Jamaican vomiting sickness, also known as toxic hypoglycemic syndrome (THS),[1]acute ackee fruit intoxication,[2] or ackee poisoning,[1] is an acute illness caused by the toxins hypoglycin A and hypoglycin B, which are present in fruit of the ackee tree. Unripe arils contain concentrations of hypoglycin A that are 20-fold higher than those of ripe arils,[3] and can cause vomiting and even death. Some countries in the Caribbean and Western Africa experience frequent cases.[4]