The Beau line can be a sign of malnutrition in a person's body, marked by a horizontal line along the nail. In addition, several other health conditions can also be the cause of the Beau on the nail line, including diseases that cause high fever such as measles and scarlet fever, peripheral vascular disease, pneumonia, uncontrolled diabetes, and deficiency of zinc minerals in the body .
In addition, the Beau line can also appear in patients who are or have been on chemotherapy treatments as well as patients who have Raynaud's disease while in an environment with very cold air. Abnormalities in the appearance of this Beau line can generally be eliminated. It takes about four to six months to remove this line on the fingers and six to 12 months on toenails.