Lip Sores: Causes, What to Apply and How Many Days Until They Heal
Updated: 5 days ago
A lip sore (cheilitis) is when the skin of the lips or the lip border cracks, peels, forms blisters or opens into a sore. It can come from several conditions that look alike. The most common causes are dry cracked lips from weather or lip licking, cold sores (herpes labialis), angular cheilitis (sores at the corners of the mouth), canker sores (aphthous ulcers) on the inside of the lip, and allergy to things that touch the lips. Most heal within 7–14 days, but a lip sore that does not heal after 3 weeks must always be examined by a doctor.
The medicines that help each type of sore are very different. Antivirals help cold sores but not dry cracked lips. Antifungals help angular cheilitis but not canker sores. And steroid creams that help an allergic rash can make a cold sore spread. This article therefore separates lip sores one by one by location and appearance, and explains how to tell them apart by eye, the medicines doctors use, strengths, duration, and the warning signs that need prompt examination.
Check where the sore is first: it narrows down the cause a lot
The lips have 3 areas where different diseases occur, so checking where the sore is located is the first step dermatologists use.
Lip border (the line between the lips and the facial skin): a cluster of clear blisters that then crust over is usually a cold sore. A red, peeling ring of rash around the lip border is usually a rash from lip licking or from an allergy.
Red part of the lip (where lipstick is applied): dryness, cracking, peeling in sheets, or a crack in the middle of the lip is usually dry cracked lips, chronic lip peeling, or lipstick allergy. Chronic changes on the lower lip in someone with a lot of sun exposure should raise the possibility of actinic cheilitis (sun damage of the lip).
Corners of the mouth: redness, soggy skin or cracks at one or both corners are usually angular cheilitis.
Inside of the lip (the moist lining): a shallow round sore that is white-yellow with a red edge is usually a canker sore. A soft, raised, clear fluid-filled bump on the inside of the lower lip is usually a mucus cyst from lip biting.
Timing also helps tell them apart. Cold sores and canker sores heal on their own in 7–14 days, and dry cracked lips improve in 3–7 days with proper care. A sore that lasts more than 3 weeks, feels hard, or bleeds easily should not be left to wait.
Cold sores on the lip (herpes labialis)
Appearance: before anything is visible, you feel tingling, burning or itching at the same spot for 6–24 hours. Then clusters of clear blisters 1–3 millimetres wide appear on a red base, usually at the lip border. Within 2–3 days the blisters burst into shallow sores, then form a yellow or brown crust and heal within 7–10 days without scarring. It often returns at the same spot.
Cause: the herpes simplex virus (mostly type 1), which stays dormant in nerve cells after the first infection and flares up when triggered by things such as strong sunlight, fever or a cold, lack of sleep, stress, menstruation, or dental work and procedures around the mouth.
Severity/urgency: mostly not dangerous and heals on its own, but it is contagious from the tingling stage until the crust falls off. So avoid kissing, sharing cups or lip products, and avoid kissing babies or people with chronic eczema during this time.
When to see a doctor: if it is the first episode with fever and several sores in the mouth, if the sore spreads or has not healed in 2 weeks, if it recurs more than 6 times a year, if there are eye symptoms, or if the immune system is weak.
Details about recurrences and prevention are in the articles Cold sores: how many days to heal and which medicine works and What causes herpes.
Dry cracked lips and dry, sore lip border (cheilitis simplex)
Appearance: the lips are dry, tight, flaky and split into many small cracks. Sometimes there is a deep crack in the middle of the lower lip that oozes blood when you smile or open wide, and it stings with spicy or salty food. Usually both upper and lower lips are affected, with no blisters.
Cause: cold weather and low humidity in winter, air-conditioned rooms, mouth breathing, drinking too little water, and most commonly lip licking, which keeps the lips moist for only a few seconds before the saliva evaporates and pulls out even more moisture.
Severity/urgency: not dangerous. It improves in 3–7 days once you stop licking your lips and apply a protective barrier regularly.
When to see a doctor: if there is no improvement after 2 weeks of using petroleum jelly correctly, if the crack in the middle of the lip returns every year, or if the lips keep peeling in sheets for a month.
Read about every cause of dry, peeling lips in Dry peeling lips and cracked lips: what causes them.
