Why do hallucinogens cause the eyes to dilate?

Mydriasis also refers to the dilation of pupils, Basically whatever your body feels . . .It tells to your brain . .brain counter acts, So if you feel cold sensations by certain drugs,you start to shiver . . read more

The psychedelics, including LSD, magic mushrooms, mescaline, 2C-B, and DMT, to name a few, all do so by agonizing the serotonergic 5-HT2A receptors in the brain. How the neurological changes induced by these drugs ultimately causes pupil dilation is unknown however. read more

Dopamine cause pupils to dilate by exciting the adrenergic receptors, what in turn increases adrenaline (which the autonomic nervous system is sensitive to). It's important to remember that not all drugs will produce the same degree of pupil dilation. read more

Many hallucinogens induce mydriasis. The psychedelics, including LSD, magic mushrooms, mescaline, 2C-B, and DMT, to name a few, all do so by agonizing the serotonergic 5-HT2A receptors in the brain. The dissociatives such as ketamine, DXM, and PCP do so as well via antagonism of the NMDA glutamate receptors. read more