Warts: Causes, the 5 Types, Foot Warts vs Corns, and How to Treat Them Without Letting Them Spread
Warts (verruca) are rough, raised bumps on the skin caused by infection of the upper skin layer with the human papillomavirus (HPV), which makes skin cells multiply and thicken into a bump. Common skin warts are not cancer and are usually harmless, but they are contagious, can spread to new spots on your own body, and in children about 2 in 3 clear on their own within 2 years.
Warts affect about 7–12% of the general population and 10–20% of school-age children. The questions patients ask dermatologists most often are few: what causes warts, are they dangerous if left alone, do they go away on their own, which medicine to apply, and which type of freezing or burning is best. This article answers each one, organised by where the wart grows, because warts on the hands, feet, face and genitals are not treated the same way. It also gives the actual drug names, strengths and treatment times.
What causes warts
The cause of warts is the HPV virus, which has more than 200 types, each preferring a different site. Warts on the hands and fingers are usually caused by types 2, 4, 27 and 57. Warts on the soles are usually type 1. Flat warts on the face are types 3 and 10, and genital warts are mainly types 6 and 11.
The virus enters through scrapes, cracks or tiny scratches that are almost invisible, then settles in the upper skin cells. Skin that stays wet until it turns soft and macerated, such as feet soaked in a swimming pool or hands washing dishes all day, is infected more easily than dry skin.
One point worth knowing: skin warts are caused by a virus. They are not caused by dirtiness, certain foods, or touching a toad as folklore says, and they are not inherited, although each person's immunity makes some people develop them more easily and clear them more slowly than others.
How do warts spread
Warts spread in 3 ways, the same explanation that medical textbooks use.
Direct contact with another person's wart, especially when our own skin has a small break.
Indirect contact through shared items such as towels, shoes, socks, nail clippers, foot files, and wet floors in shared showers, swimming pools and locker rooms, which is the main route for warts on the soles.
Spread on your own body (autoinoculation) Picking, biting, scratching or shaving over a wart carries the virus to new spots, sometimes growing in a line along the scratch.
The risk of catching a wart from a single contact is not high, and many people in the same household never get infected, but repeated daily sharing of items increases the chance over time.
How long until warts appear (incubation period)
After exposure, most warts take 2–6 months to appear as a visible bump, and some take almost a year. This is why patients often cannot think where they caught it, and why new bumps may appear a few months after the original ones have been treated and cleared, because the virus already in the surrounding skin had not yet shown itself at the first treatment.
Who gets warts easily and who has trouble clearing them
Children aged about 5–16, the age group in which warts are most common.
People whose hands or feet are often wet, such as swimmers, kitchen workers, and people working in meat and seafood processing.
People who bite their nails, pick the skin around the nails, or often have dry, cracked skin.
People with weak immunity, such as those taking immunosuppressive drugs after an organ transplant, patients with autoimmune disease on immunosuppressants, and people living with HIV. This group often has many warts that resist treatment and need close follow-up with a doctor.
People with diabetes who have warts on the feet. They are not more likely to get warts than other people, but they have a high risk of wounds if they treat the warts themselves with a corrosive medicine, so they should not self-treat.
Warts on the hands and fingers (common warts)
Appearance: Hard raised bumps with a rough, cauliflower-like surface, 1–10 mm, skin-coloured or grey-brown, usually on the backs of the hands, fingers and knuckles, and on the elbows and knees in children. If the top layer is pared off you can see tiny black dots, which are clotted capillaries. The medical name is common wart or verruca vulgaris.
Cause: HPV types 2, 4, 27 and 57, spread through scrapes on the hands or by biting and picking.
Severity/urgency: Not dangerous and not an emergency. A topical medicine can be tried first in healthy adults. If there are many bumps, start treatment early, because the more there are, the harder they are to clear.
When to see a doctor: The bump has not shrunk after 12 weeks of continuous treatment, there are more than 5–10 bumps, it is spreading quickly, it is on a finger and interferes with use, or it does not look like an ordinary wart.
Warts around and under the nails
Appearance: Rough bumps at the nail edge or in the skin around the nail, or growing under the nail plate so that the nail lifts or becomes misshapen. Some people have pain when pressing or picking things up. This is called a periungual wart.
