What causes white nails?

Causes

By Mayo Clinic staff

Nail fungal infections are typically caused by a fungus that belongs to a group of fungi called dermatophytes. But yeasts and molds also can be responsible for nail fungal infections.

What are fungi?
Fungi are microscopic organisms that don't need sunlight to survive. Some fungi have beneficial uses, while others cause illness and infection.

All of these microscopic organisms:

Live in warm, moist environments, including swimming pools and showers
Can invade your skin through tiny visible or invisible cuts or through a small separation between your nail and nail bed
Cause problems only if your nails are continually exposed to warmth and moisture — conditions perfect for the growth and spread of fungi

Toenails vs. fingernails
Nail fungus occurs more in toenails than in fingernails.                                                                                    

Toenails often are confined in a dark, warm, moist environment inside your shoes — where fungi can thrive.

Diminished blood circulation to the toes as compared with the fingers makes it harder for your body's immune system to detect and eliminate the infection.