Board Thread:Dark Souls II/@comment-24679176-20140321161553/@comment-5264386-20140321211002

All Curse does in DaSII is essentially act as if you've died again, in that it reduces your maximum HP to the next tier. However, I'm not sure if it can reduce your health past 75%, but I know that it won't affect anyone wearing the Ring of Binding (found that out whilst being impaled on the Pursuer's Ultra Greatsword in the boss fight). In any case, all you have to do is pop a Human Effigy to restore your health to maximum.