Warts: The Complete Guide to Types, Causes, and Treatment

You found a rough, raised bump on your finger, your foot, or the back of your hand. It is firm. It might have tiny dark dots in it. It was not there a few months ago, and now it is, and maybe a second one has appeared nearby. Most likely, this is a wart.

You have probably also read that a wart has a root or a core you have to dig out, and that until you get it, the wart keeps coming back. That is the part almost everyone gets wrong, and it is the reason so many people injure their own skin trying. Warts are one of the most common skin growths in the world. They are caused by a virus, they are usually harmless, and most of them can be treated. This guide walks through what warts are, what is actually inside one, the subtypes that look and behave differently, why they show up, whether the removal pens people keep asking about really work, and the few situations that genuinely need a doctor.

What are warts?

A wart is a small, rough growth caused by an infection of the top layer of skin with the human papillomavirus (HPV). The virus tells skin cells to multiply faster than normal, and the result is a thickened, raised bump. According to NIH MedlinePlus, warts are common and usually harmless, and many eventually go away on their own, though that can take months or years.

A typical wart is firm to the touch, rough or grainy on the surface, and the same color as your skin or slightly darker. Many warts have tiny black dots inside them. Those dots are small clotted blood vessels, not seeds, despite the common nickname. The dots are one of the most reliable signs that a bump is a wart and not something else.

What warts look like

Warts vary by where they grow and which strain of HPV caused them. Some are dome-shaped and raised, some are flat and barely textured, and some are long and thread-like. They can appear alone or in clusters. They do not usually hurt, with one important exception: a wart on the sole of the foot can be pressed flat by your body weight and become painful to stand on.

Types of warts

Knowing the subtype matters, because the subtype drives which treatment fits. Here are the common ones.

Common warts

Common warts are the dome-shaped, rough bumps most people picture. They grow most often on the hands, fingers, and around the nails, and they have the classic grainy surface with black dots. They are the most frequently treated subtype at home.

Plantar warts

Plantar warts grow on the soles of the feet. Because you walk on them, they get pushed inward and flat, and they can develop a hard, callused ring around a central plug of thickened skin. They are often the most stubborn and the most uncomfortable subtype. For a detailed subtype breakdown, see our guide on plantar vs common vs flat warts.

Flat warts

Flat warts are smaller, smoother, and flatter than common warts. They tend to appear in large numbers, often on the face, the backs of the hands, or the legs. Because they are subtle, people often have dozens before noticing.

Filiform warts

Filiform warts are long, narrow, finger-like projections. They show up around the mouth, nose, and eyes, and they grow quickly. Their thread-like shape makes them easy to identify and, because they sit on a narrow stalk, often well suited to precise at-home treatment.

Periungual warts

Periungual warts grow around and under the fingernails and toenails. They can be painful, can distort nail growth, and are harder to reach, which makes them one of the trickier subtypes to treat at home.

What is inside a wart: the anatomy, and the so called core

A wart has no root and no living core you can pull out. That single fact changes how you should treat one. What sits inside a wart is thickened skin, a cluster of virus-infected skin cells, and a bundle of small blood vessels feeding the growth from below. Nothing anchors it into the deeper tissue, so there is nothing to dig for.

Do warts have cores?

No, not in the way the word suggests. Warts do not have a seed, a root, or a solid centre that can be extracted whole. The idea comes from plantar warts, which do form a dense central plug, but that plug is hardened keratin, the same protein as a callus, and it is part of your own skin rather than part of the virus. Pulling, cutting, or digging at it removes healthy tissue, spreads virus particles into the fresh wound, and is the most common way people turn a small wart into a scar and three new warts.

What does the core of a wart look like?

The centre of a wart usually looks like a small, dense, off-white or yellowish circle of hardened skin, ringed by rougher grainy tissue, with pinpoint black or dark red dots in the middle. It is easiest to see on a plantar wart after a shower, when the softened surface turns chalky white. Two details separate that centre from a callus: the skin lines, the fine ridges of your fingerprint or sole, run straight across a callus but stop dead at the edge of a wart, and a callus has no dark dots. If you pare the surface gently with a pumice stone, a callus thins evenly while a wart reveals more dots and starts to sting.

