Examination of a patient’s nails can provide clues about his or her general health or specifically about the status of his or her skin. Many skin conditions can affect a person’s nails, including psoriasis, eczema or alopecia. When someone has had a recent illness, the nails can change in their growth or shape. Other conditions affecting nails can include infections and allergic reactions. Dermatologists are trained to use clues gathered in the examination of a patient’s nails to determine the cause of the changes and the most appropriate treatment.