Why are my toenails yellow?

Yellow toenails can be caused by wearing toenail polish for an extended period of time, a vitamin deficiency, or fungus starting to infiltrate your toenails. The best way to figure out why your toenails are yellow is to have a toenail biopsy. It doesn't hurt! Your doctor takes a small clipping of the tonail and sends it for a PAS stain. This simple test will narrow down the causes of your yellow toenail and tell us if you have a fungal infection. Don't delay finding out the cause of your yellow toenails since fungus can spread rather rapidly!