What causes horizontal nail ridges (beau's nails)?

Beau's lines: Some are infection in nail bed, injury, skin disease, low calcium, chemotherapy drugs.

Often no clear cause: If you do notice these ridges, don't assume you're ill. Point it out to your physician at your next routine checkup.

Need eval: Horizontal nail ridges (or Beau’s lines)run across nail & might be signs of diabetes, thyroid disease, kidney disease. They may occur in people who had syphilis or muscles or who had chemotherapy. These should be evaluated.