Onychomycosis refers to a fungal infection of the nail plate, nail bed, or both, caused by dermatophytes, yeasts, or non-dermatophyte molds.
It is a chronic, progressive infection that leads to discoloration, thickening, brittleness, and nail separation from the nail bed.
While not immediately dangerous, it can cause pain, secondary bacterial infections, and psychosocial distress, and spread to other toes.