If you suddenly discover that one of your toenails has turned black and hurts, you have most likely injured it.
Due to the fact that the blood vessels located under the plate are damaged, a black, dark blue or red hematoma appears.
As a result of traumatic damage to the nail, it may begin to peel off at the corners and fall off after a few days.

Of course, in such a situation it is worth seeking medical help - firstly, the doctor will cut the damaged nail correctly, and secondly, will recommend treatment for subsequent recovery.
If you notice that your nail has darkened, but there is no pain even when you press on it, check your shoes and socks: perhaps the nail plate has simply become discolored.
Doing a pedicure? Make sure that the reason for the blackening of the nail is not due to improper execution.
However, there are also much more serious reasons why toenails change color.
If, in addition to this symptom, you notice that you have begun to feel unwell and weak, you get tired more quickly, and your mouth is often dry, it’s time to check your body.
Such symptoms often accompany diabetes, kidney problems, or heart and vascular diseases.
If only one nail out of ten has turned black, be sure to exclude the possibility of a benign tumor - sometimes it can occur at its base.
The network of blood vessels grows, the plate becomes dark and may fall off, and the tumor grows and begins to interfere with walking.
The solution to the problem will be a simple operation, but your doctor will tell you more about this.