Warts are small skin growths caused by the human papilloma virus (HPV), which infects the top layer of skin. There are more than 40 different types of HPV. It can be transmitted from one person to another either by direct contact, or indirectly when both people come in contact with a surface, such as a floor or desk. People may come into contact with HPV by walking barefoot in public places, such as gyms and shower floors. HPV also can be transmitted in the same person from one spot on the body to another. It is easier for HPV to infect a person when the person's skin is scratched or cut.
Warts can appear at any age but are more common in older children and are uncommon in the elderly. A wart's appearance varies with its location and the type of virus that has caused it. For example, flat warts commonly appear on the face, neck, chest, forearms and legs. Most warts go away after a year or two, but some last for years or come back after going away.
Warts can itch or bleed. When warts are located in areas that are rubbed against clothing or bumped frequently, they can become irritated and the skin around them can become painful. Warts are not cancerous.
The two types of warts seen most often are common warts and plantar warts.
- Common warts have a rough surface and well-defined borders. They are round or irregular in shape and range from 2 millimeters to 10 millimeters wide (the size of a pencil eraser or smaller). Common warts are firm and can be light gray, yellow, brown or gray-black. They occur most often near the fingernails and on the backs of the hands, but they also can appear on the elbows and knees. Common warts usually do not hurt.
Plantar warts appear on the bottom (sole) of the foot. They are flattened by the pressure of standing on them and can be dotted with tiny, clotted blood vessels that look like dark pinpoints. Plantar warts often are painful, especially when they're on a weight-bearing part of the foot. Corns look different than plantar warts because they don't have the pinpoint dark spots. Plantar warts may require vigorous, repeated treatment before they go away.
Other types of warts include:
- Genital warts appear on and near the genitals, as well as inside the vagina and on the cervix in women.
- Cervical warts appear on the cervix and sometimes develop into cervical cancer.
- Mosaic warts appear on the feet. They are groups of many small, closely set plantar warts.
- Filiform warts appear on the eyelids, face, neck or lips. They are long, narrow growths.
- Flat warts appear on the face and along scratch marks. They are smooth, flat-topped, yellow-brown papules and are more common in children than in adults.
- Pedunculated warts appear on the head and neck, scalp and beard and are shaped like cauliflower.
A doctor usually can diagnose warts by looking at them. Sometimes, the doctor will have to take some tissue from a wart and analyze it under a microscope.
It is difficult to prevent warts. You can reduce your chances of getting warts by avoiding skin contact with existing warts and with contaminated floors, such as those in locker rooms.
Most warts disappear within a year or two, even if they are not treated. Many people choose to have warts treated either because of minor pain or for cosmetic reasons. Treatment depends on the location of the wart, its type and size, a person's age and health, and his or her willingness to follow through with repeated treatments.
You should talk to your doctor before trying to treat your warts. Over-the-counter liquids and patches containing salicylic acid can decrease the size of a wart, but they should not be used on the face or genitals. Your doctor may treat a wart by applying certain medications or acids, freezing it (cryotherapy) or surgically removing it.
When To Call a Professional
If you think you might have a wart, you should show it to your doctor at your next visit to make sure it is a wart and to discuss treatment.
Seek help if your wart causes pain, bleeds easily, spreads easily to other areas of the body or comes back, or if you want the wart removed for cosmetic reasons. You also should see your doctor if you develop genital warts, so they can be treated.