifungal cream prescribed or recommended by a healthcare professional.
Not every cracked mouth corner is caused by fungus, so antifungal treatment is not always necessary.
3. Bacterial Infection
Bacteria, including Staphylococcus aureus, can sometimes contribute to angular cheilitis.
The affected area may become inflamed, crusty or painful.
Some people have both fungal and bacterial involvement.
Treatment depends on the findings and may require a targeted topical medicine.
4. Dry Skin and Lip Licking
Dry or irritated skin around the mouth can crack more easily.
Frequently licking the lips or mouth corners may initially feel soothing, but saliva evaporation can worsen dryness.
Cold weather, wind and irritating skincare products may also contribute.
Avoiding repeated licking and protecting the skin barrier may help.
5. Poorly Fitting Dentures
Dentures that do not fit properly may alter how the lips and mouth corners meet.
This can create folds where saliva accumulates.
The resulting moisture may contribute to skin irritation and angular cheilitis.
People with dentures may also be more susceptible to certain oral fungal infections.
A dentist can assess whether denture adjustment is needed.
6. Iron Deficiency
Iron deficiency can sometimes contribute to changes affecting the lips, tongue and mouth.
Angular cheilitis may occur in some people with iron deficiency, particularly when other symptoms are present.
Possible accompanying symptoms include fatigue, weakness, shortness of breath and pale skin.
However, cracked mouth corners alone do not establish iron deficiency.
Blood tests may be appropriate when a deficiency is suspected.
7. Vitamin B Deficiencies
Certain B-vitamin deficiencies, including riboflavin (vitamin B2), may be associated with inflammation and cracking around the mouth.
Deficiencies involving other nutrients, such as vitamin B12 or folate, may also contribute to oral symptoms.
These deficiencies are not the cause of every case.
Taking multiple supplements without confirming a deficiency may be unnecessary and could delay proper diagnosis.
Related reading: Vitamin B12 Deficiency: 12 Signs and Symptoms, Causes, Testing and Treatment
8. Diabetes
Diabetes can increase susceptibility to certain infections, including Candida infections, particularly when blood glucose is poorly controlled.
Some people with diabetes also experience dry mouth or delayed healing.
These factors may contribute to recurring angular cheilitis.
However, cracks at the corners of the mouth are not a reliable way to diagnose diabetes.
9. Contact Dermatitis and Allergic Reactions
Some people develop irritation or allergic reactions to substances that contact the lips and surrounding skin.
Potential triggers include:
Lip cosmetics.
Toothpaste ingredients.
Fragranced skincare products.
Certain mouthwashes.
Dental materials.
Flavoured lip products.
Contact dermatitis may cause dryness, itching, burning or cracking.
Identifying and avoiding a confirmed trigger can help.
10. Other Skin and Medical Conditions
Conditions such as eczema can make the skin around the mouth more vulnerable to irritation.
Certain medical conditions affecting immunity, nutrition or saliva production may also increase the likelihood of recurring symptoms.
Occasionally, a persistent sore at the mouth corner may have a different explanation altogether.
A lesion that does not heal, changes in appearance or becomes unusually firm should be examined to exclude other conditions.
Why Do the Corners of My Mouth Keep Splitting?
Repeated splitting often occurs because the underlying cause has not been fully addressed.
For example, applying lip balm may temporarily protect the skin, but recurring saliva accumulation, denture problems or untreated infection may continue to cause irritation.
The cracks may reopen when you:
Smile widely.
Yawn.
Eat large bites of food.
Brush your teeth.
Stretch your lips.
Eat acidic or spicy foods.
Repeated symptoms deserve assessment, particularly if they persist despite gentle skincare.
Why Do I Get Cracks on Both Sides of My Mouth?
Angular cheilitis commonly affects both mouth corners, although one-sided symptoms can also occur.
When both sides are affected, possible contributors include repeated moisture exposure, denture-related changes, fungal infection or nutritional problems.
However, the location alone cannot establish the cause.
Are Cracks at the Corners of the Mouth a Sign of Vitamin Deficiency?
They can be, but vitamin deficiency is only one possible explanation.
Riboflavin, iron and other nutritional deficiencies may contribute to oral inflammation.
A deficiency becomes more likely when there are additional symptoms, relevant dietary restrictions, digestive conditions or other risk factors.
A clinician may recommend blood tests when appropriate.
