Rosacea is a chronic skin disorder of the face in middle-aged and older people (usually between 30 and 60), which affects approximately 13 million people in the United States.

It tends to occur mostly on the face, and sometimes on the neck and upper chest. About 50 percent of the time it involves the eye area as well. It tends to occur more frequently in people with fair skin, and may be an inherited trait.

Doctors classify rosacea into four types depending on the symptoms. One of them is an...