The anatomy of a wart, layer by layer

From the outside in, a wart is three things stacked. The top layer is hyperkeratosis, an overgrowth of the hard outer skin that gives the wart its rough, grainy feel. Below that sit the infected cells themselves, ordinary skin cells carrying HPV and dividing faster than their neighbours, which is what pushes the bump upward. At the base, small capillaries loop up from the dermis to supply the extra tissue, and those loops are what you see as black dots when they clot or bleed. The virus lives in the upper skin only, which is why the goal of any treatment is to clear that thickened infected tissue and let normal skin grow back, not to chase something deeper.

Are warts dangerous?

For the large majority of people, no. The common warts on hands and feet are benign. They are a cosmetic and comfort concern, not a health threat, and the American Academy of Dermatology classifies them as harmless skin growths. There are real exceptions, and they matter.

Anogenital warts are different and belong with a doctor

Anogenital warts, the ones that appear on or around the genitals and anus, are caused by different HPV strains and are a sexually transmitted infection. They are not the same growth as the common warts covered in this guide. They must never be treated with at-home devices or with over-the-counter wart products meant for hands and feet, because the skin there is thin and the strains involved need medical follow-up rather than removal alone. If a growth is in that area, stop reading treatment guides and book a healthcare provider or a sexual health clinic. They are common, they are treatable, and prescription options exist that no home product can match.

When a bump is not actually a wart

Skin cancer can occasionally resemble a wart. If a growth bleeds without being touched, grows quickly, changes color, develops irregular borders, or simply does not look like a typical wart, do not treat it at home. See a dermatologist. The same applies to any growth you are not sure about. Resources at Mayo Clinic are a useful starting point for understanding when a growth needs professional review.

Warts or something else?

Several common skin growths get confused with warts. Here is how each one differs.

↔ Swipe the table sideways to see the full comparison.

Wart vs skin tag

A skin tag is soft, smooth, and hangs off the skin on a thin stalk, often in skin folds like the neck, armpits, and groin. A wart is firm, rough, and sits flush on the skin, usually with black dots. Skin tags are not viral and are not contagious. For the full side-by-side, see our skin tags guide.

Filiform wart vs skin tag

Both hang off the skin on a narrow stalk, so this is the one comparison people genuinely cannot make by shape alone. Use the tip and the texture. A filiform wart ends in several thin rough fronds, like a tiny brush or a few threads bundled together, and it feels dry and gritty. A skin tag ends in one smooth rounded knob and feels soft and fleshy. Location helps too: filiform warts cluster around the mouth, nose, and eyelids, while skin tags favour the neck, armpits, groin, and under the breasts, where skin rubs on skin. The practical difference is contagion. A filiform wart is viral, so touching it and then shaving or touching another area can seed a new one, and a skin tag cannot do that.

Wart vs mole

A mole is a flat or slightly raised brown or black spot made of pigment cells, usually smooth and present for years. A wart is rough, often skin-colored, and caused by a virus. Moles should never be treated at home, because mole changes can signal melanoma, and a dangerous one cannot be told from a harmless one by sight. If you are unsure whether a growth is a wart or a mole, see our moles guide and, when in doubt, have a dermatologist examine it in person before any at-home removal is considered.

Wart vs corn or callus

A corn or callus is thickened skin from pressure or friction, common on the feet. The key tell: a callus has continuous skin lines running across it, while a plantar wart interrupts those lines and often has the tiny black dots. A callus is not contagious; a plantar wart is.

Halo, blue, and birthmark: the odd wart descriptions people search for

Most of the strange words people type about warts describe a colour or a ring, and each one has a plain explanation. Here are the three that come up most, and which of them should send you to a doctor.

What is a halo wart?

