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Viral Warts

  • Viral infections of the skin that are most common on the hands and feet
  • Symptoms are small bumps that appear on the skin individually or in clusters
  • Treatments include injections, topical medications, and cryotherapy
  • Involves dermatology, pediatric dermatology

Overview

While having warts can be annoying—even embarrassing—they are often treatable and not harmful. 

Common warts, flat warts, and plantar warts are viral infections of the skin (most originating from the human papillomavirus or HPV family, but not the strains associated with cancer).

“Viruses like to infect through cuts in the skin,” says Yale Medicine dermatologist Christopher Bunick, MD, PhD. “Picking of the warts (or biting them) can lead to spread of the virus, including around the mouths of kids.” 

Two common locations for warts in both kids and adults are the hands and feet. Palmar (hand) and plantar (feet) warts can prove very difficult to get rid of. “There are many treatments available, from over the counter to prescription, but perhaps the most important key is consistent attack against the wart until it is resolved,” says Dr. Bunick.

Ultimately, warts are benign. “They can be a nuisance, occasionally cause discomfort, and often people don’t like the way they look, but in the end they are not harmful,” he says.

What are the risk factors for developing viral warts?

Viral warts affect children and teens more than adults because their immune systems haven’t developed the antibodies to fight strains of HPV that cause warts. Eventually, though, the body will recognize the warts and do something about it.

Skin-to-skin contact, or skin that comes in contact with things that have been touched by others, is often what spreads the virus. So, it can help for people to avoid sharing such personal items as towels or pumice stones that touch the skin directly. Also encourage your child to wear flip flops when walking on a locker room floor or public pool area. Watching out for open cuts on such wart-prone areas as hands and feet can also help, so it’s best to quit habits like fingernail biting. Still, there really isn’t much one can do in the way of prevention because HPV is everywhere, Dr. Bunick says.

Though most people become immune to the viruses over time, usually by the end of the teenage years, some people may develop warts into adulthood, possibly because of certain genetic susceptibilities. Patients who are immunocompromised (such as those taking medications that suppress the immune system) may also see warts develop, but in general, the condition largely affects children.

How are viral warts diagnosed?

Doctors typically diagnose warts by examining suspected warts, which often develop near broken skin, such as where fingernails and cuticles have been bitten or picked. Doctors also look for small, rough bumps that may appear individually, or in clusters. They also check for pinpoint black dots, which are clotted blood vessels.

How are viral warts treated at home?

With time, viral warts will usually go away on their own. But when waiting isn’t an option—if the warts are painful, or if they are in a spot that’s causing embarrassment—there are over-the-counter treatments.

  • Salicylic acid: This can generally be found as a liquid, on pads or as a tape, and is applied directly to the wart nightly. These are available over-the-counter and are a good starting point for treatment; treatment can take several months.
  • Cryotherapy: These over-the-counter sprays, which freeze off the warts, are milder forms of the liquid nitrogen therapies you will find at the dermatologist.
  • Duct tape: Some people apply duct tape to the wart in much the same way you would salicylic acid treatments. Duct tape, if your doctor says it’s okay to try, can occasionally be helpful, probably because it creates irritation, which can stimulate the immune system to go after the warts, Dr. Bunick explains. Duct tape can also aid in removal of the thickened skin associated with warts, which can help to make treatments like salicylic acid more effective. 

How are viral warts treated by a dermatologist?

When warts don’t respond to at-home therapy and they are painful or causing embarrassment, a dermatologist may recommend one or more of the following methods of in-office treatment.

  • Cryotherapy: This is a more intense version of the over-the-counter option—liquid nitrogen is applied to the wart. Because this can be painful and often takes a few applications over several weeks, it’s not always ideal for small children. "The idea is to destroy the wart by freezing it,” says Dr. Bunick. But, it can be uncomfortable and can be difficult for little kids to tolerate.
  • Immunotherapy: This treatment tries to get the body to do what it would otherwise do naturally—find the wart and fight the virus that’s causing it. Doctors take a surface protein that most people’s immune systems have seen before —usually, the yeast known as candida—and inject a marker for the protein (not the yeast itself, but a substance the immune system will react to similarly) under the skin near the wart. The immune system recognizes the marker, is tricked into fighting it, and, hopefully, identifies the wart and fights that, too. It usually requires multiple injections, generally every two to four weeks. 
  • Topical immunotherapy: Dermatologists at Yale Medicine also employ topical immunotherapy, which uses a chemical that creates a rash in the skin, similar to a rash one gets from poison ivy: The body has an allergic reaction at the site of the wart, and the immune system kicks in to help fight off the wart virus.
  • Laser surgery: The use of an intense, targeted beam of light can help when other forms of treatment don’t. At Yale Medicine, laser is occasionally used for difficult cases but is generally considered a last resort.

Why do some warts not respond to treatment quickly?

“I like to tell my patients that warts are like a 100-layer brick wall,” Dr. Bunick says. “The virus lives at the bottom of the wall, and unless you get all 100 layers and the virus at the bottom, the wart will likely grow back." Therefore, he says, one of the most common reasons for treatment failure is not completing the full therapy needed to eliminate the virus at the base of the wart. For persistent warts, injections and topicals that stimulate one's own immune system to fight the virus are very effective. “This approach can be combined with traditional paring of the wart and cryotherapy to make a nice 1-2-3 punch against the wart,” says Dr. Bunick.

What makes Yale Medicine’s approach to treating viral warts unique?

Through clinical trials, Yale Medicine Dermatology can try new approaches to wart therapy. Our team of doctors and researchers are always searching for improved wart removal methods.