Green Pots in Rachel are invaluable (esp. if you're a mage, you'll get owned without them).
And the HP draining function of poison is not the best bit. It's the 25% decrease in the enemies' defense. This could turn a 10k Sonic Blow into a 12.5k Sonic Blow, or such. Poison is still very good and very worth curing ASAP, in my opinion. It's just tough to use in a meaningful manner.
