Nosebleed (epistaxis)

Epistaxis is the medical name for a nosebleed. It happens when a blood vessel, one of the tubes that carry blood around the body, breaks inside the nasal mucosa, the lining that covers the inside of your nose. It's about as common as it gets: roughly 60% of people have had one at some point.

Most of the time, the bleeding comes from the same spot. The inside of your nose is split down the middle by a wall called the septum, and at the front of that wall, right at the entrance, the branches of five different arteries come to an end. That meeting point is called Kiesselbach's plexus. Picture an intersection where five streets meet, out in the open with nothing overhead. The mucosa there is fragile and gets hit with everything: heat, cold, very dry air, and very humid air. A nosebleed from this front area is called anterior epistaxis.

There's another, less common type: posterior epistaxis. In this case the vessel that breaks isn't at that intersection near the entrance but at the back or the top of the nose, and this kind of bleeding is often hard to control. So what sets them apart is location: up front, at the fragile crossroads near the entrance, or at the back or the top, deep inside the nose.