Cracking at the corners of your mouth is almost always a condition called angular cheilitis, an inflammation of one or both lip commissures where moisture gets trapped and the skin breaks down. It looks and feels worse than it usually is, but it can become stubborn if the underlying cause goes unaddressed. The culprit is rarely just one thing: angular cheilitis typically involves a combination of excess moisture, microbial overgrowth, and one or more predisposing factors like nutritional gaps, dental issues, or skin habits.
How Moisture Starts the Problem
The corners of your mouth sit in a natural crease where the upper and lower lips meet, and that crease is a trap. Saliva pools there, especially during sleep or when the lips are held slightly apart. Once saliva sits in that fold for long enough, it softens and breaks down the outer layer of skin in a process called maceration. Saliva contains digestive enzymes, including amylase and lipase, that can irritate and inflame the softened tissue at the lip corners.1International Journal of Dentistry and Oral Science (IJDOS). Angular Cheilitis – An Updated Overview of the Etiology, Diagnosis, and Management What starts as mild redness progresses to cracking, crusting, and sometimes shallow ulcers if the wet-dry cycle continues.
This is why angular cheilitis tends to appear on both sides at once. The anatomy is symmetrical, so both corners of the mouth experience the same saliva exposure. One-sided cracking does happen, but if you’re dealing with bilateral fissures, it points strongly toward this moisture-driven mechanism rather than, say, a cold sore, which typically appears on just one side and involves blistering before it cracks.
The Microbes That Move In
Damaged, macerated skin is an open invitation for opportunistic organisms. Two microbes account for the vast majority of infected angular cheilitis cases: the yeast Candida albicans and the bacterium Staphylococcus aureus. A study of angular cheilitis lesions found pathogenic organisms in about 59% of cases, with Candida species identified in 24 patients and S. aureus in 11.2PubMed. Angular cheilitis in a group of Sri Lankan adults: a clinical and microbiologic study Sometimes both organisms are present at the same time, which can complicate treatment if you’re only targeting one of them.3PubMed. Phenotypic characterization of mononuclear cells and class II antigen expression in angular cheilitis infected by Candida albicans or Staphylococcus aureus
A key detail: these organisms don’t cause angular cheilitis the way a cold virus causes a cold. They’re opportunistic colonizers. Candida already lives in your mouth in small numbers, and S. aureus is commonly found on skin. They only become a problem when the corner of the mouth is already compromised by moisture, friction, or immune suppression. This is why simply applying an antifungal cream can clear the infection without curing the condition. If you don’t fix the underlying moisture issue or whatever else predisposed the skin to break down, it comes right back.
Nutritional Deficiencies That Make You Vulnerable
If your angular cheilitis keeps returning or resists treatment, a vitamin or mineral deficiency may be playing a role. Iron is one of the better-studied culprits. In a clinical study of patients with angular cheilitis, roughly 35% were found to have iron deficiency anemia.4Mustansiria Dental Journal. Angular Cheilitis and Iron Deficiency Anemia Iron is critical for maintaining healthy mucosal tissue, and when levels drop, the skin at the corners of the mouth becomes thinner and more prone to breakdown.
Iron isn’t the only nutrient involved. B vitamins, particularly B2 (riboflavin), B12, and folate, along with zinc, have all been associated with recurrent angular cheilitis.5Saudi Journal of Medicine and Public Health. Angular Cheilitis: A Multidisciplinary Approach to Clinical Diagnosis, Nutritional Assessment, Laboratory Evaluation, and Pharmacological Management B2 deficiency in particular can cause cracks and sores around the mouth as one of its earliest visible signs. If you’re on a restrictive diet, have absorption issues, or have been dealing with recurrent cracking that topical treatments don’t resolve, asking your doctor to check these levels is a reasonable step.
One thing worth knowing: a mild nutritional shortfall may not cause angular cheilitis on its own but can lower the threshold for it. You might go years with slightly low iron and never have a problem, then develop persistent cracking during a winter when dry air, a new toothpaste, or a course of antibiotics tips the balance. Correcting the deficiency won’t always cure the current episode, but it can help break the cycle of recurrence.
Dentures, Bite Changes, and Facial Anatomy
The vertical dimension of your face, meaning the distance between your nose and chin when your mouth is closed, has a direct bearing on angular cheilitis risk. Anything that reduces that distance creates deeper folds at the corners of the mouth, which means more saliva trapping, more maceration, and more opportunity for microbes to set up shop.
