Medically reviewed by Katlein Franca, MD Nail psoriasis and onychomycosis (nail fungus) are both conditions that can discolor ...

Black toenails are usually the result of toenail injury. However, there are other things that can cause a black toenail, including fungal or bacterial infections. Most cases of black toenails aren ...

But sometimes, they can appear yellow, green, blue, purple, or black. Several things can cause toenail discoloration, also known as chromonychia, ranging from minor injuries to potentially serious ...