How do scientists figure out how chemicals affect the body? Surely it can't be an accident. As in "Hey, I accidentally sprinkled Dextromethorphan on my corn flakes this morning, and my cough went away!" or "I accidentally snorted some Phenylephrine last night, and my nasal congestion cleared up!" Maybe they're just good guessers, as in "I needed an antihistamine, and something told me that Doxylamine Succinate would do the trick!" Or maybe scientists are just playing tricks on each other all the time and sometimes they get lucky, as in "I spiked his coffee with some Guaifenesin as a goof, and it broke up his chest congestion... who knew?"
Of course, sometimes it probably doesn't go as planned, as in "I laced his chocolate pudding with Strychnine on a dare... it's not like I meant to kill him or anything."
I am entirely too bored laying in bed all day, obviously.