Denture wearers are especially affected. A study of older adults found that angular cheilitis was associated with complete tooth loss, reduced vertical dimension from worn-down dentures, poor denture stability, and the presence of oral Candida.6PubMed. Risk factors for denture-related oral mucosal lesions in a geriatric population The acrylic teeth in dentures wear down over time, and after about two years of use, the height loss becomes clinically relevant enough to warrant evaluation for replacement.7PubMed Central. Analysis of risk factors for maxillary denture-related oral mucosal lesions: A cross-sectional study
You don’t need dentures to run into this problem, though. Significant weight loss can reduce facial volume and deepen the creases at the mouth corners. Age-related bone resorption in the jaw does the same thing. Even a missing back tooth that hasn’t been replaced can subtly shift your bite and create asymmetry in the lip commissures. If cracking happens more on one side than the other, dental issues are worth investigating.
Lip Licking and Habitual Behaviors
When your lips feel dry or cracked, the instinct is to lick them. This provides a few seconds of moisture, followed by even more dryness as the saliva evaporates and strips the skin’s natural oils. If lip licking becomes a habitual loop, it can lead to a constellation of problems including irritant dermatitis around the lips, generalized cheilitis, and angular cheilitis at the corners.8PubMed Central. Art of prevention: Practical interventions in lip-licking dermatitis
Children and teenagers are particularly prone to this cycle, and you can often spot it by the ring of reddened, slightly scaly skin around the mouth that follows the area the tongue can reach. But adults do it too, sometimes without realizing it, especially during periods of stress or when mouth-breathing during sleep. Drooling during sleep produces the same effect at the corners of the mouth. People who use CPAP machines or who sleep with their mouths open frequently deal with angular cheilitis for this reason.
Breaking the habit is part of the fix. Applying a thick barrier product like petroleum jelly or a zinc oxide ointment before bed keeps saliva from pooling on the skin. During the day, reaching for a lip balm instead of licking serves the same purpose. The goal is to interrupt the wet-dry-wet cycle that keeps the skin from healing.
Systemic Diseases and Medications
Certain chronic illnesses can make angular cheilitis more likely or harder to treat. Inflammatory bowel disease, including both Crohn’s disease and ulcerative colitis, lists angular cheilitis among its non-specific oral manifestations.9PubMed Central. Oral pathology in inflammatory bowel disease In these cases, the cracking may partly reflect the nutritional malabsorption that comes with gut inflammation, and partly reflect the immune dysregulation itself.
Diabetes is another common risk factor. Elevated blood sugar promotes Candida overgrowth throughout the body, including in the mouth, and impairs wound healing. People with uncontrolled diabetes who develop angular cheilitis often find it difficult to clear without getting their blood sugar under better control first. HIV and other forms of immune suppression similarly raise the risk by weakening the body’s ability to keep commensal organisms like Candida in check.
Medications matter too. Isotretinoin (used for severe acne) dries out the lips dramatically and is a well-known trigger. Oral retinoids in general have this effect. Long courses of antibiotics can shift the microbial balance in the mouth and favor Candida overgrowth. Inhaled corticosteroids used for asthma, if not rinsed away properly after each use, deposit medication around the mouth and increase fungal colonization.
Cold Weather and Environmental Triggers
Angular cheilitis flares tend to cluster in winter months, and the reasons are straightforward. Cold, dry air strips moisture from exposed skin, and the lips are among the most vulnerable areas because they lack the oil glands that protect the rest of the face. Indoor heating compounds the problem by dropping humidity even further. The combination of chapped, cracked lips and increased mouth-breathing due to winter congestion creates the perfect setup for corner-of-mouth fissures.
Extreme weather conditions including dry, hot, or windy climates can also cause or trigger lip inflammation outside of winter.10Acta Dermatovenerologica Alpina Pannonica et Adriatica. Diagnostic management of cheilitis: an approach based on a recent proposal for cheilitis classification If you notice the cracking correlates with seasonal changes or travel to arid locations, environmental exposure is likely a contributing factor. Using a humidifier at home during dry months and applying a protective lip balm before going outside can go a long way.
How to Treat It
Treatment depends on what’s driving the problem, but most cases respond to a few straightforward interventions. The first priority is breaking the moisture cycle by applying a barrier ointment to the corners of the mouth. Petroleum jelly works well and is inexpensive. Zinc oxide paste, the kind used for diaper rash, provides an even thicker barrier and has mild antimicrobial properties. Apply it generously before bed and reapply during the day as needed.
If the cracking is red, swollen, or has whitish patches, a fungal infection is likely involved. Over-the-counter antifungal creams containing clotrimazole or miconazole are the standard first-line treatment. Apply a thin layer to the corners of the mouth two to three times daily for at least two weeks, even if it starts looking better sooner. Stopping early is a common reason for recurrence.
When the lesions look more crusty or yellowish, bacterial infection with S. aureus is more likely. Topical antibiotic ointments like mupirocin can address this, though they typically require a prescription. In cases where both yeast and bacteria are present, your doctor may recommend using an antifungal and an antibacterial together, or a combination product.
For persistent or recurrent cases, management of the underlying cause matters more than the topical treatment:
- Nutritional gaps: Get blood work to check iron, B12, folate, riboflavin, and zinc levels. Supplementation can resolve the issue when a deficiency is confirmed.
