What is a common cause of Beau's Lines in nails?

Beau's Lines are transverse grooves or indentations that develop on the surface of the nails and indicate a period of physiological disruption that has affected nail growth. A common cause of Beau's Lines is systematic illness. This typically refers to conditions that affect the entire body rather than localized issues, resulting in a temporary slowing or cessation of nail growth.

When the body is under significant stress due to illness, such as a severe infection, high fever, or other systemic health issues, this can hinder the ability of the nail matrix to produce nail cells effectively, leading to the formation of these lines as the nail grows out. Beau's Lines will often appear after the body recovers from such an illness, reflecting the interruption in growth that occurred during that time. The identification of these lines can therefore serve as a visual indicator of past systemic health concerns.