Many changes in fingernails or toenails may cause people to think they have a fungal infection of the nails, medically known as onychomycosis or tinea unguium.
Fungal infection of the nails sometimes makes the condition sound contagious or related to poor hygiene. In fact, up to 10% of all adults in Western countries have fungal infection of the nails. This percentage increases to 20% of adults who are age 60 or older. Toenail fungus is much more common than fingernail fungus.
In reality, abnormal-looking nails may be caused by a number of conditions including, but not limited to, fungal infection. There are many other reasons why your nails may look different.