The cause of itching in fingernail fungus is likely due to trapped moisture, according to Nail Doctors. The fungus survives in warm, moist environments that enable them to multiply, which causes the itching.
Fungus is a cause of onychomycosis, a nail infection which spreads through direct contact with the fungus, explains Mount Sinai Hospital. It is not as common for fungus to attack fingernails as it is to find fungus on toenails. Wearing nail polish or acrylic nails are some of the possible ways that this can occur. Exposing the hands to water often, such as when cooking or washing, can also open nails up to infection, notes Patient.