Cause: Common in people who bite their nails or pick the skin around them, because this opens a wound for the virus to enter and carries it from one finger to another.
Severity/urgency: The hardest to treat of the hand warts, slow to clear, and burning too hard can damage the nail root so that the nail grows back misshapen permanently.
When to see a doctor: A doctor should assess it from the start, especially in adults with a single long-standing bump around or under the nail, because early squamous cell carcinoma in situ near the nail can look very much like a wart.
Warts on the soles and heels
Appearance: Flat, hard bumps pressed into the skin by body weight, with thick skin on top like a corn, small black dots scattered inside, and the skin lines interrupted at the bump. They hurt when walking. Some people have many small bumps grouped into a patch, called a mosaic wart. The medical name is plantar wart or verruca plantaris.
Cause: HPV types 1, 2 and 4, caught from wet floors in public places through sole skin softened by water.
Severity/urgency: Not dangerous, but they interfere with walking and exercise. A mosaic wart covering a wide area can take several months to treat. Warts should not be cut out or burned deeply on weight-bearing spots, because a scar on the sole may hurt for life.
When to see a doctor: You cannot tell whether it is a wart or a corn, you have diabetes or numb feet, the pain is bad enough to change your walking, or there is a lump on the sole that is dark in colour, growing, or an ulcer that will not heal, because some melanomas on the sole have no pigment and have been treated as warts for years.
Foot warts vs corns: what is the difference
Both are hard bumps on the sole that hurt when walking, but a wart is caused by a virus and is therefore contagious, while a corn is caused by repeated pressure and friction and is not an infection. There are 4 basic ways to tell them apart.
Black dots in the centre: Present in warts (clotted capillaries), absent in corns, which have a clear yellow core in the middle instead.
Skin lines: A wart interrupts the lines on the sole at the bump, whereas with a corn the lines still run across it continuously.
Type of pain: A wart hurts when squeezed from the sides, a corn hurts when pressed straight down.
Location: A corn sits over a bony prominence or pressure point, while a wart can appear anywhere and is often multiple.
If you still cannot tell, a dermatologist can confirm with a dermatoscope within a few minutes. Telling them apart correctly matters, because putting a corn plaster on a wart, or paring a wart down yourself as you would a corn, often makes the virus spread more. Read more in our article What causes corns on the feet, and how are they different from foot warts
Warts on the face: flat warts and filiform warts
Warts on the face come in two main forms that look very different.
Appearance: The first is the flat wart (verruca plana), smooth flat bumps 1–4 mm, skin-coloured or light brown, growing in groups of dozens on the forehead, cheeks, chin, backs of the hands and shins, often in a line along a scratch or shaving mark. The second is the filiform wart, a long thin projection with small fronds at the tip, usually on the eyelids, lips, nose and chin.
Cause: Flat warts are caused by HPV types 3 and 10 and spread through shaving the beard or legs, or scratching. Filiform warts are caused by the same types as common warts.
Severity/urgency: Not dangerous, but they affect confidence, and facial skin develops dark marks or pale patches after treatment more easily than elsewhere, so never put the strong wart-removing medicines sold for hands and feet on the face.
When to see a doctor: See a doctor every time a wart appears on the face, because a method that leaves no mark must be chosen, and in adults a facial bump thought to be a wart may be a seborrheic keratosis, a skin tag or certain skin cancers.
Bumps on the neck, underarms and eyelids that are soft, have a stalk and are not rough are usually skin tags, which are not caused by HPV the way ordinary warts are. Read how to tell them apart in What causes skin tags, and how to tell them from warts and moles
Genital warts
Appearance: Soft skin-coloured or pink bumps with a frond-like surface resembling a cockscomb or cauliflower, on the genitals, groin and around the anus. The medical name is condyloma acuminata.
Cause: HPV types 6 and 11, about 90%, spread mainly through sexual contact.
Severity/urgency: The warts themselves come from low-risk types, but a person infected with these types may also carry high-risk types such as 16 and 18, which are linked to cervical, anal and penile cancer, so they must be managed differently from warts on the hands and feet.
