What Vitamin Deficiency Causes Cracked Mouth Corners?

Cracked, sore corners of the mouth, a condition doctors call angular cheilitis, is most often linked to deficiencies in B vitamins, particularly riboflavin (B2), vitamin B12, and folate. Iron and zinc deficiencies frequently show up alongside these vitamin shortfalls and can produce the same painful splits on their own. The condition is common enough that most clinicians treat it as a red flag for poor nutritional status, but the relationship between what you eat and what happens at the corners of your lips is more layered than a single missing vitamin.

Riboflavin Is the Classic Culprit

Among all the nutrients tied to cracked mouth corners, riboflavin (vitamin B2) has the longest and most consistent track record. Riboflavin plays a central role in maintaining the mucous membranes that line your mouth, and when levels drop, the skin at the lip commissures (where the upper and lower lips meet) becomes fragile, dry, and prone to fissuring. DermNet, a widely used clinical dermatology resource, lists riboflavin deficiency as a specific nutritional risk factor for angular cheilitis.¹ Riboflavin deficiency rarely occurs in isolation, though. People who are low in B2 tend to be low in other B vitamins as well, because these nutrients share many of the same food sources: dairy, eggs, lean meats, and leafy greens. That clustering makes it hard to pin angular cheilitis on a single missing nutrient in many real-world cases.

Vitamin B12 and Folate Deficiency

Vitamin B12 and folate deficiencies are the other major B-vitamin players. Both are essential for healthy red blood cell production and for maintaining the rapidly dividing cells that line the mouth. When either runs low, the oral mucosa thins, becomes inflamed, and heals poorly. Angular cheilitis can appear as part of a broader pattern of oral changes, including a sore, swollen tongue (glossitis) and mouth ulcers. A classification review of cheilitis published in Acta Clinica Croatica noted that angular cheilitis can present as part of systemic conditions including anemia caused by vitamin B12 or iron deficiency.²

B12 deficiency is particularly common among older adults, whose stomachs produce less of the acid needed to extract the vitamin from food. Strict vegans are also at risk, since B12 occurs naturally almost exclusively in animal products. Folate deficiency is less common in countries where flour and cereal are fortified, but it still shows up in people with limited diets, heavy alcohol use, or conditions that impair absorption.

Iron Deficiency and Anemia

Iron deficiency is not a vitamin deficiency, strictly speaking, but it is one of the most frequently identified nutritional causes of cracked mouth corners and deserves a direct mention because the two are so tightly linked in clinical practice. Low iron leads to iron deficiency anemia, which starves tissues of oxygen and slows the body’s ability to repair the delicate skin at the lip corners. Angular cheilitis is recognized as one of the oral manifestations of iron deficiency anemia in both dermatology and internal medicine literature.³

Iron and B12 deficiencies overlap more than people realize. Both cause anemia, and a person can be deficient in both simultaneously, especially if the underlying cause is poor dietary intake or a malabsorption condition like celiac disease. DermNet lists celiac disease, iron deficiency, and general protein deficiency alongside the B-vitamin shortfalls as nutritional risk factors.¹ If you are told your cracked lip corners are from “anemia,” it is worth knowing which type of anemia, because the dietary fix is different for iron versus B12.

Zinc and Vitamin B6

Zinc deficiency gets less attention in popular health content, but it is a well-documented trigger for angular cheilitis. Zinc is critical for wound healing and immune defense in the skin. When levels drop significantly, the corners of the mouth crack and surrounding skin can develop a red, scaly rash. A case report in BMJ Case Reports described a woman who developed angular cheilitis, glossitis, and a spreading rash six years after Roux-en-Y gastric bypass surgery. Her serum zinc and vitamin B6 levels were critically low. The symptoms improved over two weeks once she began oral zinc and B6 replacement.⁴

Vitamin B6 (pyridoxine) deficiency on its own is relatively uncommon in well-nourished populations, but it crops up in people with absorption issues, chronic alcohol use, or certain medications that interfere with B6 metabolism. The case above is a useful illustration of how multiple nutrient deficiencies often pile up in the same person, especially after weight-loss surgery, and it can be hard to tease apart which missing nutrient deserves the blame for a given symptom.