Red rash around the lip border from lip licking (lip licker's dermatitis)
Image: James Heilman, MD · CC BY-SA 4.0 · edited
Appearance: a red, dry, peeling ring of rash with a sharp edge around the lips, 5–15 millimetres wide, matching the area the tongue reaches. It sometimes cracks and stings. It is common in school-age children and in winter.
Cause: saliva contains digestive enzymes that irritate the skin. Licking repeatedly dozens of times a day inflames the skin around the mouth, and the drier it gets the more you want to lick, creating a cycle.
Severity/urgency: not dangerous, but it will not clear while the licking continues.
When to see a doctor: if there is no improvement after 2 weeks of stopping the licking and applying a barrier, if there are pustules or honey-yellow crusts, which may mean a secondary bacterial infection, or if the child has eczema elsewhere too.
Angular cheilitis, sores at the corners of the mouth
Image: Matthew Ferguson 57 · CC BY-SA 3.0 · edited
Appearance: red, soggy, cracked corners of the mouth, sometimes with a white coating, painful when opening the mouth. It can affect one or both sides, and some people have a yellow crust at the corners.
Cause: saliva pools at the corners until the skin becomes soggy, and then Candida yeast or Staphylococcus bacteria get in. It is common in older adults with loose dentures, people with deep creases at the corners of the mouth, people with braces, people with diabetes, people using steroid inhalers, and people lacking iron, vitamin B2, B12 or folate.
Severity/urgency: not dangerous, it is not herpes, and it is not spread by kissing the way herpes is. But it will keep coming back if the underlying cause is not fixed.
When to see a doctor: if it has not healed after 2 weeks of treatment, if it recurs several times a year, if the tongue is smooth and red or you are pale and tire easily (possible anemia), or if there are white patches in the mouth too.
More detail on telling it apart from herpes is in Angular cheilitis: what causes it.
Canker sores on the inside of the lip (aphthous ulcer)
Image: Noorus · CC BY-SA 3.0 · edited
Appearance: shallow round or oval sores 2–10 millimetres wide with a white or yellow base and a clearly red edge, more painful than they look. They sit on the lining inside the lip, the inner cheek or under the tongue, not on the outer skin of the lip, and no blisters come first. Small sores heal in 7–14 days; large sores over 1 centimetre can take 2–6 weeks.
Cause: not fully known. Common triggers are biting the lip or brushing too hard, stress, lack of sleep, the days before menstruation, toothpaste containing the detergent sodium lauryl sulfate, and a lack of iron, vitamin B12 or folate.
Severity/urgency: not dangerous and not contagious, but if they recur very often together with genital sores, eye inflammation or chronic diarrhea, a systemic disease needs to be looked for.
When to see a doctor: a single sore that has not healed in 3 weeks, a sore larger than 1 centimetre, sores that follow one after another with no healing gap, or fever and weight loss.
Topical medicines and how to apply them to the sore are explained in Medicine for mouth sores: which one to use and how many times a day.
Cracked lips from isotretinoin acne medicine
Appearance: the lips become dry, peeling and cracked all over, starting within 1–2 weeks of beginning the medicine. Some people have cracked, bleeding corners of the mouth. Dry lips are a side effect seen in almost everyone who takes the drug.
Cause: isotretinoin reduces oil gland activity throughout the body. The lips, which have a thin skin layer, dry out before other areas, and symptoms increase with the dose.
Severity/urgency: not dangerous, and it improves on its own within a few weeks after stopping the drug. Most people do not need to stop the medicine because of dry lips.
When to see a doctor: if the lips crack so badly you cannot eat, if there are yellow crusts or pus at the lip border, or if there is a lot of peeling rash elsewhere. Tell the doctor who prescribed the medicine so the dose can be considered for adjustment.
Other side effects of this medicine and the monitoring are in the Isotretinoin guide.
Allergy to lipstick, lip balm or toothpaste (contact cheilitis)
Appearance: the whole lip is red, dry, peeling, itchy or stinging, sometimes slightly swollen. The rash can spread beyond the lip border. It usually appears within 1–3 days after changing lipstick, lip balm, toothpaste or mouthwash, but some people become allergic to something they have used for many years.
Cause: it can be irritation or allergy. Common substances include fragrance and mint or cinnamon flavours, preservatives, lipstick dyes, propolis wax, sunscreen ingredients in lip balm, and nickel from holding pens or metal clips in the mouth.
