B12 Deficiency and Cracked Corners of the Mouth

Cracks at the corners of the mouth can be small, but they can feel surprisingly painful. They may sting when you talk, burn when you eat acidic foods, split open when you smile, or keep returning after they seem to heal. Many people assume it is just dry lips, but persistent cracking at the mouth corners can have a more specific name: angular cheilitis.

Vitamin B12 deficiency is one possible factor. Low B12 can affect the mouth, tongue, blood cells, and nervous system. In some people, it may appear with oral symptoms such as glossitis, mouth soreness, recurrent ulcers, burning sensations, taste changes, and cheilitis. However, cracked mouth corners are not specific to B12 deficiency. They can also be linked with saliva buildup, yeast or bacterial infection, dentures, lip licking, dry mouth, diabetes, immune issues, iron deficiency, folate deficiency, riboflavin deficiency, zinc deficiency, and irritation from dental products.

The safest answer is this: B12 deficiency can be one possible cause of cracked corners of the mouth, but angular cheilitis should not be blamed on B12 without looking for other common causes.

Quick Answer

Yes, low B12 may contribute to cracked corners of the mouth in some people, especially when the cracking appears with other oral symptoms, fatigue, tingling, numbness, anemia-like symptoms, or risk factors for poor B12 absorption. A review of oral manifestations of vitamin B12 deficiency lists cheilitis, glossitis, recurrent ulcers, dysgeusia, lingual paresthesia, and burning sensations among possible oral findings.

However, cracked mouth corners are often caused by angular cheilitis, which Cleveland Clinic describes as an inflammatory condition affecting one or both corners of the mouth and causing irritated, cracked sores. The cause is often broader than one vitamin.

Clinical Bottom Line

Low B12 is worth checking when cracked mouth corners are persistent, recurrent, slow to heal, or appear with a sore tongue, burning mouth, mouth ulcers, taste changes, fatigue, tingling, numbness, balance problems, or risk factors such as vegan diet, metformin use, proton pump inhibitor use, gastric bypass, Crohn’s disease, celiac disease, pernicious anemia, autoimmune gastritis, or older age.

But if the main problem is cracking at the mouth corners, the evaluation should also consider angular cheilitis, saliva pooling, Candida or bacterial infection, dentures or dental appliances, dry mouth, diabetes, immune status, iron deficiency, folate deficiency, riboflavin deficiency, zinc deficiency, and local irritation.

Key Takeaways

• Cracked corners of the mouth are often called angular cheilitis.
• Low B12 can be one possible factor, but it is not the only cause.
• B12-related cracked corners are more suspicious when other B12 symptoms are present.
• Iron, folate, riboflavin, and zinc issues can also be involved.
• Saliva buildup, lip licking, dentures, yeast, bacteria, diabetes, and dry mouth are common contributors.
• Persistent or recurring cracks should be evaluated by a doctor, dentist, or dermatologist.
• B12 supplements may help only if B12 deficiency is truly part of the cause.

What Are Cracked Corners of the Mouth?

Cracked corners of the mouth usually refer to irritation, splitting, redness, soreness, or crusting where the upper and lower lips meet. The medical term is often angular cheilitis, also called angular stomatitis or perlèche.

It may affect one side or both sides. It can look like a small split, red patch, flaky area, crusted sore, or moist irritated crack. Sometimes it feels worse than it looks.

Common symptoms include:

• Cracks at one or both mouth corners
• Redness
• Stinging
• Burning
• Soreness
• Flaking
• Crusting
• Bleeding when opening the mouth
• Pain when eating acidic or spicy foods
• Recurrent splitting after partial healing

This is different from ordinary chapped lips. Chapped lips usually affect the lip surface more broadly. Angular cheilitis is concentrated at the corners.

How B12 Deficiency May Affect the Mouth Corners

Vitamin B12 is required for healthy red blood cell formation, DNA synthesis, and normal nervous system function. The NIH Office of Dietary Supplements notes that B12 deficiency can cause symptoms including fatigue, neurological changes, megaloblastic anemia, glossitis of the tongue, palpitations, and low counts of red and white blood cells.

The mouth contains rapidly renewing tissue. When B12 is low, the oral lining may become more vulnerable to soreness, inflammation, delayed healing, and abnormal sensations. In some people, low B12 appears with cheilitis or irritation around the mouth.

B12-related cracked corners may be more likely when they occur alongside:

• Sore or swollen tongue
• Burning tongue
• Mouth ulcers
• Taste changes
• Fatigue
• Pale or yellowish skin
• Tingling in the hands or feet
• Numbness
• Balance problems
• Brain fog
• Shortness of breath
• Heart palpitations

Cracked corners alone do not prove B12 deficiency. The pattern matters.

