Activated charcoal helps some of us with herxing as it can bind the toxins. But make sure to drink plenty of water . also take it at least 2 hours away from any other medicines/herbals.
It will bind to those and they wont work if you take it to close together.
Its important to have bowel movements after so your body gets rid of the binded toxins and it doesn't get reabsorbed back into your body.
For dosing I take Natures way and its says 280 mg per pill. I usually take 5 capsules.
For me it helps, I wouldn't say its instant relief but I notice it helps within 12 hrs to 18 hrs.
We are all different so hopefully others will chime in too.
Take care, Jo