Severity/urgency: not dangerous, but it comes back every time you use the same substance. Applying more lip balm to treat dry lips may make it worse if that lip balm is the cause.
When to see a doctor: if there is no improvement 2–3 weeks after stopping the suspected product, if it recurs with no known cause, in which case the doctor may do a skin allergy patch test, or if the lip swells together with difficulty breathing, which needs the emergency room.
How contact allergy rashes work and how to find the culprit are in Allergic contact dermatitis, and sudden lip swelling is covered in Swollen lips: which kinds are dangerous.
Lip biting sores, injuries and mucus cysts
Image: Dozenist · CC BY-SA 3.0 · edited
Appearance: a bite or knock causes an irregular sore at the spot the teeth hit; it is painful and heals in 7–10 days. A mucus cyst (mucocele) is a soft, raised, clear or bluish bump 2–10 millimetres wide on the inside of the lower lip. It is painless, can burst and flatten, then grow back.
Cause: accidentally biting the lip, a habit of sucking or nibbling the lip, braces or chipped teeth that scrape the lining, and very hot food. A mucus cyst happens when a small salivary gland duct in the lip is torn so saliva leaks and collects under the lining.
Severity/urgency: not dangerous. Bite sores heal on their own once the biting stops, and about half of mucus cysts disappear on their own within a few weeks.
When to see a doctor or dentist: if there is a sharp tooth or appliance in the mouth that keeps scraping, if the sore has not healed in 2–3 weeks, or if a mucus cyst stays for more than 1–2 months and is bothersome. It is treated with minor surgery to remove the cyst together with the related salivary gland.
Chronic lip inflammation from sun (actinic cheilitis)
Appearance: the lower lip is constantly dry, peeling and rough with no period of full healing. The border between the lip and the facial skin becomes blurred, and there may be white patches, grey or brown spots, and crusts that fall off and return in the same place. It usually occurs in people over 40 who work outdoors.
Cause: years of accumulated ultraviolet light damage the skin cells of the lower lip, which gets more direct sun than the upper lip. Smoking adds to the risk.
Severity/urgency: it is a precancerous condition. Some cases turn into squamous cell skin cancer of the lip, so it should not be left alone even if it does not hurt.
When to see a doctor: see a dermatologist if the lower lip has been dry and peeling for more than 1–2 months, and be examined promptly if there is a thick hard spot, an open sore, or easy bleeding. The doctor may take a biopsy before choosing treatment.
Sun-related precancerous skin changes in other areas are explained in Sun-damage scaly patches (actinic keratosis).
A lip sore that has not healed in over 3 weeks (cancer must be ruled out)
Appearance: a sore or lump on the lip, mostly the lower lip, that has lasted over 3 weeks, with a raised thick or hard edge, a crust that falls off and then bleeds again and again, usually not very painful. Some people have enlarged lymph nodes under the chin that can be felt.
Cause: what must be ruled out first is squamous cell carcinoma of the lip, which is linked to sun and smoking. Less common causes include early syphilis sore (a single, firm-edged, painless sore), tuberculosis or deep fungal infection, and sores from immune diseases.
Severity/urgency: it needs to be examined within 1–2 weeks and should not be left to wait. Lip cancer found at an early stage responds well to surgery.
When to see a doctor: every lip sore that has not healed in over 3 weeks, even if painless. The doctor will take a small biopsy and send it for pathology to confirm.
Signs of this cancer in other areas are in Squamous cell carcinoma of the skin.
Lip sores with fever, rash elsewhere or red eyes
Some lip sores are only one part of a whole-body illness, which requires looking at more than the mouth.
Appearance: a lip sore with fever, together with one of the following: bumps or red spots on the palms and soles, several sores in the mouth with swollen red gums, honey-yellow crusts around the mouth and nose, or thick dark bloody crusts on the lips with red eyes and rings-within-rings rash resembling an archery target on the body.
Cause: in young children the common causes are hand, foot and mouth disease and a first herpes infection in the mouth (primary herpetic gingivostomatitis), which causes high fever and a mouth full of sores. Honey-yellow crusts are usually impetigo. Bloody lip crusts with red eyes and a target-like rash call for consideration of a severe allergic reaction such as erythema multiforme or Stevens-Johnson syndrome, which is often caused by drugs or infection.
