Cutting toenails incorrectly could lead to serious foot problems, chiefly ingrown toenails. Once a nail has started to grow incorrectly, it is very difficult to get it to grow correctly again.
Toenails should be cut using nail clippers. They should be cut straight across, and not in a half moon shape. If nails are difficult to cut, or have thickened, it is best to have them cut by a podiatrist, as incorrect cutting could cause future problems.
South African Podiatry Association (SAPA)