Angular Cheilitis Is Not Always From Low B12

This is the most important point. Angular cheilitis is a visible mouth-corner problem, not a diagnosis of B12 deficiency.

StatPearls explains that angular cheilitis can require evaluation for infection, irritants, allergies, systemic disease, and nutritional deficiency, and notes that nutritional testing may include folate, vitamin B12, homocysteine, or methylmalonic acid.

A practical way to think about it:

Possible cause	Why it matters
Low B12	May contribute when other B12 symptoms or risk factors are present.
Iron or folate deficiency	Can overlap with mouth soreness, fatigue, and anemia-like symptoms.
Riboflavin deficiency	Merck Manual describes angular cheilitis and cheilosis as common signs.
Saliva pooling	Moisture at the corners can irritate skin and encourage yeast or bacteria.
Candida or bacteria	Infection can keep cracks inflamed or recurrent.
Dentures or dental appliances	Fit, friction, and saliva trapping can contribute.
Diabetes	Can increase dry mouth, infections, and delayed healing risk.
Dry mouth	Reduced saliva quality or mouth breathing can irritate tissue.
Lip licking	Repeated wet-dry cycles can worsen cracking.

B12 Deficiency vs Riboflavin, Iron, and Folate

B12 is not the only nutrient to consider. The mouth corners are a classic place where several deficiencies can look similar.

Merck Manual states that riboflavin deficiency commonly causes pallor and maceration of the mucosa at the mouth angles, called angular cheilitis, and cheilosis of the lips.

Iron and folate deficiencies can also overlap with mouth soreness, fatigue, weakness, anemia-like symptoms, glossitis, and recurrent oral problems. That is why a clinician may check more than B12 when cracks keep returning.

If someone takes B12 but the cracks do not improve, the cause may not be B12. It may be saliva, yeast, bacteria, denture fit, iron, folate, riboflavin, diabetes, dry mouth, or another local trigger.

When Low B12 Is More Suspicious

B12 becomes more suspicious when cracked corners are part of a broader pattern.

Low B12 may be more likely if you also have:

• Burning tongue
• Smooth or red tongue
• Mouth ulcers
• Taste changes
• Tingling in the hands or feet
• Numbness
• Balance changes
• Fatigue or weakness
• Pale or yellowish skin
• Shortness of breath
• Heart palpitations
• Vegan or very low animal-food diet
• Long-term metformin use
• Long-term proton pump inhibitor use
• Gastric bypass or stomach surgery
• Crohn’s disease
• Celiac disease
• Pernicious anemia
• Autoimmune gastritis
• Older age

The NIH notes that causes of B12 deficiency include difficulty absorbing B12 from food, lack of intrinsic factor, gastrointestinal surgery, prolonged use of medications such as metformin or proton pump inhibitors, and dietary deficiency.

What Tests to Ask About

A doctor, dentist, or dermatologist may choose testing based on the pattern, oral exam, medical history, and whether the cracks keep returning.

Possible evaluations include:

• Oral and dental exam
• Review of dentures, braces, retainers, or dental appliances
• Check for Candida or bacterial infection
• Serum vitamin B12
• Complete blood count
• Methylmalonic acid if B12 status is unclear
• Homocysteine in selected cases
• Folate
• Ferritin and iron studies
• Riboflavin status when deficiency is suspected
• Zinc in selected cases
• Glucose or A1c
• Review of medications and dry mouth symptoms

The NIH notes that serum or plasma B12 is commonly used to assess B12 status, and methylmalonic acid is the most sensitive B12-related marker when B12 status needs confirmation.

What Not to Do

Do not assume every mouth-corner crack is a vitamin problem. Also do not ignore it if it is recurrent, painful, or slow to heal.

Avoid these mistakes:

• Taking high-dose B12 indefinitely without understanding the cause
• Ignoring saliva buildup at the corners of the mouth
• Using irritating lip products or harsh toothpaste
• Licking the corners repeatedly
• Ignoring dentures or dental appliances that trap saliva
• Ignoring possible yeast or bacterial infection
• Forgetting iron, folate, riboflavin, or zinc
• Assuming normal B12 levels explain everything
• Delaying care if the area bleeds, spreads, or does not heal

The goal is not to guess. The goal is to identify why the skin keeps cracking.

Can B12 Supplements Fix Cracked Corners?

B12 supplements may help if low B12 is truly contributing to the problem. They may not help if angular cheilitis is driven by Candida, bacteria, dentures, saliva pooling, lip licking, diabetes, dry mouth, iron deficiency, riboflavin deficiency, folate deficiency, zinc deficiency, or local irritation.

If B12 deficiency is confirmed, treatment may include oral B12, sublingual B12, or injections depending on severity, absorption issues, medical history, and clinician judgment.

