The concern seems to be that giving milk thistle will slow down the body’s mechanism for getting rid of ivermectin. The body clears out about half of the ivermectin in the first 24 hours and in the next 24 hours, it clears about half of what is left and so on until it’s gone. The recommendation I read was to wait 3 days before starting milk thistle, so the ivermectin had a chance to mostly clear out of the system. On a normal healthy dog, after 3 days, there would be less than 1/8 of a dose left in the system.
