you can harm yourself with just about anything if you don't take appropriate care, yes.

Yes, be very careful not to accidentally dose yourself continuously during days-long sleep deprivation torture in a CIA mind control experiment. You might break something!

Actually, there's some literature on it being used to cure schizophrenia, autism, depression, mania, etc.

If you abuse it, or mix it with something else, you can hurt yourself for sure.

During the times in which they are illegal, there's a certain beauty to the rebellion of a person fed up enough with their unconscious misalignment that they break the rules and heal themselves. (as long as they don't get punished for it. if they're punished for it, the society becomes a degree crueler)

Of course, it would be a lot better if they were legal, but I don't particularly want to see a time in which the only way you can get access to these things is through system-mandated control.