Bad trips are not the result of indigestion, malevolent spirits, wrong dosage, or infelicitous set or setting. They are the result of personality disorders. As it says in the Theologica Germanica, “nothing burns in hell but self-will”.
Unless and until you burn away all trace of self-will, you will suffer mental and emotional distress, confusion, anxiety, paranoia, disturbing imagery, negative thought loops, nausea and physical discomfort. Plant medicines hold up a mirror to your ego, and an ugly ego is a frightful and fearful thing.
Beware of your ego. You will suffer in your own personal hell if you are a grandiose or covert narcissist; you will suffer if you are a sadist; you will suffer if you are borderline, dependent or obsessive-compulsive. There is always the possibility of redemption and healing, but the only way out is through: you must suffer into truth.
“And in this bringing back and healing, I can, or may, or shall do nothing of myself, but just simply yield to God, so that He alone may do all things in me and work, and I may suffer him and all his work and divine will. And because I will not do so, but I count myself to be my own, and say ‘I’, ‘Mine’, ‘Me’, and the like, God is hindered, so that he cannot do his work in me alone and without hindrance; for this cause my fall and my going astray remain unhealed. Behold! This all cometh of my claiming somewhat of my own.”