Severity/urgency: a child whose mouth hurts so much they refuse to drink is at risk of dehydration within 1–2 days. Peeling or blistering skin together with sores in the mouth and eyes within 4–28 days after starting a new medicine is an emergency.
When to see a doctor: go to the hospital immediately if there are lip sores together with painful red eyes, blistering or peeling skin, or if a new medicine was just started. Take a child to the doctor if they urinate less, are drowsy, or have fever beyond 3 days.
Quick comparison of each type of lip sore
Cold sore: tingling comes first 6–24 hours earlier, then clustered clear blisters at the lip border, then a crust, healing in 7–10 days. Contagious.
Dry cracked lips: the whole lip is dry and tight with many cracks and no blisters. Improves in 3–7 days when you stop licking.
Lip-licking rash: a red peeling ring around the mouth as wide as the tongue reaches.
Angular cheilitis: cracked, soggy sores or a white coating at the corners of the mouth only.
Canker sore: a round white-yellow sore with a red edge inside the mouth, very painful, heals in 7–14 days, not contagious.
Allergy: red, peeling, itchy lips all over, linked to a newly used product.
Sun damage of the lip: lower lip peeling for months, blurred lip border.
Sore that needs a biopsy: lasts over 3 weeks, hard, bleeds easily.
Taking care of yourself when you have a lip sore
Whatever the cause, the following care helps the sore heal faster and keeps it from getting worse.
Stop licking, biting and picking at crusts. The crust is the body's natural cover for the sore. Picking it delays healing by several days and raises the chance of infection.
Apply a thin layer of petroleum jelly (petrolatum) 4–6 times a day and before bed for dry cracked lips, peeling lips and bite sores. Choose one with no scent, no colour, and no menthol, camphor or phenol, which feel cooling but irritate cracked skin.
Use a lip sunscreen of SPF 30 or higher when outdoors and reapply every 2 hours. It both reduces cold sore flare-ups and protects against sun damage of the lip.
Switch to a toothpaste without sodium lauryl sulfate if you often get canker sores or suspect a toothpaste allergy, and set aside any lip product you recently started for 2–3 weeks.
Avoid very spicy, very sour, very salty and very hot food until the sore closes. Use a straw for drinks when the sore is at the corner of the mouth.
Drink enough water and use a humidifier in air-conditioned rooms if you wake up with dry lips every morning, which often means you breathe through your mouth in your sleep.
If you suspect a cold sore, do not touch it and then touch your eyes. Wash your hands after applying medicine, and do not share handkerchiefs, cups or lip products with others until the crust falls off.
Medicines doctors use for lip sores, by cause
No single medicine works for every kind of lip sore, so choosing a medicine depends on the diagnosis. Below are the approaches dermatologists commonly use. The choice of medicine and dose for each person is up to the examining doctor.
Cold sores on the lip: medicine works best when started at the tingling stage, before blisters appear or within the first 24 hours.
Acyclovir 5% cream, applied 5 times a day (every 3–4 hours while awake) for 4–5 days, shortens the episode by about 0.5–1 day.
Valacyclovir by mouth, 2 grams twice, 12 hours apart, for 1 day, for adults who can tell an outbreak is coming. It works better than the cream, and the dose must be adjusted in people with reduced kidney function.
For people with more than 6 outbreaks a year, a doctor may prescribe a low daily dose of an oral antiviral to prevent recurrences, for example valacyclovir 500 milligrams once a day, then reassess every 6–12 months.
Do not apply a steroid cream to a cold sore, because it can make the virus spread and slow healing.
Dry cracked lips and peeling lips: petroleum jelly 4–6 times a day is the main treatment. If there is a lot of red, itchy inflammation, a doctor may prescribe hydrocortisone 1% ointment once or twice a day for no more than 5–7 days, then go back to a barrier alone. A crack in the middle of the lip that recurs every year sometimes needs minor surgical correction.
Angular cheilitis: antifungal medicine is the main treatment, along with fixing the underlying cause.
Antifungal miconazole 2% cream or clotrimazole 1% cream, applied twice a day for 1–2 weeks.
If it is very inflamed, a doctor may use the antifungal together with hydrocortisone 1% for a short 5–7 days.
