Ketamine is just about the most vile and toxic substance you can put into your body next to inhalants and GBL. I have posted an article on here somewhere. Information is just emerging since chronic use is a relatively new phenomenom. I will try to dig up the article. Bottom line is: There is no organ that doesn't get wrecked by chronic exposure to ketamine.
A sterile shot of ketamine gave me a pretty nasty ulcer within a couple of hours since the concentration was too high. It can cause necrosis due to it's local vasoconstrictive effects. I also get nosebleeds a day after shooting it (or using other roa's for that matter).
It would be best to assume the same goes for all other dissociative arylcyclohexylamines.
one thing I have noticed, anecdotal evidence at best- ephenidine has some strange tax on the eyes. I think it either mild eye damage or some strange form of HPPD. I noticed that after taking it my eyes can kind of hurt. After using it fairly often for a few months, I've noticed that light burns into my eye easier, and looking away creates a more noticeable impression of light that wouldn't normally burn in. For example, If I'm in my bathroom and i weigh myself, the light from the scale will stay in my vision for longer than expected
Maybe it's just a combination of tense eye muscles and not blinking?
I took 50mg DPH once in the evening after having used EPE during the day, and the next morning I had this twitch in my right eye that just didn't go away. EPE seems to allow restless leg syndrome to crawl into your eyes so to speak.
The twitching stopped after some weed a week later.