[user68858788]

My best guess is that HPPD was triggered by how I used NyQuil as a young teen. I would drink half a bottle, sleep for half the day, and wake up feeling better. I did this pretty regularly for a few years whenever I got sick.

[Majora320]

NyQuil contains DXM which is a dissociative in high doses as well as having some seratonergic activity. I wouldn't be surprised if this was why, especially taking it with a still-developing brain.

[DontchaKnowit]

Dxm is the only thing that ever gave me hppd. Had fucked up night vision cause of all the visual snow for years after a few two-bottles-of-robitussin trips