I have used various amounts of Lugol's 2% for a few years. Feeling under the weather a while back I put two droppers full (technically about half the dropper from a 2oz. bottle, twice) in a glass of water once or twice a day a few times, and when my next menses came it was only four days long, where previously it was always seven days. I used half a box of tampons rather than nearly the whole box.
My daughter's flow was very heavy...leaking through pads day and night...just awful and like this every month. She was starting to get scared to get her period each month. I started her on iodine tablets 12.5mg a day about 5 days before her period and for the first time the flow was normal and shorter. She continues with the iodine on and off for weeks until the week before then moves to daily. If she forgets to do this the heavy flow comes back.