I started drinking it yesterday, didn't cough at all last night, only a tiny bit today. Didn't wake up hacking like for the last few days. Coughed very early this morning for about 10 seconds, but other than that, I'm fine. I even went out into the dusty garage and moved boxes and didn't cough.
1/4 tsp borax and 2 drops of 5% Iodine to a liter of water, and no side effects so far.