An Overview of Warts

illustration of a wart
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Warts are benign (non-cancerous) tumors of the epidermis (the top layer of the skin) caused by the human papillomavirus (HPV). They look like small, fleshy bumps across the surface of the skin. Warts are extremely common. They most often occur on the hands, feet, and genitals. Warts normally resolve spontaneously but the time it takes for this resolution is variable, so most people opt for treatment.

Verruca is another name for wart.

Symptoms

Warts are small, raised, fleshy bumps that appear across the surface of the skin. They are typically skin-colored, but may also be shades of white, pink, yellow, or brown.

Warts normally grow out of the skin in cylindrical columns. These columns do not fuse when the wart grows on thinner skin, such as the face. On thicker skin, however, the columns fuse and are packed tightly together giving the surface the typical mosaic pattern.

Black dots can sometimes be seen in a wart. These are actually blood vessels that have grown rapidly and irregularly into the wart and have clotted off or thrombosed. They are not "seeds" of the wart as one myth has stated.

The Wart Root Myth

Contrary to popular belief, warts do not have "roots." They only grow in the top layer of skin, the epidermis. When they grow, they can displace the second layer of skin, the dermis, but they do not grow into the dermis. The underside of a wart is actually smooth.

There are many different types of warts:

  • Common warts (verruca vulgaris): These warts are most common on the hands, elbows, and knees, though they can occur anywhere. Common warts are raised with a rough, pebbly-textured surface.
  • Plantar warts (verruca plantaris): Plantar warts appear on the weight-bearing portions bottoms of the feet. They are rough and may look like a callous. Plantar warts often become uncomfortable when walking or standing. When they grow together into a cluster, they're referred to as mosaic warts. In this case, they're often more painful and difficult to treat.
  • Flat warts (verruca plana): Also called plane warts, these tiny warts come in clusters of a few dozen to hundreds. They have smooth flat or rounded tops. Flat warts are common on the backs of the hands, the face, legs, and other sun-exposed areas.
  • Filiform warts (verruca filiformis): These unusual-looking warts grow in tall, thread-like or spiky columns that protrude from the skin. They most often appear on the face, especially around the eyes, nose, and mouth.
  • Periungual warts: These rough, irregularly-shaped warts develop around the fingernails and toenails. These warts may extend underneath the nail, causing pain and disrupt normal nail growth.

Causes

The virus responsible for warts is the human papillomavirus (HPV), a double-stranded DNA virus. The virus resides in the bottom layer of the epidermis and replicates in a way in which the appearance is very similar to normal-looking skin. The HPV virus is incredibly common.

Different subtypes of HPV cause different types of warts. HPV is also the virus responsible for genital warts. Some human papillomavirus subtypes can cause cervical cancer and other more obscure types of wart-related cancers.

Warts can occur in people of all ages but occur most commonly in children and young adults.

Warts are contagious. They spread through direct skin contact with a wart, or by touching something that is harboring HPV.

For example, warts can be transmitted by shaking hands with someone who has a wart on their hands or by using a towel that had been used by someone with a wart.

They can also be picked up from walking barefoot across the ground where the virus has been shed by another person. People who spend time barefoot in places like gyms are more susceptible.

Warts can also be transmitted from one area of the body to another.

The human papillomavirus is incredibly common. Most people are exposed to it at some point in their lives, and will never develop a wart.

When there is a small break in the skin, the virus can enter the body. In many cases, the immune system can fight off the virus and a wart does not develop.

Some people are more prone to getting warts than others. It appears that a person's susceptibility to warts and the time it takes for them to go away is related to the individual's immune system. People who have immune-related diseases such as AIDS and lymphoma—or those who are receiving chemotherapy—tend to have more warts that last longer.

Diagnosis

Most warts can easily be diagnosed by a physician with a visual inspection.

If there's a suspicion that the growth isn't a wart but is instead skin cancer or a precancerous growth, your doctor will order a skin biopsy. During a skin biopsy, a small piece of the lesion is removed and inspected under a microscope.

