Angular Cheilitis: Why the Corners of Your Mouth Crack, and How to Actually Treat It

Chapped lips heal with balm in a day or two. A crack right at the corner of the mouth that keeps splitting, stings when you open wide, and does not respond to lip balm at all is usually something else — angular cheilitis, an inflammation of the skin folds at the mouth's corners that has a specific, treatable cause underneath.

Why It Happens

The corners of the mouth form a natural skin fold that traps saliva, creating a warm, moist environment where the yeast Candida albicans or certain bacteria (commonly Staphylococcus aureus) can overgrow. Once the skin cracks, these organisms move in and keep the area irritated in a cycle that will not resolve until the underlying infection is treated, not just moisturised.

What Makes Someone More Prone to It

• Ill-fitting dentures: Dentures that have lost vertical height (often from wear over years) let the corners of the mouth fold inward more deeply, creating a deeper, more constantly moist crease.
• Excess saliva pooling: Habitual lip-licking, drooling during sleep, or braces that cause the lips to not seal fully all keep the corners persistently damp.
• Nutritional deficiencies: Low iron, B2 (riboflavin), B12, or folate can impair the skin's ability to heal and are a recognised contributing factor, particularly in recurring or hard-to-treat cases.
• Immune-suppressing conditions: Diabetes, or medication that suppresses the immune system, can make fungal overgrowth more likely.
• Dry, cold weather: Simply cracks the skin at the corners in the first place, giving organisms an entry point.

How It's Diagnosed

Usually a visual diagnosis based on the characteristic cracking, redness, and sometimes crusting at the mouth's corners. If it is recurrent or not responding to standard treatment, a dentist or doctor may take a swab to identify whether Candida or a bacterial species is the dominant cause, and may order a blood test to check for an underlying vitamin or iron deficiency.

What Actually Treats It

• Antifungal cream: Since Candida is the most common cause, an over-the-counter or prescription antifungal cream (such as clotrimazole or miconazole) applied to the corners is usually the first-line treatment.
• Antibacterial cream: If a bacterial cause is identified or suspected, a topical antibiotic (such as fusidic acid or mupirocin) may be prescribed instead or alongside the antifungal.
• Combination steroid creams: A short course of a mild topical steroid combined with an antifungal/antibacterial can reduce inflammation faster in more severe cases, under a dentist's or doctor's guidance.
• Correcting the underlying cause: A denture reline or replacement if fit is the issue, or iron/B-vitamin supplementation if a deficiency is confirmed — without this, cream alone often leads to the condition returning.

What to Avoid

Licking the corners of the mouth to "soothe" them keeps the area moist and worsens the cycle rather than helping. Petroleum jelly alone can sometimes trap moisture against the skin rather than letting it heal, so it is better used as a protective barrier after treating the underlying cause, not instead of it.

When to See a Dentist or Doctor

If it has not improved within a week of basic care, keeps coming back, or is accompanied by other symptoms like mouth soreness, a swollen tongue, or fatigue (which can point to a vitamin deficiency), it is worth getting checked rather than continuing to self-treat with lip balm.