When Cracked Corners Are Not About Nutrition at All

Here is where the picture gets more complicated: most cases of angular cheilitis in otherwise well-nourished people are not caused by a vitamin deficiency. The condition has several non-nutritional triggers, and sometimes a nutrient gap is a contributing factor rather than the sole cause.

The most common non-nutritional culprits include:

Candida infection: Yeast, particularly Candida albicans, thrives in the warm, moist environment at the lip corners. Once the skin cracks, yeast colonizes the fissure and prevents healing. Many angular cheilitis cases involve a fungal component regardless of what started the problem.
Saliva and lip habits: Chronic wetting of the lip corners from drooling, lip licking, or thumb sucking creates an environment ripe for breakdown. A cross-sectional study found a significant association between self-reported saliva pooling at the corners of the mouth and angular cheilitis.⁵
Ill-fitting dentures: Dentures that sit too low cause the mouth to over-close, creating deep folds at the corners where saliva pools. This is one of the most common mechanical triggers in older adults and can occur even when nutrition is perfectly adequate.
Medications: Isotretinoin, a potent acne drug, causes cheilitis (general lip dryness and cracking) in a large majority of users. One prospective study found cheilitis in 75% of patients on isotretinoin.⁶ That rate is strikingly high, and while isotretinoin-related lip cracking tends to affect the entire lip rather than just the corners, the corners can be involved.

The practical takeaway is that jumping straight to vitamin supplements without considering these other causes can mean you spend weeks taking B2 pills while the real problem is a yeast infection that needs an antifungal cream, or a denture that needs refitting.

Who Is Most Vulnerable to Nutritional Angular Cheilitis

If your diet is reasonably varied and you have no absorption issues, nutritional angular cheilitis is unlikely to be your problem. The people at genuine risk for nutrient-driven cracked mouth corners tend to fall into specific groups.

People who have had bariatric surgery are near the top of the list. Procedures like Roux-en-Y gastric bypass reroute the digestive tract in a way that dramatically reduces absorption of iron, zinc, B12, and other nutrients. Deficiencies can emerge years after the surgery, as the case report of combined zinc and B6 deficiency six years post-bypass illustrates.⁴ These patients need lifelong monitoring and supplementation, and angular cheilitis can be one of the first visible signs that supplementation has lapsed or is insufficient.

People with celiac disease, Crohn’s disease, or other inflammatory bowel conditions face similar absorption challenges. The inflammation in the gut wall disrupts the normal uptake of multiple nutrients at once, which is why angular cheilitis in these patients often reflects a bundle of deficiencies rather than a single one. DermNet lists celiac disease specifically among the risk factors.¹

Heavy alcohol use is another major risk factor. Alcohol interferes with the absorption and metabolism of B vitamins, depletes zinc, and replaces nutrient-dense food with empty calories. Chronic drinkers are prone to developing riboflavin, folate, and B6 deficiency simultaneously.

Older adults in institutional care, people on highly restrictive diets (whether for medical reasons or by choice), and individuals with eating disorders round out the high-risk groups. In all of these cases, the pattern is the same: reduced intake or absorption of the nutrients the oral mucosa depends on, leading to tissue fragility at the vulnerable lip corners.

Getting an Accurate Diagnosis

If you develop persistent cracking at the corners of your mouth, a clinician will typically do a few things. First, they will look at the lesion itself. Angular cheilitis from nutritional deficiency looks essentially the same as angular cheilitis from yeast infection or mechanical causes: red, cracked, sometimes crusted fissures at one or both lip commissures. The appearance alone does not reveal the cause, which is why further investigation matters.

A swab of the fissure can identify whether Candida or bacteria are colonizing the area. Blood work can check iron levels, a complete blood count to look for anemia, and levels of B12, folate, and sometimes zinc. Riboflavin testing is less commonly done in routine practice because isolated B2 deficiency is rare in developed countries, but it can be measured if other B-vitamin levels come back low.