A halo wart is a wart with a pale ring of skin around it, and the ring almost always has a boring cause. On a treated wart it is macerated skin, the soft white flaking that salicylic acid or a plaster leaves behind on the healthy skin at the edge. On an untreated wart it can be a ring of callus built up where the bump rubs, or the pale halo that sometimes appears as the immune system starts clearing a wart on its own. There is one version that is not a wart at all and does matter: a brown or black pigmented spot with a pale ring around it is a pigmented lesion, not a viral growth, and it needs a dermatologist rather than any at-home method.

Why do some warts look blue or black?

Blue warts are usually warts with blood trapped inside them. The capillary loops that feed a wart sit very close to the surface, and when one clots or bleeds under the thickened skin the trapped blood reads as blue, purple, or near black through the overlying keratin. It happens most often after pressure, after knocking the wart, or a few days after a treatment. That is normal and it usually fades as the skin sheds. The exception is worth taking seriously: a blue or black bump that is new, that is growing, that has an uneven border, or that you have not confirmed is a wart needs an in-person look from a dermatologist, because pigmented skin cancers can present exactly that way.

Birthmark or wart, how to tell them apart

Timing separates them faster than appearance. A birthmark is present at birth or shows up in the first weeks or months of life, and it is made of pigment cells or blood vessels. A wart is an infection you pick up later, so it appears on skin that used to be clear, it grows over weeks, and it can be joined by others nearby. One birthmark does cause genuine confusion: an epidermal nevus is a birthmark made of skin cells that can look rough, raised, and warty, sometimes in a line or a streak. If a rough patch has been there as long as you can remember, treat it as a birthmark, not a wart, and have a dermatologist identify it. Nothing that has been on your skin since childhood should be treated at home.

What causes warts?

Warts are caused by HPV entering the skin, usually through a small cut, scrape, or area of softened skin. The virus is extremely common, and exposure does not guarantee a wart: whether you develop one depends heavily on your immune system.

How the virus spreads

HPV that causes common warts spreads through direct skin contact and through contact with surfaces a wart has touched, such as shared towels, locker-room floors, and pool decks. Touching one of your own warts and then another part of your body can spread it to yourself, which is why warts sometimes appear in a line or cluster. For the full breakdown of spread and prevention, see our guide on whether warts are contagious.

Why some people get warts and others do not

The immune system is the deciding factor. A healthy immune system often clears HPV before a wart ever forms, or clears an existing wart over time. People whose immune response is weaker tend to get more warts and keep them longer.

Warts in children and on the immune-compromised

Children and teenagers get warts far more often than adults, because their immune systems have not yet built up resistance to the common HPV strains and because they share equipment and close contact. People who are immunosuppressed, including those on certain medications or after organ transplant, also develop warts more frequently and more persistently. This is a documented pattern, not a theory.

Did you cause this? No.

You did not get a wart because you were unclean. Warts are a viral infection that anyone can pick up from ordinary contact, and getting one is not a sign you did anything wrong. The realistic goals are to treat the ones you have and to avoid spreading them.

Identify the subtype first. The subtype, not the bump, decides which treatment will actually work.

Treatment options

There is a clinical path and an at-home path. Both work for the right person and the right subtype.

Clinical treatment

Dermatologists treat warts with several options, each suited to different cases:

• Cryotherapy. Liquid nitrogen freezes the wart. Effective, especially for plantar warts, and usually needs several sessions.
• Cantharidin or stronger acids. An in-office application that blisters the wart so it lifts away.
• Electrosurgery and curettage. The wart is burned and scraped off. Good for stubborn single warts.
• Laser treatment. Reserved for warts that resist other methods or that are numerous.
• Immunotherapy. For widespread or resistant warts, the doctor stimulates the immune system to attack the virus.

Costs add up per session and per wart, which is why people with one or a few accessible warts often look at home first.

At-home treatment

For common, flat, and filiform warts in safe locations, at-home treatment is a reasonable first step. Over-the-counter salicylic acid is the traditional route and works slowly over weeks. Freeze kits chill the wart but can be hard to aim and can damage surrounding skin. The more precise at-home approach is to direct energy to the wart tissue itself so it is treated at the source and the skin renews on its own.

