Fungal Nails
Fungal nail infections, also called onychomycosis, are common infections of the fingernails or toenails that can cause the nail to become discolored, thick, and more likely to crack and break. Toenails are much more commonly affected than fingernails.

Symptoms:
Thickened nails; Whitish to yellow-brown discoloration; Brittle, crumbly or ragged nails; Distorted nail shape; Dark color caused by debris buildup; Slightly foul odor; Separation of the nail from the nail bed (onycholysis)
Causes:
Fungal organisms like dermatophytes, yeasts, and molds; Warm, moist environments; Walking barefoot in public areas like pools or gyms; Diminished blood circulation; Weakened immune system; Diabetes; Aging (slower nail growth)
Treatments:
Oral antifungal medications; Topical antifungal nail creams and ointments; Medicated nail polish; Laser treatments; Nail removal in severe cases; Keeping feet clean and dry; Wearing breathable footwear; Using antifungal sprays or powders