I've commented on this before. Reddit seems to love it but I think it's probably useless/hazardous. And I'm a doctor so that should count for something.

Look, the problem with a gunshot wound (GSW) is not necessarily that there's blood, it's that there's bleeding. Subtle difference, but follow me: If you sever a large artery, say... the femoral in your leg. You bleed, right? Like, a lot. All this thing is doing is sopping up the blood that has already bled, not actually stopping the bleeding.... I don't care about blood that's already out. I want to stop the blood from coming out. For that, you need to apply direct pressure, elevate, pressure on the artery more closely to the body, clamping the artery/tourniquet and ultimately, surgical closure.

Shoving a bunch of tampon bits in the wound really would do nothing to stop major bleeding, it really just makes the surgeon's job that much harder because now he has to try and find all these gooey bits that are stuck in the wound. If he/she misses one... well now you've got a raging infection on top of your gun shot wound.

Even so, let's just say that it DOES stop major bleeding. But with the increased likelihood of infection, you have to look at overall mortality. Sure, you might survive to the hospital, but die from the ensuing infection. At that point, it's pretty much a wash. Either way you die, but the infection is a much more miserable way to go. I'd like to see the numbers because I doubt they could make the case that there's actually an overall mortality benefit.

You know what else stops major bleeding that actually has proven mortality benefits? Tourniquets. This stupid thing is an expensive way to distract medics from solid, time-tested ways of saving lives.

Ok, so not for major bleeding. How about minor bleeding? Ok, so... minor bleeding isn't life threatening, by definition, right? So why would you go and introduce an infection risk into the wound for bleeding that isn't going to kill you? Again, throw a dressing over it to keep dirt out, elevate, direct pressure, pressure on proximal part of the artery.

Plus... GSW is kind of non-specific, isn't it? I wonder how many people, in the heat of the moment, try to inject this crap into a head wound and cause a brain herniation. Or into the abdomen where it will do no good whatsoever. I imagine a minor liver laceration, some well-meaning medic injects this stuff and ruptures the liver... someone who would've lived now dies because their liver got exploded into pieces.

I think this thing is junk and a hazard. It sounds good on the surface, but if you actually think about it there's nothing it's good for.