A sore in the corner of your mouth is most likely angular cheilitis, a common condition caused by moisture buildup, cracking, and sometimes infection at the lip corners. With proper treatment, you can expect improvement within a few days and full healing within about two weeks. Left alone, though, these sores can persist indefinitely or even worsen into painful, bleeding cracks.
The good news is that most cases respond well to simple home care or over-the-counter products. Here’s what’s actually happening at the corners of your mouth, how to treat it, and how to keep it from coming back.
What Causes These Sores
Saliva naturally pools in the creases at the corners of your mouth. When that moisture sits on the skin too long, it breaks down the protective barrier and causes dryness. That might sound contradictory, but constant wetting and drying actually strips the skin of its natural oils. The result is dry, cracked skin that can split open painfully, especially when you eat, yawn, or talk.
Once the skin cracks, fungi (most commonly a yeast called Candida) or bacteria can move into the broken tissue and cause a full infection. This is when a minor annoyance becomes a red, swollen, weeping sore that may bleed when you open your mouth wide. Anything that increases moisture at your lip corners raises your risk: frequent lip licking, drooling during sleep, ill-fitting dentures that change how your lips sit together, braces, or simply having deeper skin folds at the mouth corners.
Nutritional deficiencies account for about 25% of all angular cheilitis cases. Iron deficiency is the most common culprit, followed by several B vitamins: riboflavin (B2), niacin (B3), B6, and B12. If your sores keep returning despite good local care, a nutrient gap may be the underlying driver.
How to Treat It at Home
The core strategy is simple: protect the cracked skin from moisture and give it a chance to heal. If no infection is present (meaning no significant redness, swelling, or oozing), applying a barrier cream like zinc oxide paste or plain petroleum jelly twice a day can be enough. These products sit on the skin’s surface and block saliva from reaching the damaged area, letting the tissue repair itself underneath.
While you’re healing, actively resist the urge to lick the corners of your mouth. Licking feels soothing for a moment but adds more moisture and digestive enzymes to skin that’s already irritated. Keep the area clean and dry, gently patting it rather than rubbing.
If the sore looks infected (red, swollen, crusty, or producing discharge), over-the-counter antifungal creams designed for skin yeast infections can help, since Candida yeast is the most common infectious cause. Apply as directed on the packaging, and continue for the full recommended course even after the sore starts looking better.
When Home Care Isn’t Enough
Most angular cheilitis clears up within two weeks with consistent treatment. If yours hasn’t improved after a week of home care, or if it’s getting worse, a healthcare provider can determine whether you need a prescription-strength antifungal, a topical antibiotic for bacterial infection, or a mild steroid cream to bring down inflammation and pain. Sometimes a combination of these is needed.
Sores that keep recurring despite treatment deserve a closer look. A provider may check for oral thrush (a yeast infection inside the mouth that can seed the lip corners), test your iron and B vitamin levels, or evaluate whether dentures or dental appliances need adjustment. Chronic, untreated angular cheilitis can rarely lead to permanent scarring or skin discoloration at the mouth corners, so persistent cases are worth addressing rather than ignoring.
Is It a Cold Sore or Angular Cheilitis?
These two conditions look similar enough that people confuse them constantly, but they’re different problems with different treatments. Cold sores are caused by the herpes simplex virus. They typically start as an itchy or tingling spot that develops into one or more small blisters, which eventually weep, scab over, and heal. Cold sores can appear anywhere around the lips, not just the corners.
Angular cheilitis starts as a patch of dry, irritated, or cracked skin specifically at one or both corners of the mouth. There are no fluid-filled blisters. It progresses into deeper cracks and swollen sores if untreated, and it tends to hurt most when you open your mouth wide. If you’re seeing blisters, you’re likely dealing with a cold sore, which requires antiviral treatment rather than antifungal or antibacterial care.
Preventing It From Coming Back
Once you’ve healed, prevention comes down to keeping the mouth corners dry and the skin barrier intact. A thin layer of petroleum jelly at bedtime can protect against overnight drool. If you wear dentures, make sure they fit properly, since gaps between the denture and gums change the way your lips close and can create deeper folds where saliva collects. Clean dentures thoroughly each night.
If nutritional deficiency is a factor, addressing it makes a real difference. Iron-rich foods (red meat, lentils, spinach, fortified cereals) and B vitamin sources (eggs, dairy, whole grains, leafy greens) can help correct mild deficiencies over time. For confirmed deficiencies, a supplement may resolve the issue faster. Cold, dry weather also increases risk by drying out lip skin, so a good lip balm during winter months adds another layer of protection.
Pay attention to any habits that funnel moisture to the lip corners. Thumb-sucking in children, habitual lip licking, and even using a straw frequently can all contribute. Breaking the moisture cycle is the single most effective thing you can do to keep angular cheilitis from returning.