Wormwood (artemisia absinthium): should be taken in small quantities and not over extended periods of time. e.g. they mention no more than a few tea cups per day. I use only a pinch or two and so far 3-4 times a week for just a few weeks. In excess, wormwood can cause diziness, nausea, vomitting, headaches,...
Rosemary: should also be taken in small (homeopathic) quantities, no more than a few tea cups per day. Leaves should not be eaten in large quantities. Actually Rosemary is more dangerous than wormwood, as the PDR writes that eating large quantities of Rosemary will cause vomitting, internal (stomach?) bleeding, etc... and eventually can cause DEATH!
Mugwort: I did not find any side effects for that one. But I'll check again next time.
All these should always be taken in "homeopatic" quantities, that is, for example, enough to make a cup of tea (not eaten in salad as a main dish!). And also all these herbs should not be taken by PREGNANT WOMEN. Rosemary is even sometimes believed to induce abortion!!!!