Warts are small, grainy skin growths with a rough texture, and they have a few telltale signs that set them apart from other bumps. The most reliable visual clue is tiny black dots scattered across the surface, which are small blood vessels that have clotted inside the growth. If you see those dots on a rough, raised bump, especially on your hands or fingers, you’re almost certainly looking at a wart.
What a Common Wart Looks and Feels Like
Common warts appear as firm, raised bumps with an irregular, rough surface. They can be as small as 1 millimeter or grow to several centimeters across. The texture is often described as grainy or slightly cauliflower-like, and the color tends to match your skin tone or appear slightly gray-brown. Running your finger over the bump, it will feel noticeably rougher than the surrounding skin.
The black dots are the single most useful feature for telling a wart from other skin growths. These dots are clotted blood vessels that form inside the wart as it grows. Not every wart displays them on the surface right away, but if you gently file or pare down the top layer of rough skin, they typically become visible. Most common warts show up on the fingers, backs of the hands, or around the nails, though they can appear on the arms and legs as well.
Warts That Don’t Look Like “Typical” Warts
Not all warts fit the classic raised, rough bump description. The type and location change the appearance significantly.
- Plantar warts grow on the soles of your feet and are pushed flat by your body weight, so they grow inward rather than outward. They often look like a thick patch of hard skin, which is why they’re frequently mistaken for calluses. The key difference: plantar warts hurt when you squeeze them from the sides, and they interrupt the natural lines of your skin (like fingerprints on your sole). A callus preserves those skin lines. Plantar warts also tend to be painful when you walk or stand.
- Flat warts are smoother, flatter, and smaller than common warts. They tend to appear in clusters, sometimes dozens at a time, on the face, forehead, or legs. Because they’re so flat and smooth, people often mistake them for acne or age spots.
- Filiform warts look completely different from what most people picture. They’re thin, thread-like projections that stick out from the skin, usually appearing around the lips, eyelids, or nose. They grow quickly and are easy to identify once you know what to look for because of their distinctive finger-like shape.
- Periungual warts grow around or under the fingernails and toenails. They can be particularly stubborn and may distort the nail as they grow, causing the nail to lift or become misshapen.
Wart vs. Callus vs. Corn
The confusion between warts and calluses or corns is one of the most common reasons people search for help identifying a growth, especially on the feet. All three produce areas of thickened, hardened skin, but the underlying cause is different. Calluses and corns form from repeated friction or pressure, while warts are caused by the human papillomavirus (HPV) infecting the outer layer of skin.
Here’s how to tell them apart. A callus is a broad, flat area of thickened skin with no clearly defined edge. It’s not usually painful unless the skin cracks. A corn is smaller and more focused, often forming on the tops of toes, with a hard center surrounded by inflamed skin. It hurts when you press directly on it. A plantar wart, by contrast, hurts most when you pinch it from the sides rather than pressing straight down. Look closely at the surface: if you can see tiny black dots or the natural skin lines (the ridges on your sole) go around the growth rather than through it, it’s a wart. Calluses and corns preserve those skin lines.
How Warts Develop
Warts are caused by HPV entering the skin through small cuts, hangnails, or areas where the skin is thin or damaged. The virus is common, and most people encounter it at some point, but not everyone develops visible warts. Your immune system often clears the virus before a growth appears.
When a wart does develop, it doesn’t show up immediately after exposure. There’s typically an incubation period of weeks to months between the initial infection and a visible bump. This delay is why it can be difficult to trace where or when you picked up the virus. Warts spread through direct skin contact or by touching surfaces that carry the virus, like shower floors, towels, or shared gym equipment. You can also spread warts from one part of your body to another, especially if you pick at or scratch a wart and then touch other skin.
Signs a Growth Might Not Be a Wart
Most bumps on the hands and feet that match the descriptions above are warts and are harmless, even if they’re annoying. But some skin growths that look unusual deserve closer attention. The ABCDE guidelines used by dermatologists help flag growths that could be more serious:
- Asymmetry: one half of the growth doesn’t match the other
- Border: the edges are ragged, blurred, or irregular
- Color: the color varies across the growth, with different shades of brown, black, red, or blue
- Diameter: the growth is larger than the size of a pencil eraser (about 6 mm)
- Evolving: the growth changes in size, shape, or color over time
A bump that bleeds easily, oozes, or doesn’t heal could also be something other than a wart. Red, rapidly growing bumps that bleed with minimal contact may be pyogenic granulomas, which are overgrowths of blood vessels that sometimes require a biopsy to rule out something more serious. If a growth doesn’t look or behave like a typical wart, or if you’re simply unsure, a dermatologist can give you a definitive answer quickly.
How Doctors Confirm a Wart
In most cases, a doctor or dermatologist can identify a wart just by looking at it. The rough texture, location, and presence of black dots are usually enough. For plantar warts, a provider may gently pare down the surface layer of skin with a scalpel to reveal the clotted blood vessels underneath, confirming the diagnosis.
When a growth doesn’t look typical, dermatologists can use dermoscopy, a handheld magnifying tool with a built-in light that makes the outer layer of skin translucent. This lets them see the internal structure of the growth, including blood vessel patterns that are characteristic of warts but invisible to the naked eye. In rare cases where the diagnosis is still uncertain, a small tissue sample can be sent for lab analysis, but this is uncommon for standard warts.
The vast majority of warts are identifiable at home using the features described above. If you have a rough, skin-colored bump with black dots on your hands or feet that hasn’t changed color or started bleeding, it’s very likely a wart. They’re one of the most common skin conditions, affecting an estimated 10% of the general population at any given time, and while they can be persistent, they pose no serious health risk.