Just how much poison damage do they do?

[Archon_Wing]

Every time I have to fight them in the course of time since I started Diablo, I bang my head against the wall because their poison damage drains my life like mad even with poison resist. I've even tried to turn cleansing on, but it's still quite annoying. Perhaps more annoying is running back to town when your merc dies of poison. So is it just necessary to pack more antidotes vs them?:o