The OcuraLife Plasma Pen is the at-home device built for precise treatment of this category of growth. It delivers plasma energy at low power directly to the thickened tissue described earlier, so the raised growth is treated without spreading across healthy skin, and it runs at 9 power settings so you can match intensity to the subtype and location. That adjustability is not a spec sheet line. A thread-thin filiform wart beside the nose and a thick common wart on a knuckle need very different amounts of energy, and a fixed-power tool gives them the same, which is how people end up with a mark instead of clear skin. For the full method walkthrough, see our warts removal at home guide, and for the buyer-side method comparison see best at-home wart removal.

A note on subtype fit. Plantar warts, pressed deep into the sole, are the one subtype where cryotherapy often has the edge, and very stubborn plantar warts are worth a doctor visit. Common, flat, and filiform warts in reachable spots are where precise at-home treatment shines.

What to expect from at-home plasma pen treatment

Aftercare is simple: keep the area clean and dry, do not pick the scab, and protect the spot from the sun while it heals. Picking is the most reliable way to leave a mark and to risk spreading the virus, so leave it alone.

Do wart removal pens work?

Yes, for the right wart, and no for the wrong one, and the word pen is doing too much work because it covers three completely different tools. What decides the result is whether the tool matches the subtype, not the shape of the handle. Here is what is actually on the market and what each one can honestly do.

The three kinds of wart removal pen

Salicylic acid pens are a brush or felt tip that paints acid exactly on the wart instead of on the skin around it. The acid itself has the longest track record of any at-home wart treatment, and the pen format mainly improves aim. It is slow, several weeks of daily use, and it needs you to file the softened surface between applications.

Freeze pens deliver a chilled gas through a tip. They are quicker in principle, but home units do not get as cold as clinic liquid nitrogen, the tip is hard to keep on a small target, and an overshoot blisters healthy skin. They also do poorly on the thick plantar plug covered earlier, because the cold never reaches far enough through the hardened keratin.

Plasma and fibroblast pens work differently again, delivering a fine electrical arc to the surface of the growth so the raised tissue is treated in place. They are the most precise of the three on small, raised, reachable warts, and the most dependent on power control, which is exactly why the adjustable settings described above matter more here than on any other tool. None of the three belongs anywhere near anogenital warts, a growth you have not identified, or a lesion that is changing.

Do dermatologists remove warts with a fibroblast pen?

Some do, but it is not the standard first choice, and you should know what your clinic normally reaches for. The clinical workhorses for warts are cryotherapy, cantharidin, and electrosurgery, the three listed earlier. Fibroblast and plasma devices in a clinic setting are mostly marketed for skin tightening and for benign surface growths rather than for warts specifically. The closest clinical relative to a plasma pen is the electrosurgical hyfrecator, which also treats tissue with a fine electrical arc, at much higher power and with local anaesthetic. So the technology is genuinely used on skin by professionals. If a clinic offers you a fibroblast pen for a wart, it is fair to ask which device, how many sessions, and why they are choosing it over freezing.

When to see a dermatologist instead

Most warts never need a clinic, and it takes a few seconds to work out whether yours is one of them.

There is no downside to having a dermatologist confirm what something is. The at-home option is for the ordinary warts you already recognize. Anything ambiguous deserves a professional eye first.

FAQ

Frequently asked questions

Quick answers

The questions readers ask most about warts, answered directly.

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The bottom line

Warts are common, viral, and for most people harmless. The rough bump you found is your skin reacting to HPV, not a sign you did anything wrong, and there is no root hiding under it waiting to be dug out. The two things worth doing are the identification check (if it is anogenital, bleeding, changing, or you are unsure, see a doctor) and choosing a treatment that fits the subtype.

If you are confident your growth is an ordinary wart and you want it gone, the OcuraLife Plasma Pen was built for precise at-home treatment of this exact category of growth, and it is backed by a 90 day money-back guarantee if it does not suit your skin.

See real customer reviews, photos, and before-and-afters →

The OcuraLife Plasma Pen is a cosmetic device for benign, surface-level spots and is not a substitute for medical advice or diagnosis. If a spot is changing or you are unsure, check with a qualified professional.