I use Iodine in my shampoo and also in the conditioner.
I mix saturated borax water (one heaped tablespoon to one quart warm water) 50-50 with my regular shampoo and add about 10 drops of Iodine per 4 oz
My hair loves this.

I use Iodine on my scalp when I get a pimple in my hair and it turns my white hair bright yellow for at least a day.

I mix a full dropper of Iosol Iodine in my shampoo and rinse. The shampoo and rinse are very diluted with a bit of borax mixed in as well in the shampoo. Makes my head not so itchy anymore and I seem to be losing less hair than usual.

nj