No I have not seen much die off symptoms;
at the time I started Borax I had so much candida problems in my digestion system, so I couldnt tell what was die off or just a worsening of candida; sort of came in waves anyway.
At that time I took to many supplements, "type more is better" - made it more difficult to say what caused what.
The other people have only reported the typical Iodine reaction / detox ; as I always give both.
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Darker stools could simply be more red/dead blood cells.
Borax has some H2O2 (Hydrogen-Peroxid) effect, internally laundry LOL.