Probably everyone's body is different. For many months every day I have taken a dropperful (actually about 3/4 full after one squeeze from the bottle) of Nature's Answer Wormwood /black walnut tincutre. No problems at all that I can tell.
However, when I took Wormwood tincture by itself, it did have side effects. Cramping, feeling a teeney weeney bit psycho. Short term. It is great for getting rid of Ascaris though, followed up by psyllium & Bentonite clay. It doesn't really necessarily kill the bugs, just stuns them so they can be moved on out.
Your body will let you know if you have too much and there are no long term side effects.