Annatto is classified as E160(b) orange food color additive and is supposed to be safe if intake is up to 2.5 mg/kg body weight for annatto, and 0.065 mg/kg body weight for bixin. Side effects include allergies and eczema. It is not always known, however, which component in the mixture is the causative agent of the side effects. A subset of irritable bowel syndrome (IBS) patients may be also suffering adverse reactions to this food coloring additive.
According to recent findings, Bixin, a bright reddish orange compound found in annatto, may be valuable in the prevention and treatment of human skin cancers.