When to see a doctor: Every time. Do not apply wart-removing medicines bought for the hands and feet to the genitals, because they burn the mucous membrane into deep wounds. Partners should be examined, and women should keep their cervical cancer screening appointments. Read more in What causes genital warts, and how to tell them from skin tags and pearly penile papules
Molluscum contagiosum is not an HPV wart
Despite having wart in its name, molluscum contagiosum is caused by a different family of virus, a poxvirus. The bumps are round, smooth and shiny, 2–5 mm, with a small dimple in the centre. It is most common in young children and mostly clears on its own within 6–18 months. Its care differs from HPV warts, so wart-removing medicines should not be used on molluscum. Read more in Molluscum contagiosum in children: treat or wait for it to clear
Are warts dangerous if left alone, and which warts are cancer
Warts on the hands, feet and face are caused by low-risk HPV types and almost never turn into cancer, so leaving them does not make them malignant. The harm of leaving them is three-fold: they spread and multiply until they are harder to treat, they pass to people at home, and they hurt in use, especially warts on the soles and around the nails.
What is truly dangerous is a bump that is not a wart but looks like one, including squamous cell carcinoma, amelanotic melanoma and verrucous carcinoma. You should see a doctor for examination, and a biopsy may be taken, if there are any of the following features.
A single bump that grows fast or keeps getting bigger in an adult over 40–50.
Bleeds easily, ulcerates, or forms a chronic crater lasting more than 4–6 weeks.
Dark, black or multi-coloured within a single bump.
Treated as a wart for 3–6 months with no response at all, or keeps returning to the same spot.
A long-standing bump around or under the nail in an adult.
Many warts in someone with weak immunity, because this group has a skin squamous cell carcinoma risk several times higher than the general population.
A dermatologist's principle is to get the diagnosis right first, then treat. Burning off a bump that is actually cancer without sending it for testing can mean missing the treatment you should have had at an early stage.
Do warts go away on their own
Yes. A wart is an infection that the body's immunity eventually clears. Follow-up data in school-age children show that about half clear on their own within 1 year and about 2 in 3 within 2 years. In adults they clear more slowly and some last for years.
A sign that a wart is about to clear is that the whole bump turns dark black within a few days because the blood vessels feeding it clot, after which it dries and falls off within 1–3 weeks without leaving a scar.
For this reason, in a child whose wart does not hurt, does not interfere and is not spreading fast, watching without treatment is a medically correct option, not neglect. In adults, warts that hurt, spread or are multiple should be treated while there are still few.
How a doctor examines a wart (before choosing treatment)
Most warts are diagnosed by looking and by dermatoscopy, which shows small pinpoint bleeding spots or dotted capillaries inside the bump. No blood test is needed. The doctor may pare off the top of the skin thinly to look at the black dots and skin lines. In the following cases the doctor will take a small biopsy for pathology.
A bump that looks different from an ordinary wart, or has the warning signs listed above.
Warts in adults that have resisted several rounds of treatment.
An unclear bump in the genital area.
Preparing for your visit: Note how long you have had it, what medicines you have used, and for how many weeks. Tell the doctor about any medical conditions, medicines you take, and pregnancy. Do not apply wart-removing medicine or pick at the bump for 3–5 days before the visit, so the doctor can see its true appearance.
Which wart treatment is best: an overview of the options
No single method suits every wart, and no method guarantees it will not come back. The doctor chooses by type, site, size, number, age, pain tolerance, and what has already been tried. The general principles are as follows.
Recent warts on the hands and feet in adults: Start with salicylic acid, or freezing, or both together.
Thick warts or ones resistant to topical medicine: Repeated courses of freezing, or electrocautery with curettage.
Flat warts on the face: A vitamin A-type topical or an immune-stimulating topical, avoiding methods that leave marks.
Filiform warts on the face: Cut off at the base with small scissors or electrocautery, which is quick and leaves a small wound.
Warts resistant after several rounds: Injection into the bump, or immune-stimulating treatment.
Young children: Start with watching or a painless topical, and avoid painful freezing if it is not necessary.
Topical wart medicine: how to use salicylic acid and for how many weeks
Salicylic acid is one of the best-studied topical medicines for warts on the hands and feet. It works by gradually peeling away the layers of the wart and stimulating local immunity. Pooled studies found that about half of warts cleared, compared with about 1 in 4 in the placebo group.
