Warts are small, benign skin tumors caused by various strains of the human papillomavirus. They are a common affliction of children and teenagers. The virus enters the skin through direct con-tact with another infected person or with a warm, moist surface (such as a locker-room floor) where infected skin has been shed. Warts eventually disappear as the immune system recognizes and eliminates the papillomavirus, but this process may take many months or even years. If not treated, the virus – and the warts it causes – may spread from its initial location (usually the hands)to other parts of the body or (less commonly) to other people.

Warts come in three basic forms:

Common warts appear as round, firm bumps on the skin with a sharply defined margin and a slightly roughened surface. If picked or pared with a scalpel, they will bleed actively. Common warts are generally found on the hands (especially around the edges of fingernails) and occasionally on the legs (most frequently around the knees).

Plantar warts occur on the soles of the feet, virtually always over pressure points(particularly on the heel or ball of the foot). They can be bothersome or even painful, since a callus can build up around the wart and create uncomfortable pressure, which is particularly noticeable while walking or running. Flat warts, which are flat-topped and flesh colored, are seen most often on the backs of the hands or on the face, sometimes in small clusters or in a line.

(Genital [or venereal] warts, which are also caused by strains of the human papilloma virus, behave and are treated differently from the other types of truest mentioned here. They can have more serious long-term con-sequences.)

While warts eventually go away on their own, removing them when possible to prevent them from spreading is wise. The method chosen will depend on the size and number of warts, their location, and the age (and level of cooperation) of the child. Whatever method is used, it is important to encourage your child not to pick or pull at the warts to prevent them from spreading.

Various weak acid formulations, available in both over-the-counter and prescription varieties that can be applied at home, are a slow but painless approach for both common and plantar warts. The medication will work best if the wart has first been pared down to re-move the thick outer layer of dead skin. A physician can do this with a scalpel, or you can use an emery board at home (one not used for any other purpose, in order to prevent the virus from spreading). If the wart bleeds a little, don’t pare any further but don’t worry. This may actually allow white blood cells to interact with the wart virus and speed up the immune response.

The wart site is soaked in warm water for a few minutes, and then a drop of the acid solution (for example, Duofilm) is applied onto the wart surface, allowed to dry into a film, and then covered for 24 hours. A variation of this is the salicylic acid plaster, which contains medicine and self-adhering covering in one package. These are usually left in place for 8 hours out of the day. Either for-mat will require 6 to 12 weeks of daily use.

For a more rapid response, your child’s primary-care physician or a dermatologist may be able to destroy one or more warts directly. Liquid nitrogen applied directly to a wart with a cotton swab feels very cold and stingy while the wart is being frozen, after which the area turns pink and aches for several hours. Eventually a dark blister will form, and the wart will peel away on its own.(Your child should be encouraged not to do this himself. This method is appropriate for a few warts on areas of skin that aren’t too sensitive (such as the back of the hand), but after the first experience your child may balk at having freezing done repeatedly, especially if fingertips (where there is an abundance of nerve endings) are involved.

An even more direct approach in the doctor’s office involves a shot of local anesthetic under the wart, followed by curetting (scraping the wart out of the skin with a sharp instrument) and then using an electrical instrument to cauterize the base. The dark crater that re-mains must be protected with a small dressing to prevent infection. Flat warts can be managed with topical medications (such as Retin-A) rather than acids, freezing, or burning. This is particularly important when they are present on the face.