- Denture problems: Have your dentist evaluate the fit and vertical dimension of your dentures. Relining or replacing worn dentures can eliminate the anatomical fold that traps saliva.
- Habitual licking: Consciously replace the licking habit with barrier application. For children, gentle reminders and flavored lip balms can help.
- Medication side effects: If isotretinoin or another drying medication is the trigger, aggressive moisturizing and barrier use are essential throughout the course of treatment.
Hydrocortisone cream is sometimes suggested for the inflammation, and a short course (a few days) of a low-strength formulation can help with redness and discomfort. But steroid creams should not be used long-term on the face, as they thin the skin and can actually worsen the problem over time.
When It Might Not Be Angular Cheilitis
Not every crack at the mouth corner is angular cheilitis. Cold sores caused by herpes simplex virus can appear near the lip commissure, and the early cracking stage can look similar. The difference is that cold sores typically start with tingling or burning before visible changes appear, progress through a blistering phase, and tend to recur in the same spot. Angular cheilitis doesn’t blister and is more often bilateral.
Contact dermatitis from lip products, toothpaste ingredients (especially sodium lauryl sulfate or cinnamon flavoring), or musical instruments can also mimic angular cheilitis. If the cracking coincides with a new product, elimination testing is a reasonable approach. Allergic reactions tend to involve more widespread redness and possibly swelling beyond just the corners.
Rarely, persistent unilateral cracking that doesn’t respond to standard treatment can be a sign of something more concerning, such as a precancerous change called actinic cheilitis (from chronic sun exposure) or, very rarely, squamous cell carcinoma. If one corner of your mouth has been cracked for more than a few weeks with no improvement from antifungal and barrier treatment, see a dermatologist or oral medicine specialist. A biopsy is not routinely needed for angular cheilitis, but it becomes appropriate when the presentation is atypical or unresponsive.
Why It Keeps Coming Back
Angular cheilitis has a frustrating tendency to recur, and the reason is usually that the treatment addressed the surface infection without correcting the predisposing condition. The antifungal cream cleared the Candida, but the saliva still pools in that crease every night. The antibacterial ointment healed the fissure, but the worn dentures still reduce the vertical dimension of the face. The barrier ointment protected the skin, but the underlying iron deficiency still makes the tissue fragile.
For people who deal with this repeatedly, an honest inventory of contributing factors is more useful than another tube of antifungal cream. Think about when it flares: is it seasonal, suggesting environmental triggers? Does it follow antibiotic courses, pointing to microbial imbalance? Is it worse when you’re run-down or eating poorly? Addressing angular cheilitis as a multifactorial problem rather than a simple infection is the difference between managing it and actually getting rid of it.5Saudi Journal of Medicine and Public Health. Angular Cheilitis: A Multidisciplinary Approach to Clinical Diagnosis, Nutritional Assessment, Laboratory Evaluation, and Pharmacological Management
Angular Cheilitis in Children
Kids develop angular cheilitis for many of the same reasons adults do, but a few factors are more prominent in younger patients. Lip licking is the most common trigger in children, and the habit can be remarkably persistent.8PubMed Central. Art of prevention: Practical interventions in lip-licking dermatitis Orthodontic appliances and braces can also contribute by altering saliva flow and creating new surfaces where moisture accumulates. Thumb-sucking and pacifier use in younger children keep the mouth corners chronically wet.
Nutritional factors deserve attention in children with recurrent cracking, especially picky eaters. Iron and B vitamin levels are worth checking if the problem comes back despite good topical care. In otherwise healthy children, angular cheilitis is almost never a sign of anything serious, but it can be uncomfortable enough to interfere with eating and should be treated rather than waited out. A thick application of petroleum jelly at bedtime and gentle redirection away from lip licking will resolve most pediatric cases within a week or two.
Saliva, Drooling, and Overnight Flares
Many people notice that angular cheilitis is worst in the morning. This isn’t coincidental. During sleep, you lose conscious control over swallowing and lip positioning. People who sleep with their mouths open, snore, or use CPAP devices for sleep apnea tend to have saliva pooling at the commissures for hours at a time. The prolonged enzyme exposure that results is often enough to initiate or worsen cracking.1International Journal of Dentistry and Oral Science (IJDOS). Angular Cheilitis – An Updated Overview of the Etiology, Diagnosis, and Management
If morning flares are your pattern, the most effective single intervention is applying a generous layer of petroleum jelly or zinc oxide ointment to both corners of the mouth before sleep. This doesn’t stop the saliva from pooling, but it prevents the saliva from contacting and digesting the skin. For CPAP users, checking the mask fit is also worthwhile, as air leaks around the mouth can dry and irritate the commissures. Some people find that using a chin strap to keep the mouth closed during sleep helps, though compliance with yet another sleep device can be a hard sell.