The flavor text seems to imply, that they only help with physical damage, but the rules just say 'damage'.

Do Platelet Factories reduce both types of damage, physical and stun?

Bye
Thanee

Unless specifed otherwise, they do.

First Aid now works on stun, too.

I'd think so.

Seems to me that they rolled up SR3's trauma damper and platelet factory up inot one unit in SR4.

FirstAid is even explicit that it fixes Stun.

Although Platelet Factories doesn't explicitly mention Stun damage, the flavour text doesn't really discount Stun if you think of brusing as mostly Stun damage.

In the process of being beaten unconcious, you'll probably get some bleeding going on (although not necessarily the big, dramatic external kind). I don't have a problem with the platelet factories reducing stun damage, as the RAW implies that they do.

They would certainly reduce swelling around sprains and breaks, and I would think assist with things like nosebleeds, bloodclots, and anuerysm for the mages . . .