Do not judge the cause only by whether a crack improves for a few days. Angular cheilitis can temporarily improve with barrier ointments and then return if the underlying trigger remains.

When to See a Doctor, Dentist, or Dermatologist

Seek evaluation if cracked mouth corners last more than two weeks, keep returning, become very painful, bleed, crust, spread, or appear with other symptoms.

Get checked sooner if you have:

• White patches in the mouth
• Mouth ulcers that do not heal
• Swelling
• Fever
• Trouble eating or swallowing
• Diabetes
• Immune suppression
• Unexplained weight loss
• Severe fatigue
• New tingling or numbness
• Balance problems
• Recent medication changes
• Poorly fitting dentures or dental appliances

Angular cheilitis is usually treatable, but persistent cases often need the cause identified.

Research Snapshot

Cracked mouth corners can appear with angular cheilitis, a condition that may involve local irritation, saliva pooling, Candida, bacteria, dental factors, systemic disease, or nutritional deficiencies. Vitamin B12 deficiency has documented oral manifestations, including cheilitis, glossitis, recurrent ulcers, dysgeusia, paresthesia, and burning sensations. However, B12 is not the only nutrient involved; riboflavin, iron, folate, and zinc should also be considered when the pattern fits.

Medical Disclaimer

This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Cracked corners of the mouth, angular cheilitis, mouth sores, burning mouth, tongue soreness, fatigue, tingling, numbness, and other symptoms can have many possible causes and should be evaluated by a qualified healthcare professional when persistent, recurrent, severe, or unexplained.

Do not start, stop, or change vitamin B12 supplements, injections, medications, antifungal treatments, antibiotics, dental treatments, or medical treatment plans without professional guidance, especially if you have anemia, neuropathy symptoms, diabetes, gastrointestinal disease, autoimmune disease, pregnancy, immune suppression, unexplained mouth lesions, or worsening symptoms.

Seek prompt medical or dental care if cracked mouth corners last more than two weeks, bleed, spread, crust severely, come with white patches, swelling, fever, trouble swallowing, unexplained weight loss, new weakness, balance problems, or rapidly worsening numbness or tingling.

Final Verdict

B12 deficiency can be one possible cause of cracked corners of the mouth, especially when the cracks appear with glossitis, mouth ulcers, taste changes, fatigue, tingling, numbness, or clear risk factors for low B12.

But cracked mouth corners are not specific to B12. They are often related to angular cheilitis, saliva pooling, yeast, bacteria, dentures, lip licking, dry mouth, diabetes, local irritation, riboflavin deficiency, iron deficiency, folate deficiency, or zinc deficiency.

The safest conclusion is simple:

Low B12 may be part of the picture, but persistent cracked mouth corners should be evaluated as angular cheilitis, not treated as a B12 problem alone.

Frequently Asked Questions

Can B12 deficiency cause cracked corners of the mouth?

Yes. B12 deficiency may contribute to cracked corners of the mouth in some people, especially when it appears with other oral symptoms, fatigue, tingling, numbness, or risk factors for poor B12 absorption.

What are cracked corners of the mouth called?

Cracked corners of the mouth are often called angular cheilitis, angular stomatitis, or perlèche. It affects one or both corners of the mouth and can cause redness, soreness, cracking, crusting, or bleeding.

Are cracked mouth corners always from low B12?

No. Cracked corners can come from saliva buildup, yeast, bacteria, dentures, lip licking, dry mouth, diabetes, iron deficiency, folate deficiency, riboflavin deficiency, zinc deficiency, allergies, or irritation.

What vitamin deficiencies cause cracked corners of the mouth?

Vitamin B12, riboflavin, folate, iron, and zinc deficiencies may be considered when mouth-corner cracks are recurrent or unexplained. Testing helps identify the most likely cause.

Can B12 supplements heal angular cheilitis?

B12 supplements may help if low B12 is part of the cause. They may not help if angular cheilitis is caused by Candida, bacteria, dentures, saliva pooling, diabetes, dry mouth, or another deficiency.

How do I know if cracked mouth corners are from B12?

B12 is more suspicious if cracks occur with burning tongue, mouth ulcers, taste changes, fatigue, tingling, numbness, balance problems, vegan diet, metformin use, proton pump inhibitor use, gastric surgery, or malabsorption conditions.

Should I see a dentist or doctor for cracked mouth corners?

A dentist can check dental appliances, saliva issues, oral irritation, and infection. A doctor or dermatologist can evaluate skin, nutritional deficiencies, diabetes, immune issues, and recurrent angular cheilitis.

When should I worry about cracked corners of the mouth?

Seek care if cracks last more than two weeks, keep returning, bleed, crust, spread, become very painful, or appear with white patches, fever, trouble swallowing, weight loss, fatigue, numbness, or weakness.