★★★★☆
I took it for several years, initially I was much less affected by cold, and had less dry mouth and nose. Gradually my sleeping schedule cut down to 8 hours from 12. Yay!
A few years later I began getting bad colds regularly. After gradually cutting down and noticing an improvement, I quit the iodine; if I took 1/2 pill, within hours I had a stuffy runny nose.
At that point I figured I didn't need the iodine any more, I keep it in case I feel as bad as I did years ago and so far so good.
So: pay attention to your body, make small changes and if necessary keep a record of your progress.