It is common knowledge that [iodine] was used widely in hospitals for decades, and supposedly(?) resistance is not built up to it.
But iodine, and most iodine-containing medical preparations, are heavily restricted, due to the drug war.
Seems they're used in one step of turning pseudephedrine into meth. So, though they're not actually BANNED, the drug warriors put so much red tape on them that most chain-store drug stores just dropped them as unprofitable.
(I found this out when the fallout from Fukishima was approaching the US west coast, and I tried to find some iodine supplements for my family to dose up on, to reduce the risk from radioiodine, before it got here. Surprise! None to be had.)
If anybody knows of a chain store in California or Nevada where I can buy potassium iodide supplements or tincture of iodine, over the counter, please let me know.