Hello, I can share my experience about this as I 'regularly' consume small amounts of SN (I do this to fool doctors to give me medication that I need to ctb, benzo, antiemetics also morphine sulfate, all covered by insurance). SN is terribly easy to get in my country, sold as indigosol fabric dye at dirt cheap price. To my experience, SN gives off 'bleach like' smell, it's pretty strong. Same goes for the taste and it's not that bad actually. All I did usually was mix around one spoonful of SN with idk, half a water bottle (that holds 300ml capacity). I would take a sip or two of this concoction in the hospital while waiting for my doctor's appointment (neurologist) and would faint in fifteen minutes to twenty minutes. They would just take me to the ER and found nothing wrong with me from bloodwork, ekg, etc, aside from my oxygen level being low. I just complained to my neurologist about terrible headaches everytime and they gave me medication that I need: odansentron (because I kept complaining about vomiting and losing weight, in truth I've been starving myself), propranolol (for the racing heartbeat), alprazolam (because I've been complaining of being unable to sleep) and morphine sulfate (for the severe headache). My neurologist trusts me enough because I've fainted repeatedly during our appointment, things like that can't be easily faked, I guess.
The thing is, I've been using the same concoction for about three months now and it's still working wonder as long as I fasted a day before my usual doctor's appointment. So no need to worry about SN purity degrading at all.
As the pain, it's not bad at all. Just dizziness, vomiting and the obvious feeling of losing consciousness, I guess. Also, I can breathe just fine, no feeling of choking, etc. If I take one or two sips, I'll usually feel sleepy (this is without taking anything like benzo, etc) for the rest of the day and I'll wake up feeling fine. Human body is so resilient, unfortunately. Take this information as you will. Also, excuse my English.