I concure on KI being a no-go for water purification, it is too stable a compound.

Also, for KI to really work, it already has to be in your system and replacing the normal form of iodine in your thyroid. And you can only take it for limited duration. The real trick is getting solid numbers for both- it seems to vary, 3-4 for pretreat and 15-30 days for negative effects, in the various materials I've read. It's better than nothing, but it's really only looking after you thyroid.

Eric, short of Rx items, what are you thinking for an antihistamine?