What does the snakehead nail mean?

It means that the nails are abnormal, which looks like a snake head.

Snakehead nails are abnormal, that is, the fingers near the nail end begin to be red, swollen and painful, and then develop into finger deformation, which is quite like snakehead. This condition is called gangrene in Chinese medicine. If not treated promptly and effectively, the second and third knuckles may be involved.