When skin warts appear, it can seem as if the harmless growths came out of nowhere.
But 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.
In every issue of WebMD the Magazine, we ask our experts to answer readers' questions about a wide range of topics. In our May 2010 issue, we turned to WebMD's Skin Care Expert, Karyn Grossman, MD, to get advice on dealing with those pesky little bumps that so many of us have on our upper arms.
Q. I have lots of little bumps on my upper arms -- I don't like going sleeveless. What are they? Can I get rid of them?
A. Those little bumps are caused by keratosis pilaris, a common skin condition...
“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 do people get common skin warts?
If you have any type of skin wart, it means that you came in contact with a wart-causing virus sometime in the past, though it could have been months ago.
“People get warts from other people with warts, they don't get them from frogs and toads,” says Robert Brodell, MD, a dermatologist in Warren, Ohio. “The most common way is direct skin-to-skin contact, such as shaking hands with someone who has warts on their hand. You can also get the virus from inanimate objects, like towels that have been used by someone with a wart.”
The viruses are more likely to cause warts when they come in contact with skin that is damaged or cut. Getting a small scrape or biting fingernails may bring on wart. Similarly, cuts and nicks from shaving can provide an avenue for infection. This explains why men may have warts in the beard area, while women often have them appear on the legs.