How do periungual warts work?

Periungual warts are warts found under and around the fingernails and toenails that look like rough bumps with an uneven shape and surface. Warts are skin growths caused by the human papillomavirus, or HPV, according to WebMD.

Periungual warts are common in nail biters. In the beginning, they are the size of a pinhead, shiny, smooth, translucent and usually disconnected. They grow in weeks or months to the size of a pea, become rough, dirty brown, grey or black. The warts split open and become inflamed and tender. Method of treatment depends upon the severity of the warts. They may recur after treatment, according U.S. National Library of Medicine.