Poison is (mostly) a temporary effect, and can be countered by your own regeneration (innate or healing auras on jewelry), a healing spell or health / rejuvenation potions.
With the temple in the bandit camp, there is a trail you can follow to avoid the poisoned areas.
I don't know why the character complains so much about being poisoned, even when it isn't doing noticeable damage, or comes out with the 'must find a cure' line.
