Emperor Caligula is best known for his cruelty and eccentricities—the Roman emperor who allegedly promoted his horse to consul and murdered on a whim. But a new article announces a surprising element of the notorious emperor: his apparent familiarity with ancient medicine, in particular the use of hellebore, an active herb linked with the Greek city of Antikyra.

Caligula. Copenhagen, New Carlsberg Glyptotek. Credit: Sergey Sosnovskiy / CC BY-SA 2.0

In Proceedings of the European Academy of Sciences & Arts, Andrew J. Koh of Yale University and Trevor S. Luke of Florida State University return to a brief anecdote that the Roman historian Suetonius has left us. It entails a praetorian-ranked Roman senator who traveled to Antikyra to remedy an unspecified illness with hellebore, a plant applied in ancient times to treat epilepsy, melancholy, and mental illness. When the senator kept asking Caligula to give him an extension for his medical leave, the emperor ordered his execution, reputedly stating, “A bloodletting was necessary for one whom hellebore had not benefited in all that time.”

This sinister quip, hitherto understood to be a mark of Caligula’s sadism, can be seen to represent a nuanced awareness of medical practice in ancient Rome. According to the researchers, the remark actually reflects the language of medical texts of the period. It suggests that Caligula would have known the therapeutic duration of hellebore and even had knowledge of alternatives, such as bloodletting, promoted by Celsus in De Medicina, a treatise penned during the period of Caligula’s predecessor, Tiberius.

Researchers at the Yale Ancient Pharmacology Program (YAPP) combined ethnobotanical fieldwork in modern Greece with close reading of ancient materials like the Vienna Dioscorides manuscript. They discovered that while large quanтιтies of hellebore likely did not exist even in Antikyra, the town was renowned for its unique healing potions, most typically combining hellebore with another plant, sesamoides, to counteract its toxic effects. These potent potions helped build Antikyra’s reputation as a kind of “Mayo Clinic of the Roman world,” Koh explains.

Helleborus cyclophyllus in Dunedin Botanic Garden, Dunedin, New Zealand. Credit: Krzysztof Golik / CC BY-SA 4.0

Antikyra’s reputation as a healing center had already drawn Roman elites during the first century BCE. Caligula’s own great-great-grandfather, Marcus Livius Drusus, was treated successfully for epilepsy there in 91 BCE. The town was part of a growing trend in “ancient medical tourism,” in which affluent Romans traveled abroad for specialized care.

The researchers argue that Caligula’s ᴀssociation with Antikyra and hellebore was not coincidental. Ancient texts suggest the emperor suffered from insomnia, epilepsy, and mental illness—all conditions traditionally treated with hellebore. His paranoia may also have driven him to study poisons and antidotes: his father Germanicus died suspiciously, which the family believed involved poisoning. This climate of fear may have prompted Caligula to dabble in pharmacology—not just because he was interested, but because he needed to survive.

Marble bust of Caligula with traces of original paint beside a plaster replica trying to recreate the polychrome traditions of ancient sculpture. Credit: Ny Carlsberg Glyptotek, København

Caligula’s increased engagement with medical understanding is also supported by texts from the philosopher Philo of Alexandria, who, while a critic of Caligula, wrote that the emperor had extensive practical knowledge, including knowledge of medicine. Philo even accused Caligula of corrupting Apollo’s healing art for personal ends—a charge which ironically proves that he was familiar with those arts.

Although Suetonius and other ancient historians painted Caligula as a madman, Koh and Luke suggest that these portrayals may have deliberately twisted facts. The emperor’s interest in medicine, particularly his knowledge of hellebore and Roman pharmacology, could have been distorted into sinister narratives about mᴀss poisoning.

The researchers’ study does not aim to restore the overall image of Caligula but seeks to present a more complex image—one that recognizes the way medical knowledge was utilized, interpreted, and politically manipulated in antiquity.

More information: Yale UniversityPublication: Trevor S. Luke et al, (2025). Antikyran hellebore in the time of Caligula, Proceedings of the European Academy of Sciences and Arts. DOI: 10.4081/peasa.56