There's a bit of a learning curve in that dungeon for a new healer. If the rest of the group isn't playing up to par it is going to be a bad experience. Typically you wouldn't ask the other members to bring potions or antidotes as dealing with removing the poisons and reactive healing shouldn't be too much to handle. It just might be busier work than you have had in the past dungeons. Even for experiences healers if the other 3 members aren't respecting mechanics and dodging, it's easy to overwhelmed in some of those fights.