There are all kinds of side effect with both zappers & herbs, but I personally think they are both essential. However, I think Bob Beck was right that the bugs can hide out in the lymph nodes away from both. I could find no bugs whatsoever after using those two resources extensively for about 3 months. Then I tried the Sota Pulser, which he designed to get the critters in the lymph glads. It is pricey, but it seemed to Work. For a few nights I could hardly sleep due to itching and twitching (scatter I guess) and then it all stopped & I've had no problem such with maintenance pulsing.
I also found the Pulser took care of my carpal tunnel syndrrome, where nothing else helped much, so there's a side note.