What Causes Warts and How Can You Get Rid of Them?

None of us have skin that is entirely free of blemishes and flawlessly smooth. Our various freckles and moles, birthmarks, calluses, and stretch marks make us uniquely ourselves. And for the most part, many lumps, bumps, or spots are harmless.

Another type of growth that can show up on the skin is warts. Warts are common, raised bumps that are rarely painful or irritating. Despite being benign, warts are skin infections caused by human papillomavirus (HPV). And if one pops up, you may want to remove it before it can spread to other people or parts of your body.

Here's what to know about what causes warts and how you can treat them.

The Different Types of Warts

According to the National Library of Medicine, warts are infections caused by the human papillomavirus (HPV). They can appear on different body parts as benign fleshy overgrowths of skin. They do not often cause symptoms but are contagious and can spread HPV. In some cases, people may find their warts to be unappealing.

There are different types of warts, primarily categorized according to where they show up and how they appear on the body. The American Academy of Dermatology (AAD) describes five different types of warts:

• Common warts: Also known as verruca vulgaris, common warts typically grow on the fingers, near the nails, or on the backs of the hands. They are most common among children and can present as rough bumps, sometimes with black dots, or "seeds," in the middle.
• Plantar warts: Typically growing on the sole, or the plantar surface, of feet, plantar warts may be painful. They can also grow in clusters and have seeds in the middle.
• Flat warts: Flat warts tend to be smaller and smoother than other types but may grow in large numbers (anywhere from 20 to 100). Children usually develop flat warts on their faces. Adults may likely get them under their beards and find them on their legs.
• Filiform warts: Filiform warts have a base where strands look like threads sticking out. They often grow quickly and show up on the face, generally around the eyes, mouth, and nose.
• Genital warts: Also called condylomata acuminata, genital warts appear flesh-colored and flat or bumpy (like cauliflower). Genital warts can appear near the vaginal or cervical areas, on the vulva, inside the vagina, or around the anus. They can pop up on the tip of the penis, around the anus, or on the scrotum, thigh, or groin.

What Causes Warts?

The culprit behind all types of warts is HPV, a group of viruses that spread through skin-to-skin contact or sexual contact. What kind of wart you may develop depends mainly on the HPV strain you are exposed to. For example, while some HPV strains preferentially cause plantar warts, other strains are likely to cause common warts.

"Typically, [warts] are caused by direct contact with HPV-infected skin or fomites [objects or materials that carry infection]," Amie G. Sessa, MD, a dermatologist at MedStar Washington Hospital Center in Washington, DC, told Health. "When the virus infects the basal layer of the epidermis and starts to divide, warts are the result."

HPV can infect the skin when it is broken. So, if you have cracks in your skin from dryness or a cut from an injury, that is an opening for HPV to spread. Also, people with weakened immune systems, children, and the elderly are more likely to develop warts than others.

How Can You Treat Warts?

There are a few reasons why you may consider getting rid of warts. Because HPV is contagious, you can spread the infection to other people or parts of your body. Some HPV strains also increase your risk of certain cancers, like cervical, anal, and head and neck cancers, according to the World Health Organization (WHO) and the Johns Hopkins Medicine Health Library. You can treat some warts at home or visit a healthcare provider to remove them.

At Home

Unlike other dermatological concerns, you can often treat warts at home with over-the-counter products if they are not growing on your face or genitals. The AAD suggests a couple of methods:

• Salicylic acid: Liquids, ointments, sprays, bandages, and pads containing salicylic acid can help remove some warts. Most products indicate how long you should continue using them, but removing the wart can take several weeks.
• Duct tape: Believe it or not, in some cases, duct tape may be able to remove some warts. The sticky adhesive irritates the skin, causing your immune system to react, eradicating the virus. However, the AAD notes that there are conflicting studies on the efficacy of this method.

At the Dermatologist

If your wart appears on the face or genitals or is particularly stubborn, you may want to visit a dermatologist. Per the AAD, there are several different methods that dermatologists use to get rid of warts:

• Cryotherapy: A treatment where healthcare providers attempt to freeze off the wart, which involves applying liquid nitrogen that destroys the wart tissue and causes it to slough away later. Some brands make over-the-counter cryotherapy treatments, allowing you to freeze off the wart at home. However, those are not the same kind of cryotherapy options available at your dermatologist's office. They are weak treatments, so you should consult your healthcare provider before attempting cryotherapy.
• Cantharidin: A blistering treatment that sloughs off the wart by forming a blister underneath the infection.
• Electrosurgery: A burning treatment that uses heat to remove the wart.
• Curettage surgery: A method that uses a small, sharp knife to get rid of the wart.

For genital warts, as well as all types of warts, a dermatologist may prescribe medications. According to the Centers for Disease Control and Prevention (CDC), those medications include Condylox (podofilox), a gel that stops wart cells from growing; Zyclara and Aldara (imiquimod), topical solutions that enhance your immune system against HPV; or an ointment containing green tea extract, called Veregen (sinecatechins).

Preventing Warts

Preventing warts is tricky because HPV is a prevalent virus that many of us come into contact with at some point during our lives.

"HPV is a virus that can live inside normal-appearing cells, without causing warts to [visibly] grow," said Dr. Sessa, who added that some risk factors—for example, being immunocompromised—can suddenly cause the virus to divide actively.

Also, the latency period of HPV can further complicate prevention. The virus can incubate for two to six months before appearing as a wart on your skin.

There are, however, a few prevention techniques to give your skin a fighting chance, per the AAD. Those include:

• Avoiding touching other people's warts
• Designating specific personal items—like towels, nail clippers, and razors—to people living in the same house
• Cleaning and covering scrapes or cuts
• Washing hands regularly and often
• Preventing dry or cracked skin
• Putting an end to nail biting or cuticle picking
• Wearing flip-flops or shower shoes in public locations, including locker rooms, pool areas, and showers