If there is a yellow crust from bacteria, use mupirocin 2% or fusidic acid 2% three times a day for 5–7 days.
Fix the underlying cause too, such as adjusting or cleaning dentures, applying petroleum jelly at the corners before bed, and checking blood for iron, vitamin B12 and blood sugar if it recurs.
Canker sores inside the lip: medicine applied inside the mouth is the main treatment.
Triamcinolone acetonide 0.1% oral paste, dabbed on thinly 2–4 times a day after meals and before bed until the sore heals, usually about 5–7 days.
Chlorhexidine 0.12% mouthwash, swished for 30 seconds twice a day, helps reduce repeat infection.
For people with large sores or sores that keep coming one after another, a doctor may order blood tests and consider oral medicine case by case.
Allergy to lipstick or toothpaste: stop all suspected products and use petroleum jelly alone. If it is very inflamed, use hydrocortisone 1% for no more than 7 days. For people with recurrences, a doctor may use tacrolimus 0.03–0.1% ointment, which does not thin the skin, and send you for a skin patch test to find the substances to avoid permanently.
Sun damage of the lip: lip sunscreen every day is the foundation. Treatment of the abnormal area depends on the findings, for example 5-fluorouracil 5% or imiquimod 5% applied under a doctor's supervision, cryotherapy (freezing), or surgery to remove the abnormal lip skin. Any thickened, hard spot must always be biopsied first.
Bacterial infected sores (honey-yellow crusts): mupirocin 2% three times a day for 5 days. If it has spread to several spots or there is fever, the doctor will consider an oral antibiotic.
Choose medicine by the active ingredient name on the label, not the brand, and do not apply a multi-ingredient cream without knowing what kind of sore you have.
Lip sores in children: how they differ from adults
The common causes in children are not the same as in adults.
A child aged 1–5 with a high fever, swollen red gums and several sores in the mouth and on the lips: this is usually a first herpes infection. A doctor may give an oral antiviral if it can be started within the first 3–4 days of symptoms. The most important thing is to keep the child drinking enough fluids.
A young child with mouth sores plus red spots or bumps on the hands, feet or bottom: this is usually hand, foot and mouth disease, which clears on its own in 7–10 days. Stay home from school as advised.
A school-age child with a red peeling ring around the mouth in winter: this is usually lip-licking rash. Treat it by applying a thick layer of petroleum jelly several times a day so the child does not need to lick.
Honey-yellow crusts around the mouth and nose: this is usually impetigo, which spreads easily among children.
Children should not be given numbing medicine for the mouth on your own without consulting a doctor, and should see a doctor right away if they refuse to drink, urinate less, or become drowsy.
What not to do when you have a lip sore
Do not pick at crusts or peel lip skin that has not come off yet.
Do not apply a steroid cream to blisters or to a sore that might be a cold sore.
Do not put toothpaste, alcohol, lemon juice or salt on a sore, which irritates and deepens it.
Do not repeatedly apply fruit-flavoured, menthol or camphor lip balm when your lips are cracked.
Do not keep using a cream bought on hearsay for more than 2 weeks if it is not improving.
Do not leave a sore that has not healed in over 3 weeks alone because you think no pain means no danger.
When to see a doctor and what the doctor will check
See a dermatologist if any one of the following applies.
A lip sore that has not healed in over 3 weeks, or feels hard, raised and thick, or bleeds easily.
A lower lip that has been dry and peeling for more than 1–2 months in someone who is regularly in the sun.
Cold sores that flare up more than 6 times a year, or a sore that spreads widely.
Angular cheilitis or canker sores that keep recurring with no healing gap.
Fever, swollen lymph nodes in the neck, or a sore with a rash elsewhere.
Go to the emergency room immediately for lip swelling together with difficulty breathing, or for a mouth sore together with red eyes and blistering or peeling skin (call 1669 in Thailand).
At a dermatology visit, the doctor looks at the location and appearance of the sore and asks about lipstick, toothpaste, medicines, outdoor work and smoking. Most cases can be diagnosed by examination. If it is unclear whether it is a cold sore, the sore may be swabbed for testing; if a fungal infection at the corners is suspected, skin may be scraped and viewed under the microscope; if an allergy is suspected, a skin patch test is done; and if the sore is chronic or hard, a small biopsy is taken for examination.
