The only side effects that I have experienced from Iodine supplementation, (apart from the initial detox), was feeling well, increased immunity, no FBD, increased energy, better eyesight and so many more. As Trapper has often said, Iodine makes everything work better.
It seems that everyone who begins Iodine supplementation goes through some sort of detox, to a greater or lesser degree, it seems to vary from person to person. If you put the word detox into the search box at the top of the page, it will give you tons of info on this, also reading the FAQ at the top of the page, has helped a great many people with knowledge about iodine to begin with.