By 'it' I'm assuming you're referring to Serotonin syndrome. In that case...Hello, iatrogenic caused Serotonin syndrome case sitting right here at your command.

(although if it's caused by a combination of an SSRI/SNRI and another serotonergic agent, and not by the SSRI/SNRI alone does that still make it iatrogenic? Hmm

) Anyway, long story short, ended up in Emergency, was originally admitted as urgent priority from memory, that very quickly shifted to a 'priority one emergency' (highest level, immediately life threatening) right about the time they started taking my vitals. You know when you're in the ED, and everything's kinda chugging along all nice and smooth, and then you actually see the patient's vital signs on the monitor and all of a sudden there's this 'okay, **** just got real' change of atmosphere that happens in the room? Yeah, it was like that. Scary, very unpleasant experience to begin with, and I don't remember things all that clearly by the time I was actually being treated (I was kind of spacing in and out a lot), except I do remember lines going in, and something about Valium, and fluids, and some other stuff being pushed through as well but I have no idea what that was. They did get me stabilised pretty quickly, and then I spent several hours (pretty much the rest of the day) under observation, before being released with a nifty little diagnosis and explanation of something called Serotonin syndrome (which up until then I had never even heard of). This was all before I was seeing my current Psychiatrist, so it was one of my previous GPs who decided that combining 75 mgs of Effexor with 300 mg of Tramadol was perfectly safe, except for me it ended up being a case of 'not so much'.
Having said all that I don't think I've ever met anybody else, that I know of, or can remember at least, who has experienced a legitimate episode of Serotonin syndrome, but I have plenty of overly anxious, emotionally disregulated friends who will cart themselves off to hospital in a complete panic at a moment's notice, because they've read about this thing called Serotonin syndrome and suddenly every bodily twitch, cramp, ache, or minor fluctuation in temperature is a potentially life threatening emergency. Not that I don't ever tell them *not* to go, because hello I'm not a Doctor but I can understand why claims or fears of Serotonin syndrome are sometimes met with skepticism by those in the medical profession.