Quick summary
Check the location first: clustered blisters at the lip border are usually a cold sore, the corners of the mouth are usually angular cheilitis, the inside of the mouth is usually a canker sore, and a dry cracked whole lip is usually dry lips or an allergy.
For cold sores, use an antiviral from the tingling stage, for example acyclovir 5% five times a day for 4–5 days, and do not apply a steroid to a cold sore.
Dry cracked lips improve in 3–7 days by stopping lip licking and applying petroleum jelly 4–6 times a day.
For angular cheilitis use an antifungal for 1–2 weeks; for canker sores use triamcinolone 0.1% oral paste 2–4 times a day.
A lip sunscreen of SPF 30 or higher helps reduce cold sore flare-ups and protects against sun damage of the lip.
A lip sore that has not healed in over 3 weeks, or is hard or bleeds easily, must be examined by a doctor and may need a biopsy.
Frequently asked questions about lip sores
What causes a sore on the lip?
The most common cause is dry cracked lips from cold air or lip licking. Others are cold sores, which are clustered clear blisters at the lip border, angular cheilitis at the corners of the mouth, canker sores on the inside of the lip, and allergy to lipstick or toothpaste. Less common but important causes are chronic sun damage of the lip and skin cancer of the lip, which usually appears as a lower lip sore lasting more than 3 weeks. Looking at where the sore is, whether blisters came first, and how long it has lasted helps tell the causes apart a great deal.
I have a sore on my lip, how do I make it heal?
Start by stopping licking, biting and picking at crusts. Apply unscented petroleum jelly 4–6 times a day, avoid very spicy or sour food, and stop any lipstick or lip balm you just started. Then use medicine that matches the cause: an antiviral for cold sores, an antifungal for angular cheilitis, an oral steroid paste for canker sores. If there is no improvement after 2 weeks of care, or the sore has lasted over 3 weeks, have a doctor check exactly what it is.
What should I put on a lip sore?
It depends on the type of sore. Dry cracked lips or bite sores use petroleum jelly. Cold sores use acyclovir 5% cream 5 times a day for 4–5 days, started as soon as you feel tingling. Angular cheilitis uses miconazole 2% or clotrimazole 1% cream twice a day for 1–2 weeks. Canker sores inside the mouth use triamcinolone 0.1% oral paste 2–4 times a day. Sores with yellow crusts use mupirocin 2%. Do not apply a steroid cream to a sore that may be a cold sore.
How many days does a lip sore take to heal?
Cold sores heal in 7–10 days, small canker sores in 7–14 days, and dry cracked lips improve in 3–7 days once you stop licking and apply a barrier regularly. Angular cheilitis improves in 1–2 weeks with an antifungal, and bite sores heal in 7–10 days. A sore that has not healed within 3 weeks is not normal for these conditions, and you should see a doctor to look for other causes, including a biopsy if the sore is hard or bleeds easily.
What causes a dry lip border with sores?
A dry, cracked and sore lip border is most often caused by repeated lip licking in dry weather, which creates a red peeling ring around the mouth. Next come allergy to lip balm, lipstick or toothpaste, and side effects of isotretinoin acne medicine. Clustered clear blisters that burst are probably a cold sore. A chronic lower lip problem in someone with a lot of sun exposure, with a blurred lip border, should be checked by a dermatologist to rule out actinic cheilitis.
The corners of my mouth peel with a white coating, what should I do?
A white coating at the corners of the mouth with cracked, soggy skin is usually angular cheilitis with Candida yeast. Apply miconazole 2% or clotrimazole 1% cream twice a day for 1–2 weeks, apply petroleum jelly at the corners before bed to keep saliva from pooling, and clean dentures every night. If it recurs often, have blood tests for iron or vitamin B12 deficiency and for diabetes. If the white coating is on the lower lip itself and cannot be scraped off, have it examined by a doctor.
Related reading: Cold sores · Dry peeling lips and cracked lips · Angular cheilitis · Medicine for mouth sores · Swollen lips · Dark lips · For other skin conditions, see the skin condition article index
This article gives general medical information and does not replace diagnosis by a doctor. The choice of medicine and dose is up to the examining doctor.
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed November 10, 2026
Image: WizardOfOz · CC BY-SA 4.0 · edited
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