Lip inflammation, known medically as cheilitis, has a surprisingly wide range of causes, from something as simple as a reaction to your lip balm to nutritional deficiencies or sun damage. Your lips are uniquely vulnerable because, unlike the rest of your face, the outer lip tissue has no oil or sweat glands. It relies entirely on external moisture sources, which makes it thinner, more exposed, and quicker to react when something goes wrong.
Allergic Reactions to Lip Products
One of the most common reasons for inflamed lips is contact with an ingredient your skin doesn’t tolerate. This is called allergic contact cheilitis, and it often catches people off guard because the offending product may be one you’ve used for months or years. Allergies can develop over time with repeated exposure.
Lip balms, lipsticks, and glosses contain a long list of potential irritants. Research published in the Journal of Cutaneous Medicine and Surgery identified several common triggers found in lip balm ingredients: fragrances (especially limonene and eugenol), propolis (a beeswax derivative popular in “natural” products), peppermint oil, and sunscreen agents. Toothpaste flavoring, particularly cinnamon, is another frequent culprit. Even mouthwash or certain foods can trigger a reaction on lip tissue that wouldn’t bother skin elsewhere on your body.
If your lips are red, peeling, or burning and you recently switched products, or even started a new toothpaste, that’s worth investigating. The simplest test is to strip your routine down to plain petroleum jelly for a week or two and see if things improve. If they do, reintroduce products one at a time to identify the trigger.
Cracked Corners of the Mouth
If the inflammation is concentrated at the corners of your mouth rather than across the full lip, you’re likely dealing with angular cheilitis. This starts as small cracks or splits at the corners that become red, sore, and sometimes crusty. Saliva pools in those creases, creating a warm, moist environment where bacteria and fungi (especially yeast like Candida) thrive. The cracks get infected, the infection causes more cracking, and the cycle continues.
Several things raise your risk. People who drool during sleep, wear ill-fitting dentures, or habitually lick their lips are more prone. Nutritional deficiencies also play a role: low levels of B vitamins, iron, or protein can weaken the skin at the mouth corners enough to trigger the cycle. If you get angular cheilitis repeatedly, it’s worth having your blood levels checked. A B-complex supplement can sometimes resolve the issue within days if a deficiency is the root cause.
Sun Damage on the Lips
Chronic sun exposure causes a specific type of lip inflammation called actinic cheilitis. It almost always affects the lower lip, which faces upward toward the sun. The lip may look persistently dry, scaly, or pale, with blurred borders where the lip meets the surrounding skin. Some people notice rough patches that don’t heal or a gritty texture on the lip surface.
This one matters because it’s precancerous. Actinic cheilitis progresses to squamous cell carcinoma in 6% to 10% of cases. People with a history of significant outdoor work, light skin, or years of unprotected sun exposure are most at risk. If you have a persistent scaly or rough patch on your lower lip that doesn’t resolve with moisturizing, getting it evaluated is important. A biopsy can determine whether the cells have started to change.
Prevention is straightforward: use a lip balm with SPF 30 or higher, and reapply it as often as you would sunscreen on your face.
Eczema on the Lips
If you already have eczema elsewhere on your body, your lips can develop it too. Eczematous cheilitis causes dry, flaky, irritated lips that may crack and peel in cycles. It can also appear as an isolated allergic reaction in people who don’t have eczema elsewhere, triggered by contact with irritating substances.
The distinction matters because eczema-related lip inflammation tends to be chronic and relapsing. Keeping the lip barrier intact with a thick, fragrance-free ointment like petroleum jelly is the foundation of management. It prevents moisture loss and creates a protective seal over the damaged skin. For flares that don’t settle on their own, prescription options include anti-inflammatory ointments that calm the immune response in the skin without the side effects of long-term steroid use.
Infections: Cold Sores and Bacterial Causes
Infective cheilitis is caused by either the herpes simplex virus (cold sores) or bacterial infections like group A strep. Cold sores are by far the more common culprit. They typically start with a tingling or burning sensation before small fluid-filled blisters appear, usually on or near the lip border. The blisters break open, crust over, and heal within one to two weeks.
Bacterial lip infections are less common but can develop when cracked or broken lip skin allows bacteria to enter. This tends to produce more uniform redness, swelling, and sometimes pus rather than the clustered blisters of a cold sore. Both types are contagious during active infection.
Autoimmune Conditions
Less commonly, lip inflammation is driven by the immune system attacking the tissue itself. Oral lichen planus is one such condition. It causes ongoing inflammation of the mucous membranes in the mouth, including the inner lip tissue. The erosive form produces red, swollen patches or open sores that burn, especially when eating hot, acidic, or spicy foods. A lacy white pattern on the inside of the cheeks is a telltale sign, though it can appear on the gums, tongue, and inner lips as well.
Granulomatous cheilitis is a rarer autoimmune-related condition that causes persistent swelling and lumps under the lip skin. The swelling can affect the upper lip, lower lip, or both, and sometimes spreads to the cheeks. The lumps are benign, but the swelling tends to recur and can become permanent without treatment. This condition is sometimes linked to Crohn’s disease or other systemic inflammatory conditions.
Nutritional Deficiencies
Your lips can act as an early warning system for what’s missing in your diet. B vitamin deficiencies are the most well-known cause of lip cracking and inflammation. Riboflavin (B2) and niacin (B3) deficiencies in particular target the lips and mouth corners. Iron deficiency can cause similar symptoms, sometimes accompanied by a sore, swollen tongue.
These deficiencies are more common in people with restrictive diets, heavy alcohol use, or conditions that impair nutrient absorption like celiac disease. If your lip inflammation is accompanied by fatigue, pale skin, or mouth sores, a simple blood test can check for the most likely nutritional gaps.
What Helps Inflamed Lips Heal
Regardless of the underlying cause, protecting the lip barrier is the first step. Petroleum jelly is the single most effective over-the-counter option. It locks in moisture and prevents the constant cycle of drying and cracking that keeps inflammation going. Apply it several times a day, especially before bed and before going outdoors.
Beyond that, treatment depends entirely on the cause. Allergic reactions resolve once the trigger is removed. Angular cheilitis caused by yeast or bacteria needs an antifungal or antibiotic cream. Nutritional deficiencies respond to supplementation, sometimes within days. Sun-damaged lips need ongoing UV protection and possibly a procedure to remove precancerous tissue. Autoimmune-driven inflammation typically requires prescription anti-inflammatory treatments applied directly to the affected area.
One habit worth breaking: licking your lips. Saliva evaporates quickly and strips away what little natural moisture the lip tissue holds, making inflammation worse. If you notice yourself doing it, applying a layer of petroleum jelly gives your lips something protective instead.