Cracking at the corners of your mouth is almost always a condition called angular cheilitis, an inflammation that develops when moisture gets trapped in the skin folds where your lips meet. It can affect one or both sides, and it tends to stick around (or keep coming back) until the underlying cause is addressed. The cracks may sting, bleed, or crust over, especially when you open your mouth wide to eat or yawn.
What Causes the Cracking
The basic mechanism is straightforward: saliva collects at the corners of your mouth, and that persistent moisture breaks down the skin barrier. Once the skin is damaged, fungi or bacteria move in and make things worse. The most common culprit is Candida, the same type of yeast responsible for oral thrush and vaginal yeast infections. Bacteria, particularly staph species, can also colonize the cracked skin, and in many cases both yeast and bacteria are present at the same time.
What makes this frustrating is that the cracking creates a cycle. The splits hurt, so you lick them. Licking temporarily soothes the irritation but deposits more saliva, which dries and pulls even more moisture out of the skin. The corners stay wet, the skin stays broken, and the infection persists.
Why Saliva Pools at the Corners
Anything that changes the shape of your mouth or increases moisture around it can set the stage. Dentures that don’t fit well are one of the most common triggers, particularly if they cause the lips to fold inward or overlap at the corners. Braces and other orthodontic appliances can have a similar effect. Misaligned teeth that alter your bite may also redirect saliva toward the corners of your mouth.
Age plays a role too. As skin loses elasticity, the corners of the mouth can develop deeper folds where saliva naturally collects. People who drool during sleep are more prone to it, and so are those who habitually lick their lips in dry or cold weather. In children, thumb-sucking and pacifier use are common triggers because they keep the skin around the mouth constantly damp.
Wearing a face mask for extended periods can also contribute by trapping warm, moist air against the skin around your lips.
Nutritional Deficiencies That Play a Role
Sometimes the cracking isn’t about moisture at all. Your body needs certain nutrients to maintain healthy skin and mucous membranes, and when levels drop low enough, the corners of the mouth are often one of the first places to show it.
Iron deficiency is the most well-documented nutritional link. When iron stores are low, the skin and tissues around the mouth become more fragile and slower to heal. B vitamins, particularly B2 (riboflavin), B3 (niacin), B6, and B12, are also essential for skin integrity. A deficiency in any of these can make the corners of your mouth more vulnerable to cracking. Zinc deficiency has a similar effect, since zinc is critical for wound repair and immune function.
If your angular cheilitis keeps coming back despite treating the infection, a nutritional deficiency is worth investigating with a simple blood test. This is especially relevant if you follow a restrictive diet, have heavy menstrual periods (which deplete iron), or have a condition that affects nutrient absorption like celiac disease or Crohn’s.
Underlying Health Conditions
Recurring or stubborn angular cheilitis can sometimes signal a deeper health issue. Diabetes is a significant risk factor because elevated blood sugar impairs immune function and creates an environment where yeast thrives. People with diabetes are more susceptible to Candida overgrowth throughout the body, and the mouth corners are no exception.
Any condition that weakens the immune system raises your risk. This includes HIV, autoimmune disorders, and medications like corticosteroids or chemotherapy that suppress immune activity. Inflammatory bowel disease and other conditions that cause chronic nutrient malabsorption can contribute indirectly by creating the vitamin and mineral deficiencies described above. Down syndrome is another recognized risk factor, partly because it can cause facial skin to be drier and more prone to folding at the mouth corners.
How to Tell It Apart From a Cold Sore
People often confuse angular cheilitis with cold sores (oral herpes), but they look and behave differently. Cold sores typically appear as a cluster of small, fluid-filled blisters on or near the lip, often on the outer lip surface rather than right at the corner. They tingle or burn before the blisters appear, then crust over and heal within about 10 days.
Angular cheilitis, by contrast, shows up specifically at the corners of the mouth. It looks more like a split or raw patch than a blister. The skin may be red, swollen, scaly, or crusty, but you won’t see the grouped, fluid-filled vesicles characteristic of herpes. Angular cheilitis also doesn’t follow a predictable outbreak pattern the way cold sores do. It lingers until the cause is removed, whereas cold sores run their course and resolve on their own.
How It’s Treated
Treatment depends on what’s causing the infection. Since yeast is involved in most cases, a topical antifungal cream applied to the corners of the mouth is the standard first step. If bacteria are also present, your doctor may recommend an antibacterial ointment as well, or a combination product. Most people see improvement within one to two weeks of consistent use.
While treating the infection, protecting the skin from further moisture damage speeds healing. A barrier product like petroleum jelly or zinc oxide paste applied over the corners of the mouth helps seal out saliva. This is especially useful at night if you tend to drool during sleep.
If nutritional deficiencies are contributing, supplementation can resolve the problem, though it may take several weeks for tissue healing to catch up once your levels normalize. For denture-related cases, getting your dentures refitted to eliminate the excess skin folding at the corners often prevents recurrence entirely.
Why It Keeps Coming Back
Angular cheilitis has a reputation for recurring, and there’s usually a reason. If you treat the surface infection but don’t address what’s driving the moisture buildup or immune vulnerability, the same conditions that caused it the first time will cause it again. The most common reasons for recurrence are poorly fitting dentures that never get adjusted, an undiagnosed nutritional deficiency, uncontrolled blood sugar, or a persistent lip-licking habit.
If you’ve had cracking at the corners of your mouth more than two or three times in a year, it’s worth looking beyond the surface. A blood panel checking iron, B vitamins, zinc, and blood glucose can reveal whether something systemic is keeping your skin from holding up at its most vulnerable point.