Strength: For warts on the hands, 15–26% as a solution or gel is commonly used, and many formulas are combined with lactic acid. For warts on the soles, where the skin is very thick, a 40% plaster may be used as the doctor advises.
How to use: Soak the wart in warm water for 5–10 minutes and dry it. Gently rub away the dead white skin with a file or pumice stone kept only for the wart. Apply the medicine only on the wart. Put petroleum jelly around it to protect healthy skin from the medicine. Apply once a day at bedtime and cover with a plaster.
Duration: It must be used every day without a break for at least 12 weeks. Most people see the bump get smaller in 4–6 weeks. Keep using it until the skin there has normal skin lines again, not just until the bump flattens.
What makes it work or fail: Removing the dead skin before every application is the deciding factor. If you do not, the medicine does not reach the virus. Inconsistent use is the leading reason topical medicine fails.
Precautions: Stop temporarily if the surrounding skin is red, stinging or has a wound. Do not use on the face, genitals, moles or open wounds. People with diabetes, numb feet or poor circulation to the legs should not apply it to the feet themselves. Never share the file with anyone else.
Other topical medicines a doctor may prescribe in some cases include:
Tretinoin (vitamin A acid) 0.025–0.05% Apply thinly once a day at bedtime for flat warts on the face, for 4–8 weeks. It makes the skin peel and the flat warts come away with it. Do not use in pregnancy.
Imiquimod 5% cream, an immune stimulant Used mainly for genital warts. Apply 3 times a week at bedtime, wash off after 6–10 hours, for up to 16 weeks. A doctor may use it for flat warts on the face in some cases.
5-fluorouracil 5% cream Used for some resistant warts under a doctor's supervision. Do not use in pregnancy.
Each topical wart medicine must be chosen and prescribed by the doctor who examines you, based on the type and site of the wart.
Freezing warts with liquid nitrogen
Cryotherapy uses liquid nitrogen at about −196 degrees Celsius, sprayed or dabbed on the wart until the bump and about 1–2 mm of the surrounding rim turn white. The extreme cold destroys the infected cells and prompts the immune system to deal with the virus.
How many sessions: Most need repeat freezing every 2–3 weeks, 3–6 times in total. Effectiveness is similar to salicylic acid topical, and results are better when both are used together.
Does it hurt: A stinging sensation like an ice bite during freezing and a throbbing ache for about 1–2 hours afterwards. No local anaesthetic injection is needed for small warts.
Afterwards: Within 1–2 days it often swells into a blister or blood blister. Do not puncture it. Leave it to dry and fall off by itself within 7–14 days.
Side effects to know about: Dark marks or pale patches after freezing, which are common in darker skin and may last for months, new warts growing in a ring around the old freezing site (ring wart), and freezing too hard near the nail base, which can make the nail misshapen.
Limitations: Young children often cannot tolerate the pain, and freezing the side of a finger needs care because of the nerves.
Electrocautery and curettage for warts: how many days to heal
Electrocautery with curettage involves injecting local anaesthetic, then using heat from an electric current to destroy the wart tissue and scraping it out in a single session. It suits thick warts, filiform warts on the face, or warts resistant to topical medicine and freezing.
Advantages: Results in a single visit more often than the other methods, with no need to come back repeatedly.
How many days to heal: Wounds on the face usually heal in 7–10 days, on the hands in 10–14 days, and on the feet it may take 2–3 weeks. During this time the wound needs dressing and should not be soaked in water for long.
Does it hurt: It does not hurt during the procedure because of the anaesthetic. After it wears off the pain is like a graze, and you can take paracetamol for pain.
Disadvantages: A greater chance of scarring than freezing. Warts can return in about 20–30% because the virus in the surrounding skin is still there, and doctors usually avoid weight-bearing spots on the sole, because a scar there may hurt permanently.
Surgical removal and carbon dioxide laser
Surgical excision with stitches is generally not recommended for warts on the hands and feet, because it leaves a long scar and warts can grow back in the scar. The exceptions are filiform warts on the face and eyelids, which are easily snipped at the base with small scissors, leave a small wound and heal in 5–7 days, or a lump suspected of being cancer, which must be removed whole and sent for testing.
