Brittle nails
This is a symptom of more severe levels of iron deficiency. The nails of iron-deficient people may become brittle and start to break and crack easily.
In more extreme cases, a condition is known as koilonychia or spoon nails [4] develops. This is characterized by thin, soft nails with a hollowness in the middle and turned-up edges. Spoon nails may occur in one or more of the fingernails. In rarer cases, it affects the toenails.
Koilonychia is a rare development that affects less than a fraction of people who suffer from iron deficiency.