Red, irritated corners of the mouth are almost always a condition called angular cheilitis. It happens when moisture collects in the creases where your lips meet, creating the perfect environment for yeast or bacteria to grow. The result is redness, cracking, and sometimes painful splits that can linger for days or weeks if the underlying cause isn’t addressed.
What Angular Cheilitis Looks and Feels Like
The redness typically appears on one or both corners of the mouth, right in the crease. In mild cases it just looks like a patch of irritated skin. As it progresses, you may notice small cracks or fissures forming, a burning or stinging sensation when you open your mouth wide, and dry, flaky skin at the edges. Some people develop a slight crust or whitish buildup in the creases. Eating acidic or salty foods often makes it sting.
It’s easy to confuse angular cheilitis with a cold sore, but they’re quite different. Cold sores are caused by the herpes virus and usually appear as a cluster of tiny blisters on or near the lip itself, not tucked into the corner crease. Angular cheilitis stays right at the commissure (the point where upper and lower lips meet) and doesn’t blister.
Moisture and Infection: The Main Cause
The corners of your mouth are a natural collection point for saliva. When moisture sits in those creases repeatedly, the skin breaks down and becomes vulnerable to infection. The most common culprit is Candida, a yeast that already lives in your mouth and on your skin. Bacteria, particularly staph, can also move in. Often both are present at the same time, which is why angular cheilitis can be stubborn to treat with a single approach.
Anything that increases moisture buildup raises your risk. Lip licking is one of the most common triggers. It feels like it should help the dryness, but saliva evaporates quickly and takes moisture from the skin with it, leaving the area more irritated and more prone to cracking. Children who suck their thumbs or use pacifiers frequently develop angular cheilitis for the same reason.
Dentures, Braces, and Facial Structure
Dental appliances are a major risk factor. Ill-fitting dentures can change the way your lips rest, creating deeper folds at the corners where saliva pools. People who have lost teeth and haven’t replaced them may experience a similar effect because the lower face loses vertical height, which deepens the mouth creases. Braces and retainers can also contribute by increasing saliva production or redirecting its flow.
People who wear masks for extended periods as part of their job face higher rates of angular cheilitis too, because the mask traps heat and moisture around the mouth. Even habits that seem unrelated, like excessive mouth washing or aggressive flossing, can irritate the area enough to trigger an episode.
Nutritional Deficiencies That Cause It
If your angular cheilitis keeps coming back or doesn’t respond to topical treatment, a nutritional deficiency may be the underlying driver. Several B vitamins, iron, and zinc are directly linked to this condition.
- Vitamin B2 (riboflavin): One of the most strongly associated deficiencies. Low B2 causes cracked lips, mouth corner inflammation, and a swollen, reddish-purple tongue. It can also impair iron absorption, compounding the problem.
- Vitamin B3 (niacin): Severe deficiency causes angular cheilitis alongside skin rashes, digestive problems, and in extreme cases, cognitive changes.
- Vitamin B6: Deficiency can show up as mouth corner cracks along with mouth ulcers, a smooth or swollen tongue, and sometimes nerve-related symptoms like tingling in the hands.
- Folate and B12: Both can cause angular cheilitis, often alongside fatigue and a sore tongue. B12 deficiency is particularly common in vegetarians and older adults.
- Iron: Low iron produces angular cheilitis together with fatigue, pale skin, and sometimes spoon-shaped nails. In more advanced cases, difficulty swallowing can develop.
- Zinc: Deficiency shows up as mouth corner cracks, hair thinning, skin rashes, and diarrhea.
These deficiencies don’t always come with dramatic symptoms. You might feel mostly fine but still have levels low enough to weaken the skin at the mouth corners. If you follow a restricted diet, have heavy periods, or have a condition that affects nutrient absorption (like celiac disease or Crohn’s disease), a blood test checking these levels is worth pursuing if your angular cheilitis keeps returning.
Other Health Conditions Linked to It
Diabetes increases susceptibility to angular cheilitis because elevated blood sugar promotes yeast overgrowth and slows skin healing. People with weakened immune systems, whether from medication or illness, are also more prone to persistent or recurring cases. Inflammatory bowel diseases like Crohn’s can cause angular cheilitis both through nutrient malabsorption and as a direct manifestation of the disease itself. Protein malnutrition, even when it’s subclinical, is another recognized trigger.
How to Treat It
Treatment depends on what’s causing the infection. Since yeast is involved in most cases, an over-the-counter antifungal cream applied to the corners of the mouth several times a day is the standard starting point. Look for creams containing clotrimazole or miconazole, both widely available at pharmacies. Apply a thin layer to the affected area after meals and before bed.
If bacteria are also involved, which is more likely if the area looks crusted or weepy rather than just red and cracked, a topical antibiotic may be needed alongside the antifungal. Your doctor can determine this with a quick visual exam or, in persistent cases, a swab.
While treating the infection, keeping the area dry and protected speeds healing. A thin layer of petroleum jelly or a zinc oxide barrier cream over the corners of your mouth prevents saliva from re-irritating the skin. This is especially helpful at night, when drooling during sleep can undo a day’s progress.
Stopping It From Coming Back
Breaking the moisture cycle is the most important preventive step. If you catch yourself licking your lips frequently, switching to a fragrance-free lip balm or petroleum jelly throughout the day helps reduce the urge. Apply it to the corners specifically, not just the lips themselves.
If you wear dentures, making sure they fit properly is critical. Dentures that are too small or too old can collapse the bite, deepening the mouth corner creases and creating a permanent moisture trap. A dental checkup to evaluate fit can resolve cases that no amount of cream will fix.
For nutritional causes, correcting the deficiency usually resolves angular cheilitis completely, though it can take a few weeks for the skin to fully heal after levels normalize. Foods rich in B vitamins (meat, eggs, dairy, leafy greens, legumes), iron (red meat, spinach, fortified cereals), and zinc (shellfish, seeds, nuts) support the skin’s integrity at the mouth corners. If a blood test confirms a deficiency, a targeted supplement works faster than dietary changes alone.
Cold, dry weather and wind exposure can also trigger flare-ups by drying and cracking the skin. Applying a barrier product to the mouth corners before heading outside in winter offers a simple layer of protection that makes a noticeable difference for people prone to recurrences.