Carbon dioxide (CO2) laser uses light energy to vaporise the wart tissue layer by layer. It suits many warts, warts in sites where other methods are hard to use, or some genital warts. Local anaesthetic is needed, wounds heal in 2–4 weeks, and there is a risk of scarring and skin colour change, as with electrocautery. Results vary from person to person, and some people need more than one session.
Resistant warts that have not cleared after many rounds: what else can be done
For warts that have not responded to topical medicine and freezing for at least 3–6 months, a dermatologist has further options, considered case by case.
Bleomycin injection into the bump A low-dose cytotoxic drug injected only into the wart, used for resistant warts on the hands and feet. It hurts during the injection, and the wart turns dark before falling off in 2–4 weeks. Not for use in pregnancy, in children, or in people with poor circulation to the fingertips.
Antigen injection into the bump (intralesional immunotherapy) For example a Candida antigen, injected every 3–4 weeks for 3–5 sessions to prompt the immune system to recognise HPV. The advantage is that warts that were not injected may also clear.
Contact sensitising treatment (diphenylcyclopropenone or DPCP) Applied to the wart once a week in the clinic. It suits many warts or warts in children who cannot tolerate freezing.
Immune assessment In an adult with unusually many warts that resist every method, the doctor may recommend checking for weak immunity as well.
Why warts come back after treatment
HPV is still hiding in the normal skin around the bump, which was not treated, and it surfaces again 2–6 months later.
Stopping the topical medicine too early when the bump flattens, although the skin lines have not yet returned to normal.
Habits that spread the virus continue, such as biting, picking, or shaving over the area that was affected.
Reinfection from the same shoes, socks or file that are still in use.
Immunity is still unable to deal with the virus, which is most common in adults and in people taking immunosuppressants.
So doctors often schedule 1–2 follow-up visits after the warts clear and advise coming early when a new bump appears, because small bumps are much easier to treat.
Treating warts yourself: how far you can go and what not to do
A healthy adult with a few small warts on the hands or feet, who is sure they are warts, can start self-care with salicylic acid as described above. What you should not do includes the following.
Cutting, paring, digging out or tying off the wart yourself risks bleeding, bacterial infection, scarring and spreading the virus.
Using strong wart-removing medicine on the face, genitals, moles or bumps you are unsure about It burns delicate skin into wounds and permanent dark marks.
Burning with incense, fire, red lime, acid or corrosive herbs risks burns and raised scars.
Using over-the-counter freezing sprays They are much less cold than liquid nitrogen, and if used wrongly can give the surrounding skin a cold burn.
Applying raw garlic or vinegar There is not enough good evidence, and it often causes chemical burns of the skin.
Covering the wart with duct tape Study results conflict, and some found no difference from placebo, so it should not replace the main treatment.
The information in this article does not replace an examination by a doctor. If you have used a topical for the full 12 weeks without improvement, or are not sure it is a wart, have a dermatologist assess it.
Warts in children and in pregnancy
Warts in children: Most clear on their own. The aim is not to hurt the child more than necessary. If the wart is not bothersome, doctors usually advise watching, or a painless salicylic acid topical. Keep nails short, do not bite them, and wear sandals in public places. Genital warts in a child always need a doctor.
Warts in pregnancy: Warts often grow and multiply during pregnancy and often shrink after delivery. Freezing can be used safely, but tretinoin, 5-fluorouracil and bleomycin injection must not be used. Always tell the doctor that you are pregnant or planning a pregnancy.
Preventing warts from spreading and from passing to people at home
Cover the wart with a plaster, and wash your hands after touching the wart or after applying medicine.
Do not share towels, shoes, socks, nail clippers or files with anyone. Use a wart file separate from your ordinary foot file.
Wear sandals in shared showers, swimming pools, gyms and locker rooms.
Change socks every day, and dry your feet and between the toes. People with very sweaty feet should rotate their shoes.
Stop biting your nails and picking the skin around them.
If you have flat warts on the face, stop shaving that area for a while, or use an electric shaver instead of a razor.
HPV vaccine: The 9-valent vaccine protects against types 6 and 11, which cause about 90% of genital warts, and against the types linked to cervical cancer. It can be given from age 9, and children aged 9–14 need 2 doses. But the vaccine does not protect against warts on the hands and feet, and does not treat warts you already have.
