SS is quite rare and it is seemingly dependent not only on a terribly unfortunate drug combo, but all the choices you've made in the past. Such as, how often you've rolled, smoked weed, done other drugs and so on. Slowly you become more susceptible to the syndrome.
To get SS you need to alter you serotonin levels to a point where your brain cannot handle all the excitement, this is done through serotonergic drugs being taken way too frequently or in combination with one another. For instance rolling too often, then taking 5-htp for multiple days in a row afterwards while smoking lots of weed can trigger SS. It would be even more likely that this would happened if you re-dosed on MDMA most of the the time and smoked weed like fucking 6 times a day for a couple of year prior to the incident (this is what happened to me). There are a lot more drug combos that can induce SS, but honestly, it is a rare happening. It's rare because the combinations of drugs needed to bring about SS are ones people often don't intend to take. When taking two powerful serotonergic drugs simultaneously, it is a very possible happening.... Although it's rare, anyone can get it really.. they just have to do all the wrong things. That's why is it so important to know what drugs you are taking and all possible contraindications.
Symptoms of SS would include heat flashes, a racing heart beat, high blood pressure (lasting for A LONG TIME) , fear of imminent death, paranoia, anxiety, muscle contractions, muscle twitches, audio and visual hallucinations, chills, shivers, nausea, diarrhea (when it comes to nausea and diarrhea you will realize that your bowels are paralyzed and you cannot do either but you really feel as if you have to), psychosis, bloating of the liver, kidney/intestinal bleeding (identifiable through blood in urine/stool), dizziness, lightheadedness, seeing black spots/feeling as if you are about to black out, seizures, coma, fever and death. Afterwards you'll experience HPB, possibly HPPD, severe emotional instability, unlock a predisposition to several mental disorders you never knew you had and some of the more psychological symptoms I just mentioned (stress, anxiety, paranoia, depression etc.).
As someone who is pretty sure that he got SS in the past I can tell you that if it is happening to you, you'll know something is terribly, terribly wrong.