Do not assume that every case of angular cheilitis requires vitamin supplements.
Angular Cheilitis vs Cold Sores: What Is the Difference?
Angular cheilitis and cold sores can affect nearby areas but are different conditions.
Feature | Angular cheilitis | Cold sore |
|---|---|---|
Typical location | Corners of the mouth | On or around the lips |
Appearance | Cracks, inflammation, crusting | Often grouped fluid-filled blisters |
Common causes | Moisture, irritation, Candida, bacteria | Herpes simplex virus |
Contagious? | Usually not itself contagious | Yes, especially during an active outbreak |
Symptoms | Splitting, burning, soreness | Tingling, burning, blisters and crusting |
Treatment | Depends on cause | Sometimes antiviral treatment |
Angular cheilitis may involve microorganisms, but the condition itself is not usually considered contagious in the same way as a herpes cold sore.
If the diagnosis is uncertain, seek professional advice.
Can Toothpaste Cause Cracks at the Corners of the Mouth?
Certain toothpaste ingredients may irritate sensitive skin.
For example, flavourings or other ingredients can trigger contact reactions in susceptible individuals.
However, toothpaste is not the most common explanation for angular cheilitis.
If symptoms began after changing toothpaste, a dentist or healthcare professional can help assess whether a product is contributing.
How to Treat Cracks at the Corners of Your Mouth
Treatment depends on the underlying cause.
1. Protect the affected skin
A thin layer of plain petroleum jelly or another suitable fragrance-free barrier ointment may help protect irritated skin from moisture.
Avoid applying products that cause burning or worsening irritation.
2. Avoid licking your lips
Repeated lip licking can worsen dryness and irritation.
Try to leave the affected area undisturbed.
3. Keep the mouth corners gently clean
Use water and gentle cleansing rather than harsh scrubbing.
Pat the skin dry carefully.
4. Treat confirmed fungal infection
If Candida is contributing, an appropriate antifungal treatment may be recommended.
Avoid repeatedly using antifungal creams without confirming the cause.
5. Treat bacterial infection when present
Some cases may require prescribed antibacterial treatment.
A healthcare professional can determine whether this is necessary.
6. Check denture fit
If you wear dentures, arrange a dental review if they are loose, uncomfortable or causing saliva to collect around the mouth.
7. Correct confirmed nutritional deficiencies
If blood tests identify iron or vitamin deficiencies, treatment should address both the deficiency and its underlying cause.
8. Avoid irritating products
Consider whether fragranced lip products, harsh skincare ingredients or certain oral hygiene products aggravate symptoms.
9. Manage underlying medical conditions
Appropriate management of diabetes, eczema or other relevant conditions may help reduce recurrence.
10. Seek professional advice if symptoms persist
If the cracks are not improving, keep returning or become increasingly painful, arrange an assessment.
How Long Does Angular Cheilitis Take to Heal?
Healing time varies depending on the cause and severity.
Mild irritation may improve within several days after the skin is protected and the trigger is addressed.
Infections or persistent underlying factors may require specific treatment and take longer to resolve.
Repeatedly reopening the cracks can delay healing.
If symptoms do not improve within approximately one to two weeks, or if they worsen, seek medical or dental advice.
Can You Use Vaseline for Angular Cheilitis?
Plain petroleum jelly can act as a barrier and help protect irritated skin from saliva.
It may be useful when moisture and dryness contribute to the problem.
However, petroleum jelly does not directly treat a fungal or bacterial infection.
If symptoms persist, an appropriate diagnosis is needed.
What Should You Avoid When You Have Cracked Mouth Corners?
While the area is irritated, it may help to avoid:
Repeatedly licking or picking the cracks.
Harsh exfoliating products.
Strongly fragranced lip products.
Very spicy or acidic foods if they cause pain.
Applying undiluted essential oils.
Using steroid creams without professional advice.
Steroid creams used inappropriately can worsen certain infections.
When Should You See a Doctor or Dentist?
Arrange an appointment if:
The cracks persist for more than one to two weeks.
Symptoms repeatedly return.
The affected area becomes increasingly painful.
There is significant crusting, discharge or swelling.
You have recurrent oral thrush.
You experience unexplained fatigue or other possible deficiency symptoms.
You have diabetes and the area is not healing.
A sore or lump persists despite treatment.
Seek urgent medical advice if redness or swelling spreads rapidly, you develop fever or you appear generally unwell.