When to see a dermatologist
You are not sure it is a wart, or cannot tell it from a corn, skin tag, seborrheic keratosis or mole.
The wart is on the face, genitals, around the anus, or around or under the nails.
You have used a topical continuously for 12 weeks without improvement.
The warts are spreading fast or there are more than 5–10 bumps.
There is bleeding, ulceration, colour change or fast growth.
You have diabetes, numb feet, circulation problems or weak immunity.
A wart on the sole hurts enough that you cannot walk normally.
See other common skin conditions and how to tell them apart at Common skin conditions.
In brief
Warts are caused by the HPV virus entering through tiny scrapes. They spread in 3 ways: direct contact, shared items, and spread on your own body from picking and scratching.
After exposure, most take 2–6 months for the bump to appear.
Warts on the hands, feet and face almost never become cancer, but a bump that grows fast, bleeds, is dark in colour or resists treatment may not be a wart and needs a doctor's examination.
In children about half clear on their own in 1 year and about 2 in 3 in 2 years.
Salicylic acid 15–26% needs the skin rubbed down before each application and must be used continuously for at least 12 weeks, while freezing is done every 2–3 weeks, 3–6 times.
For warts on the face and genitals, do not use wart-removing medicine yourself. Let the doctor choose a method that leaves no mark.
Frequently asked questions about warts
Are warts dangerous if left alone
Warts on the hands, feet and face are caused by low-risk HPV types, and leaving them almost never makes them turn into cancer. But they gradually spread and multiply, can pass to people at home, and the more there are, the harder they are to treat. Genital warts should always be seen by a doctor, because high-risk HPV types may be present as well. A bump that grows fast, bleeds, ulcerates, is dark in colour, or does not improve when treated as a wart may not be a wart, and a dermatologist should examine it and may take a biopsy.
Which wart treatment is best
No single method suits everyone. For warts on the hands and feet in adults, the usual start is salicylic acid every day for at least 12 weeks, or freezing with liquid nitrogen every 2–3 weeks, which work about equally well and work better together. Thick or resistant warts use electrocautery with curettage, flat warts on the face use a vitamin A-type topical, and warts resistant after many rounds may use injection into the bump or immune-stimulating treatment. The doctor chooses by the type, site, number and age of the patient.
Which warts are cancer
Ordinary HPV warts on the skin almost never turn into cancer. What to watch for is skin cancer that looks like a wart. Signs to see a doctor include a single bump that grows fast in an adult, easy bleeding or an ulcer lasting more than 4–6 weeks, dark or multi-coloured bumps, a long-standing bump around or under the nail, a lump on the sole treated as a wart for a long time without clearing, and many warts in people with weak immunity. HPV types 16 and 18 in the genital area are linked to cervical and anal cancer.
How long until warts appear
After HPV exposure, most warts take about 2–6 months to appear as a visible bump, and some take almost a year, so people often cannot think where they caught it. It is also why new bumps can appear within a few months after the original ones are treated, because the virus embedded in the surrounding skin had not yet shown itself at the first treatment. Follow-up after the warts clear, and treating new bumps while they are small, helps keep them under control.
What medicine do you apply to warts
The main topical for warts on the hands and feet is salicylic acid at about 15–26%, applied once a day at bedtime after soaking in warm water for 5–10 minutes and rubbing away the dead skin, used continuously for at least 12 weeks. For flat warts on the face a doctor may prescribe tretinoin 0.025–0.05%. Genital warts use different medicines, such as imiquimod 5%, which a doctor must prescribe. Do not use wart-removing medicine on the face, genitals, moles, or in people with diabetes who have numb feet.
Do warts go away on their own
Yes. A wart is an infection that immunity eventually clears. In school-age children about half clear on their own within 1 year and about 2 in 3 within 2 years. In adults they clear more slowly. A sign that a wart is about to clear is that the whole bump turns dark black within a few days, then dries and falls off within 1–3 weeks without leaving a scar. In a child whose wart is not bothersome, watching is therefore a reasonable choice, but if the wart hurts, spreads fast or is on the face, see a doctor.
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed October 2, 2026
The information in this article is for basic understanding only and does not replace diagnosis and treatment by a doctor. The choice of medicine, its strength and the method of freezing or burning must be decided by the doctor who examines you.
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