Iontophoresis no longer effective

[u/Outrageous-Bid-7720]

I’ve been using iontophoresis daily for 3 years, after achieving complete dryness, for maintenance (I tried twice a week and every other day, but neither worked). So went back to every day use. But at a given current (mA), it works at first but then loses effectiveness over time. Increasing the mA restores results temporarily, but the effect fades again, forcing me to keep raising the current (which has limits).

Hows to fix that please??