Warts: Learn About Types, Treatments and Causes

What is Warts?

Warts have a rough texture and are caused by viruses, particularly one of several kinds of HPV (human papillomavirus).

The virus causes keratin, which is a hard protein on the top layer of the skin, to grow too fast.

Warts are not the same as moles. Moles are dark and may become quite large while warts are nearly always small and have the same color as the person’s skin.

The appearance of a wart can vary depending on what part of the body it is, as well as how thick the skin is. A wart that is located on the sole of the foot is known as a verruca.

Warts are skin growths that are caused by the human papillomavirus (HPV). There are more than 60 kinds of HPV, some of which tend to cause warts on the skin. HPV stimulates quick growth of cells on the skin’s outer layer. In most cases, common warts appear on the fingers, near the fingernails, or on the hands. Certain types of HPV can also cause warts to appear in the genital area.

Types of Warts

• Plantar warts: This type of wart usually appears as flesh-colored or light brown lumps that are flecked with small clotted blood vessels that appear as tiny black dots. Plantar warts appear on the soles of the feet.
• Genital warts: Genital warts can appear in the pubic area, on the genitals, in or around the anus, and/or in the vagina. They look like small flesh-colored, pink, or red growths. The warts may look similar to the small parts of a cauliflower or they may be very tiny and difficult to see. They often appear in clusters of three or four, and may grow and spread rapidly. They usually are not painful, although they may cause mild pain, bleeding, and itching. HPV infection is the most common sexually transmitted disease in North America and certain forms of the virus can cause cervical cancer.
• Flat warts: This type of wart is more common in teens and children than in adults. Flat warts are smoother, flatter, and smaller than other warts and they generally occur on the face. Flat warts also can appear on the legs, especially among females.

Warts are caused through direct contact with HPV, which is contagious. HPV may spread by person-to-person contact or through direct contact with an object used by a person with the virus. The virus that causes warts also can spread to other places on the body of the person with warts.

Causes of Warts

Common warts are actually an infection in the top layer of skin, caused by viruses in the human papillomavirus, or HPV, family. When the virus invades this outer layer of skin, usually through a tiny scratch, it causes rapid growth of cells on the outer layer of skin – creating the wart.

“HPV is ubiquitous,” says dermatologist Conway Huang, MD, an associate professor of dermatologic surgery and cutaneous laser surgery at the University of Alabama at Birmingham. “We all come in contact with it,” throughout our lives, such as when shaking hands, turning doorknobs, or typing on keyboards.

Scientists have identified more than 100 unique types of the virus. And most people will have at least one common wart at sometime in their lives, usually on their hands.

Certain forms of the virus are more likely to cause skin warts on the hands. Other forms of HPV are more likely to cause genital warts, although some strains of the virus can cause both.

How Are Warts Treated?

In most cases, warts found on the skin are harmless and can disappear without treatment. However, genital warts should be evaluated by a doctor.