Cracked corners of the mouth are almost always caused by a condition called angular cheilitis, where saliva pools at the edges of the lips, dries out the skin, and creates small fissures that can become infected with fungus or bacteria. It’s common, usually not serious, and highly treatable once you understand what’s driving it.
The corners of your mouth are uniquely vulnerable because two different types of skin meet there: the moist lining inside your mouth and the regular skin of your face. This junction works like a hinge, opening and closing constantly as you eat, talk, and drink. That mechanical stress, combined with trapped moisture, makes the area prone to breakdown.
How Saliva Starts the Problem
The most common trigger is simple: saliva collects in the creases at the corners of your mouth and sits there. Rather than keeping the skin moist, saliva actually dries it out as it evaporates, because it contains digestive enzymes that irritate and strip the skin’s protective barrier. Over time, the skin becomes so dry it cracks open. Once cracks form, fungi (usually Candida, the same organism behind thrush and yeast infections) or bacteria like Staphylococcus aureus can move in, turning a minor irritation into a persistent, inflamed sore.
This is why licking your lips makes the problem worse. It feels soothing in the moment, but it reintroduces saliva and digestive enzymes to already-damaged skin, restarting the cycle of moisture, dryness, cracking, and infection.
Nutritional Deficiencies That Play a Role
If cracked mouth corners keep coming back or appear without an obvious cause, a nutritional deficiency may be involved. The most common culprits are iron, zinc, and several B vitamins.
Iron deficiency is one of the most frequent nutritional causes. Low iron can trigger cracking and inflammation at one or both corners of the mouth, and you may also notice pale skin, brittle nails, and unusual fatigue.
Zinc deficiency causes dryness and irritation at the mouth corners along with broader symptoms like decreased immunity, skin ulcers, diarrhea, and hair loss.
B vitamin deficiencies, particularly riboflavin (B2), B6, B12, and folate (B9), are well-established causes of cracked lips and angular cheilitis. These deficiencies can also produce skin inflammation elsewhere on the body, along with fatigue, irritability, and depression. People on restrictive diets, those with absorption issues, and older adults are especially susceptible.
Dental Appliances and Facial Structure
Ill-fitting dentures are a major risk factor. When dentures don’t sit properly, they change the way your face folds around the mouth, creating deeper creases where saliva can pool. Gum recession makes this worse by altering the overall contour of the lower face. Getting dentures properly fitted or replaced often resolves the problem entirely.
Facial anatomy plays a role even without dentures. People who have a set-back jaw position or naturally deep folds running down from the corners of the mouth (sometimes called marionette lines) are more prone to saliva trapping. As skin loses elasticity with age, these folds deepen, which is one reason angular cheilitis becomes more common in older adults.
Medical Conditions That Increase Risk
Certain health conditions make cracked mouth corners more likely. Diabetes is one of the most important, because elevated blood sugar promotes fungal overgrowth and impairs skin healing. HIV and other conditions that weaken the immune system also increase susceptibility to the Candida infections that drive many cases of angular cheilitis.
Sjögren syndrome, an autoimmune condition that reduces saliva and tear production, can paradoxically contribute by causing dry mouth that leads to compensatory lip licking. Inflammatory bowel diseases may play a role through nutrient malabsorption, particularly of iron and B vitamins.
Contact allergies are another overlooked cause. Metals in dental appliances, flavorings in toothpaste or food, and preservatives in lip cosmetics can all trigger an allergic reaction that presents as angular cheilitis. If cracks appeared after you switched toothpaste, started wearing new dental hardware, or began using a new lip product, an allergic reaction is worth considering.
How to Tell It Apart From Cold Sores
Cracked mouth corners and cold sores can look similar at first glance, but they behave differently. Angular cheilitis produces dry, cracked, crusty skin that may bleed. It stays at the corners of the mouth, sometimes extending slightly onto the surrounding skin. Cold sores, by contrast, are fluid-filled blisters that look wet or bubbly and tend to cluster on the lips, around the mouth, or even near the nose. On lighter skin, cold sore blisters appear red or pink; on darker skin, they often look brown or purple.
The progression is different too. Cold sores start with tingling or itching, develop into weeping blisters, then scab over and heal. Angular cheilitis starts as dryness, progresses to cracking, and can persist for weeks or months if the underlying cause isn’t addressed. Cold sores are caused by the herpes simplex virus and are contagious; angular cheilitis is not contagious.
Treatment and Recovery
Treatment depends on what’s causing the problem. When a fungal infection is involved, a topical antifungal cream applied to the corners of the mouth clears most cases. Bacterial infections require a topical antibiotic instead. In many cases, both organisms are present, so a combination approach works best. Your doctor or dentist can usually diagnose the cause by examining the area and, if needed, taking a swab.
While treating the infection, protecting the skin from further moisture damage is essential. A barrier product like petroleum jelly or zinc oxide ointment applied to the corners of your mouth keeps saliva from pooling in the creases. This is especially useful at night, when drooling during sleep can worsen the condition.
With the right treatment, mild cases often improve within a couple of weeks. More stubborn or recurrent cases usually signal an underlying issue: a nutritional deficiency that needs correcting, dentures that need refitting, or a medical condition that needs managing. Addressing the root cause is the only way to keep angular cheilitis from coming back.
Preventing Recurrence
Breaking the licking habit is the single most impactful thing you can do if you’re prone to cracked mouth corners. Replace the urge to lick with a thick lip balm or ointment that creates a physical barrier. Keep it within reach so you always have an alternative.
If you wear dentures, have them checked regularly for fit. Even small changes in gum tissue over time can create the kind of gaps and folds that trap saliva. For people with naturally deep facial creases, consistently applying a barrier ointment to the corners of the mouth before bed can prevent overnight saliva damage.
Diet matters too. Making sure you get adequate iron, zinc, and B vitamins through food or supplements addresses one of the most common underlying causes. Iron-rich foods include red meat, lentils, and spinach. Zinc is found in shellfish, seeds, and nuts. B vitamins come from whole grains, eggs, dairy, and leafy greens. If you eat a varied diet and still develop angular cheilitis repeatedly, blood work can reveal whether a specific deficiency is at play.