You should see a physician any time you, or your child, have a growth that you can't identify. Also, see a doctor if warts are large or growing rapidly, multiplying, or if they're itchy, bleeding, or painful.

Warts that develop on the face or on the genital area should always be seen by a physician.

Treatment

Most warts resolve within weeks or months even without treatment, but some may take many years or decades. Most people do not wish to wait for this to happen, either because the warts are uncomfortable or for cosmetic reasons.

Many warts can be treated with simple over-the-counter (OTC) remedies, but for warts that are resistant to these therapies, there are other effective treatment procedures that can be done at the doctor's office.

Salicylic Acid

Salicylic acid is a very common and effective over-the-counter treatment. It can be found in several forms, including a thick oil or incorporated into an adhesive plaster form.

Some examples of salicylic acid wart removers include:

  • Compound W
  • Dr. Scholl's Clear Away
  • DuoFilm
  • Wart-Off

You can ask your pharmacist for help choosing an OTC wart removing product.

The best way to use salicylic acid is to first pare the wart with a blade, pumice stone, emery board or small scrub brush. Soaking the wart in warm water will aid in the absorption of the medicine.

Salicylic acid is applied to the wart and allowed to dry. The normal surrounding skin may be protected with petroleum jelly, and you may wish to outline the wart with this prior to treatment to avoid treating normal skin surrounding the wart.

Occluding the treated wart with a band-aid or piece of tape also improves the absorption of the medicine, and can decrease the chance the medicine will get on normal skin. Make sure to wash your hands after application and avoid contact of the treated area (for example, if on your fingers) with your eyes.

Salicylic acid requires consistent application. Applications should be repeated daily, ideally around shower or bath time.

Duct Tape

An increasingly-used home remedy for warts is duct tape. To do this, duct tape (any color) is applied to the wart and kept in place for six days. After this period of time, you should soak the wart and pare it down with an emery board or file to remove the top layer.

After waiting 24 hours, duct tape can again be applied for another six days. This may need to be repeated depending on the size and location of the wart.

Studies have shown mixed results with duct tape, but it is a home remedy with few side effects.

Prescription Medications

In cases where over-the-counter products aren't effective, there are other treatment options available by prescription. These medicines may be applied to warts or injected into them. They include:

These treatments should be supervised by a health care provider.

Cryotherapy (Freezing)

Cryotherapy (freezing) is another effective treatment for warts. A healthcare provider applies liquid nitrogen—as a spray or on a cotton swab—to the wart. This freezes and kills the affected cells.

The connective tissue is not destroyed; therefore, the lesion usually heals without significant scarring.

The human papillomavirus is not killed by cryotherapy and is released into the surrounding tissue allowing the immune system to kill it.

A blister typically forms on the site treated, crusts over, and falls off. Since blisters are painful to walk on, cryotherapy is not the first choice for warts on the bottom of the foot (plantar warts).

Options for Resistant Warts

Some warts do not seem to respond to repeated treatments with topical medicines, cryotherapy, or even duct tape. In this case, your doctor may recommend cautery (heat therapy) or surgically removing the wart. The area beneath the wart is usually numbed with lidocaine before surgery is done.

The combination of Aldara (imiquimod 5%) plus duct tape may also be helpful with recalcitrant warts.

Finally, further treatments such as pulsed dye laser, photodynamic treatment, or injecting Candida antigen, other antigens, dinitrochlorobenzene, or vitamin D directly into the wart have all been tried.

In one study with resistant warts, vitamin D had an almost a 90% complete success rate for recalcitrant warts.

A Word From Verywell

Warts are very common, especially in children and young adults. They are caused by direct contact with a virus. In time, most warts will go away on their own, yet they can be annoying and unsightly when left untreated.

Many options are available to get rid of warts, from over-the-counter topical preparations to freezing or burning in the clinic.

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