A persistent unexplained lesion that does not heal within three weeks requires prompt assessment to exclude other oral conditions.
How Is Angular Cheilitis Diagnosed?
A healthcare professional or dentist will usually examine the corners of the mouth and ask about symptoms.
They may review:
Oral hygiene habits.
Denture use.
Lip licking.
Skincare and toothpaste products.
Medicines.
Medical conditions.
Nutritional risk factors.
Swab Tests
A swab may sometimes be taken if infection is suspected, particularly when symptoms are recurrent or difficult to treat.
Blood Tests
Tests may be recommended when iron deficiency, vitamin deficiency or diabetes is suspected.
Dental Assessment
A dentist can examine denture fit, oral hygiene and other possible contributing factors.
Further Investigation
A persistent or unusual lesion may require specialist examination or biopsy.
Not everyone with angular cheilitis needs laboratory tests.
How to Prevent Cracks at the Corners of Your Mouth
Prevention depends on the underlying cause, but useful measures may include maintaining gentle lip care, avoiding repeated licking and protecting the skin from prolonged moisture.
If you wear dentures, ensure they fit properly and follow recommended cleaning instructions.
Maintain a balanced diet and seek advice if you have symptoms suggesting a nutritional deficiency.
People with diabetes should follow their individual management plans.
Recurring symptoms should be investigated rather than repeatedly treated without identifying the cause.
Frequently Asked Questions
What causes cracks at the corners of the mouth?
Common contributors include saliva irritation, angular cheilitis, fungal or bacterial infection, dry skin and denture-related problems.
Is angular cheilitis contagious?
Angular cheilitis itself is generally not considered contagious, although microorganisms may contribute to some cases.
Can vitamin B12 deficiency cause cracked mouth corners?
It may contribute to oral changes in some people, but it is not the most common cause.
Can iron deficiency cause angular cheilitis?
Yes. Iron deficiency can be associated with angular cheilitis, particularly when other deficiency symptoms are present.
Can I use petroleum jelly on cracked mouth corners?
Plain petroleum jelly may help protect the skin, but it will not treat every underlying cause.
Why does angular cheilitis keep coming back?
Recurring symptoms may indicate ongoing saliva exposure, denture problems, infection, irritation or an underlying medical condition.
Is angular cheilitis the same as a cold sore?
No. Angular cheilitis is inflammation at the mouth corners, while cold sores are caused by herpes simplex virus.
Can cracked mouth corners be a sign of diabetes?
Diabetes may increase susceptibility to certain infections, but cracked mouth corners alone cannot diagnose diabetes.
The Bottom Line
Cracks at the corners of the mouth are often caused by angular cheilitis, a condition involving irritation and inflammation of the skin where the lips meet.
Saliva accumulation, fungal or bacterial infection, dry skin, denture problems and nutritional deficiencies may all contribute.
Many cases improve with appropriate skin protection and treatment of the underlying cause.
If cracks keep returning, fail to heal or become increasingly painful, seek medical or dental advice.
Identifying the reason for the irritation is the most effective way to reduce recurrence.
Related Reading
Why Do I Have White Patches on My Tongue? 10 Possible Causes and When to Worry
Why Do My Gums Bleed When I Brush My Teeth? 10 Possible Causes and When to Worry
Why Do I Keep Getting a Metallic Taste in My Mouth? 10 Possible Causes and When to Worry
Sources and Further Reading
DermNet — Angular Cheilitis — causes, symptoms and treatment.
NHS — Oral Thrush in Adults — oral Candida infections.
NHS — Iron Deficiency Anaemia — symptoms, causes and diagnosis.
NHS — Vitamin B12 or Folate Deficiency Anaemia — deficiency-related symptoms.
NHS — Cold Sores — recognising herpes-related lip lesions.
NHS — Mouth Cancer — persistent oral changes and warning signs.
Medical Disclaimer
This article is intended for general educational and informational purposes only and does not replace professional medical or dental advice, diagnosis or treatment.
Cracks at the corners of the mouth can have several causes, and symptoms alone cannot establish a diagnosis. Consult a qualified healthcare professional or dentist if symptoms persist, recur frequently, worsen or are accompanied by signs of infection or other concerning symptoms.
Do not use prescription medicines, steroid creams or antifungal treatments without appropriate guidance. Seek urgent medical assistance for rapidly spreading infection, significant swelling or serious illness.
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