Warts are small, rough growths that appear on the skin. They are very common, especially in children and teenagers, but adults can get them too. If you have ever wondered how warts form, the answer starts with a virus and the way your immune system responds to it.
In this article, we explain clearly and simply how warts form, what happens inside the skin, and how they spread from one area to another.
What causes warts
Warts are caused by the human papillomavirus, often shortened to HPV. This is a very common virus. There are many different types of HPV, and some of them infect the skin on your hands, feet, face or other parts of the body.
Cutaneous warts are caused by HPV infecting the top layer of the skin. The virus does not travel deep into the body. It stays in the outer skin layer, which is called the epidermis.
Plantar warts, which appear on the soles of the feet, are simply warts that grow in a weight-bearing area. These can be painful because of pressure when walking .
How warts form in the skin
To understand how warts form, it helps to know what happens step by step.
1. The virus enters through a break in the skin
HPV cannot pass through completely healthy, intact skin. It needs a tiny opening. This might be:
- A small cut
- A scratch
- Softened skin after swimming or showering
- Cracked dry skin
These openings are often so small that you cannot see them.
When the virus enters through one of these breaks, it reaches the lower part of the epidermis.
2. The virus infects skin cells
Once inside, HPV infects keratinocytes. These are the main cells that make up the outer layer of your skin.
The virus inserts its genetic material into these cells. It then uses the cell’s own machinery to copy itself. As the infected skin cells grow and move upwards towards the surface, the virus multiplies inside them.
This is why warts gradually become thicker over time.
3. The skin starts to thicken
Because the infected cells are being pushed to multiply, the skin in that area grows faster than normal. This causes:
- Thickened skin
- A rough or grainy surface
- A raised bump
On the feet, pressure from walking can push the wart inwards instead of upwards. That is why plantar warts often look flat but feel painful when squeezed from the sides.
Under close inspection, small black dots may be seen inside a wart. These are tiny clotted blood vessels within the lesion.
4. The immune system responds
Your immune system eventually recognises that the cells are infected. In many people, especially children, the immune system clears the virus on its own.
In fact, most warts in children resolve naturally over time.
However, in some people, the immune response is slower or weaker. This can allow the wart to persist for months or even years.
Why some warts are harder to treat
Plantar warts on the feet are often more stubborn than warts elsewhere.
There are a few reasons for this:
- The skin on the soles is thicker
- Constant pressure pushes the wart deeper
- The immune system may not easily recognise the infection
Traditional treatments often focus on simply destroying the visible wart tissue through freezing or chemicals. However, these “tissue-damaging” methods can be ineffective because they fail to address the underlying virus, often leading to regrowth. In contrast, Swift microwave therapy is designed to be more effective by stimulating a precise immune response. By using controlled heat, Swift alerts the body’s immune system to the presence of HPV, leading to significantly higher clearance rates.
How warts spread on the skin
Now that you understand how warts form, the next question is how they spread.
Direct skin contact
Warts can spread through direct contact with another person’s wart or even your own wart.
If you touch or pick at a wart and then touch another area of skin, the virus can move to that area. This is called autoinoculation.
Shared surfaces
HPV can survive for a short time on surfaces. This means warts may spread in places such as:
- Communal showers
- Changing rooms
- Swimming pools
The virus is more likely to enter if the skin is softened and there is a small break in the surface.
Interestingly, some studies suggest that activities like swimming alone do not necessarily increase risk, but close contact and shared environments can contribute.
Spread within families
Warts are more common in children and can spread among family members. Sharing towels, footwear or close contact can increase the chance of transmission.
Why do children get warts more often
Warts are most common in school-aged children and teenagers.
This is likely because:
- Their immune systems are still developing
- They have closer physical contact with others
- Minor skin injuries are common during play
Over time, as the immune system learns to recognise the virus, the body becomes better at clearing it.
Common types of warts
Different types of HPV cause different looking warts.
- Common warts usually appear on the hands and fingers
- Plantar warts appear on the soles of the feet
- Flat warts are smaller and smoother
All of them follow the same basic process of infection, cell growth and skin thickening.
Key takeaways about how warts form
If you are searching for a clear answer to how warts form, here is the simple explanation:
- A virus called HPV enters through a tiny break in the skin.
- It infects the top layer of skin cells.
- The infected cells multiply more quickly than normal.
- The skin thickens and forms a raised, rough bump.
- The virus can spread through touch or shared surfaces.
In many cases, the immune system will eventually clear the infection. In others, treatment may help stimulate a stronger immune response and remove the wart more effectively.
Final thoughts
Warts may be common, but understanding how warts form helps explain why they can be persistent and why they sometimes spread.
If a wart is painful, spreading, or not improving, professional assessment can help determine the best course of action. Book an appointment with the Australian Wart Clinic today and receive Swift treatment.
