Warts are skin growths caused by some types of the human papillomavirus (HPV). Warts form when the virus infects the top layer of your skin and causes your skin cells to grow very fast.

Warts can spread when you come in contact with the virus. You can infect yourself again when you touch the warts and then touch another part of your body. You can infect others when you share towels, razors, or other personal items.

You are most likely to get warts in places where your skin is broken, such as through cuts, hangnails, closely bitten nails, or scrapes.

Some types of the virus thrive in warm, damp places, such as showers, locker room floors, and swimming pool areas. Warts that you get on your feet (plantar warts) are common in swimmers whose feet are not only moist and softened, but are also scratched and broken by rough pool surfaces.

You won't get warts every time you come in contact with the virus. But some people are more likely than others to get warts.

Warts are usually harmless. In most cases, they go away on their own within months or years. But if they spread or cause pain, or if you don't like the way they look, you may want to treat them.

There are several ways to treat warts. For example, you can:

• Use a home treatment to soften and remove the layers of the skin that form the wart. These treatments include salicylic acid (such as Compound W and Occlusal) or tape occlusion (such as duct tape). You don't need a prescription to use these products.
• Freeze the wart with a very cold liquid that can kill the virus. This is called cryotherapy. You can first try an over-the-counter medicine to freeze your wart. Or you can have your doctor freeze it for you.
• Use a medicine like cantharidin. This is medicine that is applied to your wart by your doctor.
• Have surgery that uses an intense beam (laser surgery) or an electrical current (electrosurgery) to burn off the wart. Or you can have the wart cut out (curettage).

If these treatments don't work, your doctor can try putting a medicine on the wart to trigger your immune system to kill the wart virus. Or they can inject medicines into the wart.

If you have diabetes, peripheral arterial disease, a weakened immune system, or a major illness, talk to your doctor before you use any over-the-counter wart removal products. You may not be able to use them.

The decision to treat your warts is up to you. But you might think about the cost and the time needed to treat them. In most cases, over-the-counter products you can use at home work as well as treatments done in your doctor's office. These home treatments cost less, cause little or no pain, and have a low risk of side effects or scarring. But they may take longer to work.

Treatments for warts don't always work. Even after warts shrink or go away, they may come back or spread to other parts of your body. This is because most treatments destroy the wart but don't kill the virus that causes it.

For some people, using salicylic acid or cryotherapy works better than no treatment. You may need to try several different treatments to find one that works for you.

Side effects depend on the type of treatment. But some can cause:

• Skin irritation, burning, and blistering.
• Pain.
• Scarring.
• Infection.
• Pigment changes.
• Nerve damage.

Your doctor might suggest that you treat your warts if:

• You have a wart that is getting worse and is easily irritated.
• You have a plantar wart that hurts to walk on.
• You don't like the way your wart looks.
• You are worried that your wart might spread to other people or other parts of your body.