Fungal infections of the toenails, also known as onychomycosis, are a common condition that can cause thickened, discolored, brittle, or crumbling nails. Nail fungus develops when fungi enter the nail through small cracks in the nail or surrounding skin. Warm, moist environments such as sweaty shoes, locker rooms, and pools increase the risk of infection.

While toenail fungus is not usually painful in its early stages, it can worsen over time and lead to discomfort, nail deformity, and difficulty walking if left untreated. Early diagnosis and treatment can help improve nail health and prevent the infection from spreading.

Fungal infections can also affect the skin of the feet, commonly known as athlete’s foot, and may spread to the toenails if not treated.