Cracked, sore corners of my mouth: what sets it off?

A 2023 study from the University of Zagreb in Croatia found that people who said saliva collected at the corners of their mouth had cracks there more often, and dermatologists explain that licking dry lips keeps the dryness going. In older denture wearers, cracked corners were linked with dentures that were not stable. The UK's NHS lists cold weather, dry air or wind, sun and allergies among common causes of sore or dry lips. For everyday care, the NHS advises not to keep licking your lips, to use a lip balm, and to see a dentist if dentures slip.

Why do the corners of my mouth crack?

The studies below point to a few everyday factors linked with redness and cracks at the corners of the mouth.

What it looks like

A 2011 review by dermatologists in the United States describes the problem as redness, moist softened skin, open sores and crusting at the corners of the mouth, and calls it common. It explains that several local factors can act alone or together, and groups them as irritation, allergy and germs.

How common it is

A 2024 review by dermatologists in Europe notes two age peaks, one in childhood and one in adulthood, and that cracked corners become more frequent with age.

Everyday triggers

How does licking my lips make it worse?

It feels soothing for a moment, but it adds to the problem.

What the NHS says

The UK's NHS advice on sore or dry lips says not to keep licking dry or cracked lips, because this can make them sore, and not to pick or bite any flaky skin, because this can slow down healing.

Why the habit keeps going

A 2020 article by US dermatologists Fonseca, Jacob and Sindle explains that licking is a way people try to make dry, cracked lips feel better, but that it keeps the dryness going. When it becomes a long-term habit, it can lead to further problems, including at the corners of the mouth. They recommend a bland lip balm with UV protection, enough to drink, protecting the lips from harsh weather, and recognising when it is time to see a dermatologist.

Saliva at the corners

The Croatian study by Blagec and colleagues looked at 130 people with sore lips and 22 people without. People who said saliva collected at the corners of their mouth were significantly more likely to have cracks there. Habits were self-reported and the people were seen at a university hospital, so the study shows a link rather than a cause.

Why does it happen more with dentures or with age?

The NHS notes that the mouth changes shape with age, which can make dentures loose. Studies of older denture wearers found cracked corners among the most common denture-related problems.

What studies of denture wearers found

The Thai study, by Jainkittivong and colleagues at Chulalongkorn University, examined the mouths of 500 Thai adults aged 60 and over attending dental care. Denture wearers showed mouth problems far more often than people without dentures.

The Spanish study from the University of Barcelona found that cracked corners in denture wearers were linked with:

• older age
• having no natural teeth left
• dentures that were not stable
• a reduced bite height, meaning the jaws close further together than they should

Both studies looked at older people attending dental care or living in care settings, so the figures do not describe all older adults.

Looking after dentures

The NHS advice on dentures says to remove dentures every night, to brush them with soft soap or washing-up liquid every morning and evening rather than toothpaste, and to keep seeing a dentist regularly. Dentures can become loose as the mouth changes shape with age. See a dentist if they slip, no longer fit properly, or are worn or damaged.

Can weather, sun or a face mask play a part?

Yes, for the lips in general.

Weather and sun

The NHS lists cold weather, dry air or wind, damage from the sun, dehydration, a lip injury and allergies among the common causes of sore or dry lips. The NHS adds that dry or sore lips are a common problem, especially during hot or cold weather.

Face masks

A 2020 survey in Thailand by Khon Kaen University found that 54.5% of people wearing face masks reported a skin problem under the mask, most often spots (39.9%), then rashes (18.4%) and itching (15.6%). Wearing a mask for more than 4 hours a day and reusing masks were linked with more problems than changing the mask every day. The study did not look at the corners of the mouth specifically.

What can I do about it day to day?

The NHS advice for sore or dry lips gives a simple list.

If you wear dentures, the NHS advises taking them out every night, cleaning them every morning and evening, seeing a dentist regularly, and going back to the dentist if they slip or no longer fit.

For sensitive, easily irritated skin in general, see Sensitive, easily irritated skin: how do you care for it?

When should I see a doctor, dentist or pharmacist?

A pharmacist can advise you about the best treatments for dry or sore lips, and whether you need to see a GP, as the NHS notes.