If someone wants to claim an approved medication is especially poisonous, the onus should be on them to provide evidence. Note that the great-great-grandparents 3 links are all individual case studies. One of them summarizes the situation: "overall, the frequency and severity of adverse events are rather low".
If one person experiences it in a trial of a group of, say, 60... That becomes a risk of 1.6% in the side effects profile.
Real world cases would be much, much, much lower to the point to where doctors in the ER wouldn't even know what they're looking at when it happens. Sometimes it gets diagnosed as a 'drug eruption' or an allergy, when it's more an immune hypersensitivity response.
I know anecdotal isn't what people want around here, but I had a reaction to Sulfa that was later diagnosed as Stevens Johnson Syndrome. The doctor who prescribed it to me never personally saw a case of it herself until I came along. Even then, she sent me to a dermatologist first.
https://www.webmd.com/drugs/2/drug-5530/bactrim-ds-oral/deta...
However, It's commonly listed at the top of the side effects list for this drug.
https://en.wikipedia.org/wiki/Stevens%E2%80%93Johnson_syndro...
Actual incidence of the syndrome?
> SJS is a rare condition, with a reported incidence of around 2.6[10] to 6.1[26] cases per million people per year. In the United States, about 300 new diagnoses are made each year. The condition is more common in adults than in children.
Up to 6 cases per million per year across ALL drugs and not just the one I mentioned here.
Even common over the counter medications like Ibuprofen is known to cause SJS. The odds, however, are vanishingly small.
The risk exists, yes, but the perspective needed is that when you see percentages reported... that's not a "1.5% chance", that is "1.5% of those in a particular group experienced this side effect while 98.5% did not."
This information is typically provided in the published drug facts for each medication.
https://pubmed.ncbi.nlm.nih.gov/2686432/
https://www.rxlist.com/cipro-drug.htm#dosage
Studies provide further info.
> or what doseage that occurs at or what causes this reaction in the subpopulation?
It's through trials they discover the incidence of side effects and appropriate dosages for maximum therapeutic benefit.
> You don't and just wave that off, that's why it's flippant.
Nobody is waving anything off when providing perspective.