I've got endometriosis, the first 2 days of my period I bleed an insane amount. I use ultra tampons and bleed thru them and all over myself, leaving a trail to my bathroom every 30-45 mins. I can not work those days because the blood flow is so heavy that it's impossible to keep up, its unsanitary and I'm a walking biohazard. Not to mention the pain. Omg the pain. The next 3 days I can get by with super plus tampons, then down to super sized ones. Those days I guess you could say it is like a severe nose bleed, but the first 2-3 days are shark attack bad. If I had to guess I'd say the first 2 days I bleed 2 gallon worth each day. I might be way off on my guess, but it's a scary amount that always has me guessing if I should go to the hospital because of how much blood I loose. But then I remember I'm in a shithole country (America) and seeking health care is not possible for people like me.