I know "designer drugs" primarily through psychedelic analogues (e.g. 1V-LSD); also, through psychedelic fakes (e.g. NBOMe in place of LSD), which can be fatal. I don't think either one of these are designed to avoid drug tests, but rather to avoid being technically illegal, so that they can be sold over the clearnet to average people. The fakes are designed to be cheaper to manufacture than the real thing, though not designed to be safe. People have died from overdoses of these analogues (and even from regular doses). You are not supposed to be able to overdose on LSD (at the very least, it should not be able to kill you), so this is pretty bad and unexpected when it happens. It's one of the major reasons why reagent testing is so encouraged by harm reduction communities: if you really want to take some substance, it's very important to make sure you know that you're taking the correct substance in the first place; otherwise, even what very limited bets you would've had are already off.
The reagent to test for LSD is usually Ehrlich's reagent, but many reagent kits come with multiple reagents so you can not only verify the presence of LSD but also the absence of other adulterants. One can never really be too safe; the wrong drug can have all sorts of undesired effects, all the way up to potential death (or Parkinson's as in the linked article).
The reagent to test for LSD is usually Ehrlich's reagent, but many reagent kits come with multiple reagents so you can not only verify the presence of LSD but also the absence of other adulterants. One can never really be too safe; the wrong drug can have all sorts of undesired effects, all the way up to potential death (or Parkinson's as in the linked article).
https://dancesafe.org