Your lips can become chapped and dry when they're exposed to the sun, wind or cold air. A lip balm containing petroleum or beeswax will provide a barrier and help seal in moisture.
More moisture is lost through the lips than through any other part of the face or body.
When the lips lose moisture, the skin covering them can become tight and start to split.
What not to do
It's very tempting to pick and bite off flakes of dried skin, but this will only make your lips bleed and heal more slowly. Irritating the skin around your mouth may also trigger a cold sore if you're prone to getting them.
It's also tempting to keep licking dry or cracked lips. But this will only dry your lips more, as the saliva evaporates and the repeated licking or wetting "washes" the natural grease off the skin.
How to treat dry or sore lips
The best thing to do if you have dry or sore lips is to regularly apply a lip balm containing petroleum or beeswax. You may need to try a few different products before you find one that works for you.
For example, you may be sensitive to fragranced products, in which case non-fragranced lip balms are available.
If you're going to be spending time outdoors in the sun, choose a lip balm with a sun protection factor (SPF) of at least 15 to help protect your lips.
Lip balm acts as a shield to protect your lips against the sun, wind and cold or dry air. It will trap moisture and seal cracks against infection.
Avoid lip balms in pots – repeatedly dipping your finger into the balm can introduce germs.
Covering your lips with a scarf when you're outside during the winter can also help prevent dry lips.
When dry lips become inflamed
Sometimes dry lips can become inflamed and feel sore. The medical term for inflamed lips is cheilitis.
Lips usually become inflamed as a result of mild irritation. They can also become inflamed if they're infected with bacteria or fungi that have entered cracks in the skin of the lips.
If the corners of your mouth are red and sore, you may have a type of inflammation called angular cheilitis. This is often caused by bacteria or fungi and is treated with ointments applied to the area.
Angular cheilitis can sometimes be a symptom of a type of eczema called contact dermatitis, and is more common in people who wear dentures.
It's also more common in older people – with age, the creases around the corners of the mouth become more pronounced, and saliva can build up in the crevices and irritate the skin.
When to see your GP
See your GP if your lips are red and sore and you think they're infected. They may prescribe an antibiotic or antifungal cream to treat the infection. This may also contain 1% hydrocortisone (steroid medication) to reduce the inflammation.
If you have a non-healing persistent sore, this should be seen by your GP as soon as possible.