Warts are small, rough skin growths caused by human papillomavirus (HPV) that hijack your skin cells to reproduce. They’re noncancerous, and most of them eventually go away on their own, but depending on where they show up, they can cause pain, spread to other parts of your body, and make everyday activities uncomfortable. About 90% of HPV infections clear spontaneously within two years as your immune system fights them off.
How Warts Change Your Skin Cells
HPV enters through tiny breaks in the skin and infects keratinocytes, the cells that make up the outer layer of your skin. Once inside, the virus essentially reprograms those cells. It disrupts the normal process of cell maturation, keeping infected cells in a more “stem-like” state where they keep dividing instead of maturing and shedding off naturally. This forced overgrowth of skin cells is what creates the raised, rough bump you see on the surface.
The virus also recruits its own blood supply. As a wart grows, tiny blood vessels called capillaries feed into it. These capillaries often become clotted, producing the small black dots that many people mistake for seeds. Those dots are actually dead, clotted blood vessels visible through the thickened skin.
What Warts Feel and Look Like
Not all warts behave the same way. The type of HPV strain involved and the location on your body determine how a wart looks, feels, and whether it causes any pain.
Common warts typically show up on your hands and fingers. They feel like rough, firm bumps ranging from the size of a pinhead to a pea. They’re usually painless unless they’re in a spot that gets bumped or pressed frequently.
Plantar warts form on the soles of your feet, often at pressure points. Because your body weight presses down on them, they tend to grow inward rather than outward, and they can become quite large. Walking or standing pushes the wart deeper into the skin, which is why plantar warts are the type most likely to hurt. Some people describe the sensation as walking on a pebble.
Flat warts are smaller and smoother than other types. They can appear anywhere but tend to grow in clusters of 20 to 100 at a time, often on the face, arms, or legs. Individually they’re barely noticeable, but in large numbers they can be cosmetically frustrating.
Filiform warts have a distinctive finger-like or tooth-like shape, sometimes on a narrow stalk. They’re most common on the face and neck and tend to bother people more for their appearance than for any physical discomfort.
Mosaic warts are white, pinhead-sized, and cluster together on the balls of the feet or under the toes. They’re flatter than plantar warts and rarely cause pain when walking, but they can spread to cover a larger area over time.
How Warts Spread
Warts spread through direct skin-to-skin contact with an infected area. You can also pass the virus to other parts of your own body, a process called autoinoculation. Picking at a wart on your hand, for instance, and then touching your face gives the virus a chance to set up a new infection. Biting your nails when you have a wart near the nail bed is a common way they spread to multiple fingers.
The virus thrives when skin is damp or damaged. Shared surfaces like pool decks, locker room floors, and shower stalls are common sources of plantar wart infections because the skin on your feet softens in wet environments, making it easier for the virus to get in through small cracks. A person carrying HPV can spread it even when they have no visible wart.
Why Some People Get Warts and Others Don’t
Nearly everyone encounters HPV at some point, but not everyone develops visible warts. The difference comes down to how effectively your immune system recognizes and attacks the virus. Two branches of your immune system play key roles: natural killer cells that respond early and T cells that mount a targeted, longer-lasting defense.
When researchers compared warts that were shrinking on their own to warts that persisted, the regressing warts contained significantly more T cells, particularly the type that coordinates the immune response. The surrounding skin cells also showed more activation signals, essentially calling in reinforcements. In warts that didn’t regress, immune cells were present but far less active, with roughly three times fewer cells capable of destroying infected tissue.
This is why people with weakened immune systems, whether from conditions like HIV or from medications that suppress immunity after an organ transplant, are more likely to develop persistent or widespread warts. Their immune systems struggle to mount the aggressive, targeted response needed to clear the virus from infected skin cells.
Children and teenagers get warts more often than adults, likely because their immune systems haven’t yet built up defenses against the many HPV strains circulating in the environment. For most healthy people, the immune system catches up and clears the infection without treatment.
Do Warts Turn Into Cancer?
The HPV strains that cause common skin warts are not the same strains linked to cancer. There are over 200 types of HPV, and they fall into low-risk and high-risk categories. The ordinary warts you find on your hands, feet, and face are caused by low-risk strains that very rarely cause anything beyond the wart itself.
Twelve specific high-risk HPV types are associated with cancers of the cervix, throat, anus, and genitals. These high-risk strains don’t produce the rough, visible bumps you’d recognize as a wart. Instead, they cause infections that persist silently for years, sometimes leading to precancerous changes in tissue. The common wart on your finger and the HPV infection linked to cervical cancer are caused by entirely different viral strains with different behaviors.
Low-risk HPV types can cause genital warts, which look different from common skin warts. They may appear pearly, flat, or cauliflower-shaped. While genital warts themselves rarely become cancerous, having them means you’ve been exposed to HPV through sexual contact, and co-infection with a high-risk strain is possible.
What Happens if You Leave Them Alone
Most warts are a waiting game. Because about 90% of HPV infections resolve on their own within two years, many warts will eventually shrink and disappear without any treatment. Your immune system gradually recognizes the infected cells, destroys them, and the wart fades.
The practical problem is that warts can be uncomfortable or embarrassing while you wait. Plantar warts can make walking painful for months. Warts on your hands can interfere with gripping objects or make you self-conscious. Flat warts on the face, especially in large clusters, affect self-esteem. And during the time a wart is active, it can spread to new areas on your body or to other people.
Periungual warts, which grow around or under the fingernails and toenails, deserve particular attention. They can lift the nail from the nail bed and cause structural damage that persists even after the wart resolves. They’re also notoriously stubborn because the nail provides a protective shield that makes both immune access and treatment more difficult.