A wart is a rough growth on the skin caused by a type of virus called a human papilloma virus (HPV.) There are over 100 different types of HPV. The types of HPV that cause non-genital warts are different from the types of HPV that can cause cervical cancer and other types of cancer.
Anyone can get a wart, but some people are more prone to get them. They are more common in children, in people who bite or pick at their nails or cuticles, and in those that have a compromised immune system. Because they are caused by a virus, they are contagious and can be transferred by touch. You can get one by directly touching a wart or by touching something that has come in contact with a wart. You are more likely to get a wart if you have a cut or a scrape in your skin. Excessive moisture can cause small breaks in the skin barrier, so common areas to contract them are around pools, hot tubs, or locker rooms. Each person’s immune system responds differently to the HPV virus, which explains why not everyone who contacts a wart develops one.
Common warts feel rough to the touch, and they often have tiny black dots on their surface. These are often referred to as “seeds,” but they are actually small blood vessels. They can appear anywhere on the body, but they are most common on the hands and knees.
Plantar warts occur on the bottoms of the feet. They tend to grow deep, and they are also often surrounding by a thick callus. Because they are often found on the weight-bearing parts of the feet, they tend to be more painful than common warts. Some of my patients describe their plantar warts as walking around “with a pebble in my shoe.”
Mosaic warts are a cluster of smaller warts grouped together. They are most often seen on the palms and soles.
Flat warts are often flesh-colored, round, and flat-topped. The can occur in clusters and can range from a few to hundreds. They can be arranged in a line, as a result from scratching, trauma, or shaving.
Filiform warts have long, slender projections, and they are most common on the face around the eyes, nose, or mouth.
Warts may go away without treatment, especially in children. Although most warts are harmless, they may be painful and disfiguring, and they are contagious. For these reasons, dermatologists treat them. There are many treatments for warts; however no treatment is uniformly effective. It often takes multiple treatments to get rid of warts, especially in areas with thicker skin, such as the bottoms of the feet.
Cryotherapy involves freezing the wart with liquid nitrogen to destroy the cells that contain the wart virus and cause a local immune response. This can be done in your dermatologist’s office. There are also over-the-counter freezing kits available, but they do not freeze the tissue as cold or fast as the in-office treatment does. Side effects may include discomfort, blistering, or discoloration of the surrounding skin. Treatments are repeated every 2-3 weeks until the wart is gone.
Warts may also be treated by curettage and/or cautery. Curettage involves scooping out the wart with a sharp tool. This may be followed by burning the wart with a cautery device. This is a good treatment for filiform warts, however this technique may lead to scarring.
Cantharidin is a medication derived from the blister beetle, and it is often called “beetlejuice.” Cantharidin is painted on the wart in the dermatologist’s office and covered with a bandage or tape. The treated area with develop a blister that will heal in a week or two. Treatment is repeated every 2-3 weeks. This procedure is painless when the medication is applied; however, the resulting blister can be uncomfortable during the healing process.
Salicylic acid is a very common treatment for warts, and some formulations can be purchased over-the-counter to be used at home. Many patients try these over-the-counter preparations, as they are inexpensive and painless. However, it may take months or more to cure the wart with salicylic acid. A dermatologist can also prescribe a stronger concentration of salicylic acid to be used on the wart, and this is often compounded with 5-fluorouracil, another topical agent that can help prevent wart-infected cells from dividing and proliferating.
Bleomycin is a medication that can be injected directly into the wart. This causes destruction of the treated area, which may stimulate an immune response. These injections are often painful. Other side effects may include redness, burning, and swelling. This is not a good treatment for warts on the fingertips, as it may cause nail damage and loss.
Immunotherapy is a type of treatment that involves stimulating the patient’s own immune system to fight off the wart. This can be done in several different ways. The wart can be injected with Candida antigen, a type of yeast. Another option is to use a chemical called diphencyprone (DCP) that is applied in the dermatologist’s office to generate a mild allergic reaction. Alternatively, a prescription cream called imiquimod may be applied topically at home. Side effects of immunotherapy may include redness, itching, and local irritation of the skin. Injections of Candida may be painful. Disadvantages of imiquimod treatment include high cost and long treatment duration.
In addition, several different types of lasers can be used to treat warts. Laser treatment is usually used on warts that have been recalcitrant to other therapies. This treatment is costly, and it can be painful.
If you have a wart that you want treated, see your dermatologist to discuss what treatment would be best for you.
- National Cancer Institute – HPV and Cancer
- Dermatology Online Journal- Cantharidin
- Pubmed Health- Salicylic Acid
- Pubmed Health- Bleomycin
- JAMA Dermatology- Immunotherapy with Candida antigen
- Journal of the American Academy of Dermatology- Diphencyprone
- Pubmed- Imiquimod for Non-genital Warts
- American Academy of Dermatology- Warts