There are three poisonous Aloe species – Aloe ballyi, Aloe elata and Aloe ruspoliana. These species have leaf sap that gives off a strong ratty odour. Fortunately the first two species are relatively rare and not widespread but it is important to know your aloes before attempting to use them medicinally.
Hepatotoxicity from aloe vera is rare and cases have been self-limiting upon stopping the herbal. While some reported cases have been severe or prolonged, there have been no instances leading to fatalities, liver transplantation, chronic hepatitis, or vanishing bile duct syndrome.