Why do red eyes occur?

[make it legal]

i hate douchebags

yeah me too they suck

[Smokin EnDo]

MArijuana opens up your blood vessels and thus causing the dreded "fire eye" but that is the sole purpose it helps with glaucoma.

[exoticnoise]

i never usually cough when i smoke pot, and i always end up with red eye, i have heard of the blood vessels opening up tho, but i dont think its always from coughing.