[Ria P]

I use Kaytee too but also use woodshavings in the play pen and transport boxes. Never had any issues.
I'd put the woodshavings into a digging box or tray then see what happens. Easily removed shoud they cause an allergic reaction which i don't think is that likely.
Two of my hamsters have connected cages, one with Kaytee and one with woodshavings plus a little Kaytee in heaps.
They use both and sometimes chose to dig and sleep in the woodshavings.

I wouldn't sleep in a bed with fleas that makes me itch or sneeze......