Blood under the toenail may mean injury
Did you drop something on your toe? Jam it into your door or bed? A bloody toenail is a common occurrence. It is easy to think, “Oh it’s just my toe, I’ll wait and see what happens.” Please don’t! Assess the injury, because there are instances where medical help should be sought quickly. One of these instances is a subungual hematoma, which is bleeding underneath your nail where it is trapped.
The tiny bones at the tips of your toes are very susceptible to fractures. However, it can often be hidden by the toenail. Having the space under your toenail fill with blood is common in injuries of this nature. This can often mask a visible fracture or other injuries underneath your nail such as nail bed trauma and lacerations.
A good rule is if more than 25% of the area of your nail has blood underneath, you should get medical attention. You should also seek care if the pain is bad or if it feels like pressure is building. The feeling is often a lingering throbbing that can be characterized as moderate to severe pain. When seeing your doctor, they will most likely need to drain the blood and evaluate the nail bed. X-rays are usually needed as well.
For all you runners out there, you may experience a recurrent bloody or black toenail. This is most likely because your shoes are too small/tight! The trauma to your nail is a minor repetitive jamming against your shoe. Going up a size or changing shoe types will often resolve the issue. Over time you will see the black part of your nail grow out. It may take awhile; your toenails take 9 months to completely grow out!