Fungal infection: Onychomycosis, a fungal infection, can cause thick, brittle, and white or yellowish toenails.
Trauma or injury: Injury or trauma to the toenail can disrupt normal growth, resulting in white patches or streaks.
Nutritional deficiencies: Deficiencies in zinc, protein, or vitamin B12 can lead to pale or white toenails.
Allergic reaction: Some individuals may have an allergic reaction to nail products, causing white discoloration of the toenails.
Nail psoriasis: Psoriasis, a chronic skin condition, can affect the toenails, causing white spots or discoloration.