im pretty sure that red eye is caused by the smoke irretating your eyes(like how sand in your eye would make it red) thats why your eyes get way more red when your boxing it or something cause there is smoke all around you.

now for really really bloodshot eyes i dont think thats the case.
then for dry/cotton mouth that is because there is all kinds of smoke in your mouth it just drys it out.
and cotton mouth is caused by the dry mouth since you have no spit...