What causes your pupils to be small on opiates?

Published July 15, 2010

Question by Winter: What causes your pupils to be small on opiates?
Also could someone tell me the reasons your pupils to dilate when on things like meth and ecstasy?

and please don’t answer “I don’t know”.

Best answer:

Answer by matthew h
I’m pretty sure meth doesn’t make your eyes dilate too much. But MDMA causes your eyes to dilate because of all the serotonin that’s being released. I don’t know the specifics, but the excess of serotonin causes your pupils to blow up to a huge size. It might have something to do with the eye wiggles as well (as in it’s caused by the pupil dilation).

I’ve honestly got no idea about the opiates, though. I’ve seen some insanely small pupils on someone on ketamine, as well, but no idea why.

What do you think? Answer below!