The reason this matters practically is that many cases of angular cheilitis involve more than one cause at the same time. A person with mild iron deficiency and a habit of licking their lips, for instance, may need both iron supplementation and a barrier balm to keep saliva off the affected area. Someone with a yeast infection on top of B12 deficiency needs an antifungal along with the vitamin. Treating only one cause while ignoring the other leaves the problem half-solved.

What Treatment Involves

Treatment depends on what the evaluation uncovers. For confirmed nutritional deficiencies, supplementation is straightforward. B12 can be given orally in most cases, though people with absorption issues may need intramuscular injections. Iron supplements are widely available but can cause stomach upset, so timing and formulation matter. Zinc is typically replaced orally as well.

A narrative review of angular cheilitis treatment noted that B-vitamin supplementation has been proposed alongside a range of other approaches, including topical antifungals, restoration of occlusal vertical dimension (correcting how dentures make the jaw close), and even anti-drooling prosthetic devices, though most of the evidence for these approaches remains limited to case reports and small case series.⁷ That is worth keeping in mind: the treatment literature for angular cheilitis is not as robust as you might expect for such a common complaint. Much of clinical practice is guided by experience and pattern recognition rather than large randomized trials.

For the infectious component, topical antifungal creams (like miconazole or nystatin) or combination creams that include a mild steroid are the standard first-line treatments. These tend to work quickly when infection is the primary driver, often showing improvement within a week or two. If the underlying nutritional cause is not addressed, though, the cracks tend to come back once the cream is stopped.

Common Misconceptions About Cracked Mouth Corners

One widespread belief is that angular cheilitis always signals a vitamin deficiency. In reality, mechanical and infectious causes are at least as common in well-nourished populations. Cold, dry weather can trigger it. So can constant mask-wearing if moisture gets trapped at the lip corners. Drooling during sleep is an underappreciated cause, especially in people who sleep on their sides or breathe through their mouths.

Another misconception is that applying chapstick or lip balm to the corners will help. Standard lip balms are designed for the lip surface, not the commissures. Some contain fragrances or flavors that further irritate cracked skin. A plain, unfragranced barrier ointment like petroleum jelly tends to work better for protecting the area while it heals.

There is also a tendency online to self-diagnose angular cheilitis as a sign of B12 deficiency specifically, possibly because B12 gets more media attention than riboflavin or iron. While B12 deficiency can cause it, riboflavin and iron are equally plausible nutritional explanations, and the condition frequently has nothing to do with any nutrient at all. Self-supplementing with high-dose B12 when the real issue is a yeast infection just delays getting the right treatment.

The Relationship Between Oral Health and Systemic Nutrition

The mouth is one of the first places nutritional problems become visible, because the tissues lining the oral cavity turn over rapidly and depend heavily on a steady supply of B vitamins, iron, and zinc to regenerate. Angular cheilitis is just one member of a family of oral signs that clinicians use as clues to underlying nutritional status. Glossitis (a swollen, smooth tongue), recurrent mouth ulcers, and changes in the color or texture of the oral mucosa can all point in the same direction.

Niacin (vitamin B3) deficiency, for instance, causes characteristic tongue changes that were historically recognized as an early sign of pellagra. Research as far back as the 1940s documented that niacin supplementation could reverse these tongue abnormalities.⁸ Pellagra is rare today in developed countries, but mild B3 insufficiency can contribute to oral inflammation in populations with limited dietary variety.

For anyone experiencing angular cheilitis along with other oral symptoms like tongue soreness, unusually pale gums, or persistent mouth sores, the combination is a stronger signal that nutrition may be involved. Isolated cracked corners without other symptoms are more likely to have a local explanation like yeast, saliva exposure, or skin irritation. That distinction is useful to bring up with your doctor, because it helps guide whether blood work is warranted or whether a topical treatment alone is a reasonable first step.