Cold weather, drying air-conditioning and dehydration can all cause chapped lips, but there are more surprising culprits at play. Your lips don’t contain oil glands like the rest of your face (and body) so they can’t re-hydrate or protect themselves.
Putting toothpaste chemicals on your lips at least twice per day is doing no favours for your lips. More specifically, sodium laurel sulphate (SLS) is the culprit here. SLS is a common detergent, found in everything from laundry liquid to shampoo, and it makes things nice and foamy. Although the quantities are small in toothpaste, and you're advised not to ingest it, toothpaste still gets on your lips and can cause them to dry out because it strips the oil from your skin. This cleaning ability makes it great for use in dish washing liquid, but not for your delicate skin.
"People do occasionally develop hypersensitivity to toothpaste that can lead to a chapped appearance,” Dr Neil Sadick, a clinical professor of dermatology at Weill Cornell Medical College in New York explained to Seventeen.com. “Sometimes there's an allergy to sodium laureate sulphate or to a component called cinnamaldehyde."
Some lip balms contain petroleum jelly, which is created from crude oil and refined to create the clear gel we're familiar with today. It's insoluble in water, water repellent and very cheap to produce. As it's a humectant (meaning it draws water up from the lower levels of your skin) it only gives the illusion of moisturising dry or chapped lips. Once the water is drawn up to the petroleum jelly sitting on your lips, it can then evaporate. These lips balms don't contain any healing properties, force you to constantly reapply to get that hydrated feeling and can even leave your lips feeling worse after prolonged use.
Chapped lips might be a sign that you're deficient in certain vitamins, such B2 and B6. Vitamin B2 is important for cell function, the metabolism of fats and can help the body protect against infection – all of which are vital for maintaining the skin's barrier. Being low in B2 can result in swollen and cracked lips, so you should eat vitamin B2-rich foods such as almonds, eggs and mushrooms, to increase your levels. Cracked lip corners can also mean a vitamin B6 deficiency. Add in extra chickpeas, tuna and potatoes to your diet to boost your diet of this vitamin, and help repair your lips.
Your lips are a commonly missed place when applying sunscreen and are easily susceptible to burn, even if you don’t notice it. Sunscreen can also be rubbed off with eating and drinking, or missed entirely when reapplying. Sunburnt lips, like any burn, can be dry and dehydrated causing the skin to crack and flake. Even if your lips don’t show signs of being burnt, you should be protecting them with a SPF lip balm during the day, and using a cream rich in ceramides at night can help restore the skin's barrier to restore suppleness.
Citrus fruits are highly acidic, which can damage the layers of skin on your lips by chemically burning them. Although this sounds scary, the levels of acid in the fruit isn't high enough to cause permanent damage, but it might sting or inflame the delicate skin. The high acidity can also irritate existing chapped lips, causing more flaking and pain.