A small change in a fingernail or toenail can be easy to dismiss. After cutting a nail, however, some people notice tenderness, swelling, pressure, or a dark red, purple, or black area beneath the nail. In some cases, this can happen because the nail or the delicate tissue underneath it has been accidentally traumatized.
One possible result is called a subungual hematoma — a collection of blood beneath the nail. It can occur after direct pressure or a minor injury to the nail, and the affected area may become painful and
How Can Cutting a Nail Cause a Problem?
Cutting the nail itself normally should not cause swelling underneath it. The problem can occur if the nail is accidentally injured while being trimmed — for example, by applying excessive pressure, cutting extremely close to the skin, or catching the tissue underneath the nail.
The nail sits directly over the nail bed,
a sensitive layer of tissue containing small blood vessels. Trauma to this area can cause some of those vessels to bleed, allowing blood to collect beneath the nail. Because there
