If bad = death or permanent worsening
Which of course can be the consequence of anything. Things that don't normally cause severe reactions. Things that don't normally cause
any reaction, until suddenly they do.
That's why responsible medical practitioners are so unwilling to experiment on patients, or to prescribe drugs for self experimentation. They know of cases where very low risk drugs caused death or devastating impairment, and the fact that it was so unlikely it couldn't have been foreseen doesn't help that person in the slightest. It doesn't remove the cost to society of their death or disability.
I'm still reluctant to accept that ME/CFS can be made a special case, one that's allowed to sit outside normal medical ethics.
I'm also still worried about the social ethics of encouraging experimentation on the public internet, where you can never be sure who's reading it.*
Yes, maybe we should be able to have spaces where grown adults can bat these things back and forth. There's a good argument for that, of course there is. But I keep pushing back because I can't help worrying that people may be persuaded that experimentation is reasonable, not because they understand the risks and ethical ramifications, but because they're inexperienced, or easily influenced, or are parents so desperate to help their sick child they'd willingly sacrifice a limb if they thought it would help.
So if I sound a bit arsy (which I do sometimes, I know!) that's why.
* I don't think using a members-only forum makes much practical difference in groups where the presumption is to approve people who ask to join, if it appears they have a genuine reason for being interested and agree to abide by the rules.
ETA: edited slightly to tidy up.