eli5: Fainting at the sight of blood. How does it work.

Question

Do people feel fear or disgust before fainting? And how much blood does it take to make someone faint? Is seeing someone with a nose bleed enough or do they need to see a lot more like a gallon?

In: 4

Answer 1

I never understood how some women would faint at the sight of blood…when they had periods every month.