Fungal infection occurs when the organism invades through an opening in the nail, meaning fungi will usually attack nails that are already damaged. After infection occurs, the growth of the fungi leads to mild inflammation, which causes the nail to thicken and the nail plate to detach from the nail bed. The space underneath the nail can then serve as a reservoir for bacteria and moulds, which can cause the nail to become discoloured.
Infected nails are usually thicker than normal and could be warped or oddly shaped. They can break easily. Nails with fungus might look yellow. Sometimes a white dot shows up on the nail and then gets bigger. When fungus builds up under your nail, it can loosen and even separate the nail from the bed. The fungus can also spread to the skin around your nail.