What could a horizontal red line under my big toenail signify?

The appearance of a horizontal red line under your toenail might be related to a condition known as 'half and half nails.' According to the medical literature, this condition can sometimes occur in healthy individuals. 'Half and half nails' are characterized by a distinct color change in the nail, where one part of the nail is a different color than the other. This condition is often associated with kidney issues, but it can also appear in people without any health problems.

In the specific case mentioned in the literature, a healthy person was observed with this nail condition without any underlying health concerns. It is important to note that while this condition can be seen in healthy individuals, if you are concerned about changes in your nails, it is a good idea to consult with a healthcare provider to rule out any potential health issues.