Based on what Khaos had deciphered from the scriptures, hallucination was part of the side effect of the curses along with many more, it depended on the Shell's endurance.
But, all the Shell would be hallucinating at some point and when they reached this stage, it would be dangerous for them and all the people around her, because they could turn very violent, since they didn't recognize themselves or other people.
Hearing voices, creating stories in their head, feeling unsafe because they always thought someone might kill them and many more.
Based on the notes that was left behind, the last Shell managed to contain ninety eight curses, which left her with two more curses before it was completed, but her condition…. You could say that she was barely alive.
