AFAIK, it only kills the bad guys. It’s extremely rare to have a reaction to iodine, but it does happen ocasionally. So you should test one drop in some water when you feel fine. If you don’t suddenly spasm and flop like a fish and then swell up and burst, you’re probably okay with it. :-)
Yes, I’ve read that iodine supplementation can be complicated ;-)
Probably something to get medical advice about, and read-up on carefully before using. Here’s the wiki, including a blurb on toxicity:
https://en.wikipedia.org/wiki/Lugol%27s_iodine
-JT