What is poliosis? Poliosis is when a person is born with or develops a patch of white or gray hair while otherwise maintaining their natural hair color. It can affect both children and adults. You’ve probably seen people with poliosis in movies, on stage, or on TV. Johnny Depp’s character has it in the movie “Sweeney Todd.” Singer Bonnie Raitt has it naturally. The word for this condition comes from the Greek word “pilios,” which means “gray.” Melanin is the substance that gives hair its color. People with poliosis have a decreased level or complete lack of melanin in the roots of affected hairs, also called hair follicles. Poliosis alone can’t seriously harm your health, and it can be covered up with hair dyes, hats, or bandanas if you’re uncomfortable with it. But poliosis can sometimes co-occur with serious conditions. Signs of poliosis include one or more patches of white hair on hairy parts of the body. Poliosis often affects hair on the scalp, but can also affect the eyebrows, eyelashes, or other parts of the body that are covered with hair.