I apply to both wrists and inner arms where the skin is the
thinnest. It helps my carpal tunnel too that way. (where the veins show)

Skin on other body parts, is thicker, so I don't expect as much absorption as I get on the arms. I also use on the feet sometimes and my back if I need it there too.

Start weening off the HCTZ every other day, every 3rd day, then once a week.
I'd do it over a month or so.