I have used garlic cloves in the water and often put organic unfiltered Apple Cider Vinegar in there, too. I do it for their immune systems, not worming, though. For natural worming, I use chopped pumpkin seeds and buttermilk. I have done chemical worming twice on my flock with Eprinex PourOn. There's no milk or meat withdrawal, so I would say it translates to no egg withdrawal, either, however, decide that for yourself.
EDITED TO ADD: I used chemical wormers only when I did see a worm in the poop of a rooster. We have so many flies and worms in the soil here and and other larvae, that I felt if I was seeing it in one, it was in more than I knew about. Other than actually seeing worms, I do not worm them at all with anything except natural preventatives. I agree on the antibiotics, too Rogue. Seems people run right to the Terramycin when they hear a bird sneeze.