10 Facts About Mithradates VI, the “Poison King” of Ancient Pontus

Mithradates VI Eupator (the last word means “of noble father”) was a Renaissance man 1500 years before the Renaissance. Born in 135 BCE, he ruled as the king of Pontus, a small province on the edge of the Black Sea in what is now northern Turkey. He is also known as the “poison king”—though not just because he poisoned his friends and enemies—as well as an early toxicologist, military leader, and hero. Here are the facts about this legendary king. 

1. Classical historians believed his greatness was signaled by a comet.
2. Mithradates’s father was poisoned in a palace coup.
3. Mithradates VI survived poisonings himself.
4. He practiced an early form of immunization.
5. He was a polyglot.
6. He really hated the Romans. 
7. Mithradates VI launched a secret plot to force the Romans out of Asia.
8. He tried to end his life with poison—but it didn’t work.
9. He inspired works by Mozart and other artists.
10. Mithradates VI also inspired modern medical terms.

Classical historians believed his greatness was signaled by a comet.

The Roman historian Justinus, relaying a story from an earlier philosopher, wrote in 37 BCE that a comet had appeared in the year of Mithradates’ birth: “The future greatness of this prince even signs from heaven had foretold; for in the year in which he was born, as well as in that in which he began to reign, a comet blazed forth with such a splendor, for 70 successive days on each occasion that the whole sky seemed to be on fire. It covered a fourth part of the firmament with its train and obscured the light of the sun with its effulgence; and in rising and setting it took up the space of four hours.” The historian Seneca also described a comet occurring around the time Mithradates VI was born.

As king, Mithradates VI minted small-denomination coins depicting a comet on one side and Pegasus on the other as a reminder of his destiny that would circulate among his subjects.

Mithradates’s father was poisoned in a palace coup.

In antiquity, poison was routinely used to dispatch inconvenient royals and their families. When Mithradates VI was 14 years old, his father Mithradates V was poisoned at a banquet. The murdered monarch left his kingdom in the hands of his wife, Queen Laodice, and their two oldest sons Mithradates VI and Mithradates Chrestus. Neither was old enough to rule, so Laodice became the regent (giving rise to the idea that she may have been complicit in the coup). 

Mithradates VI survived poisonings himself.

After inheriting the kingdom, Mithradates VI survived a poisoning attempt (likely staged by his mother) and fled to a mountainous wilderness with a group of friends. He stayed there for several years, learning about plants and hunting and becoming self-reliant, Adrienne Mayor writes in The Poison King: The Life and Legend of Mithradates, Rome's Deadliest Enemy. 

Upon his return to Pontus, which was likely welcomed by those who remained loyal to his father, Mithradates VI had his mother Laodice imprisoned, murdered his younger brother Mithradates Chrestus, married his 16-year-old sister (who would eventually plot against him), and began to expand his kingdom. 

He practiced an early form of immunization.

Mithradates VI is called the “Poison King” because of his obsession with finding a universal antidote to all poisons—self-preservation for a young king. Historians believe he ingested small amounts of poisons regularly to immunize himself against them, a sort of ancient vaccine. The concoctions contained between four and 54 ingredients, with honey as a mixer, that would supposedly nullify any poison someone might slip him. He tried them out on condemned prisoners. 

He was a polyglot.

According to Pliny the Elder, Mithradates VI spoke the languages of the 22 regions he ruled “and could harangue each of them, without employing an interpreter.”

He really hated the Romans. 

The Roman Republic was at its full strength as a world superpower during his reign. Mithradates VI, descended from and allied with Greek and Persian dynasties, detested the Roman Republic’s expansion attempts into Asia Minor. When a Roman commander went rogue and invaded Pontus, Mithradates’s troops not only defeated them but kept going, launching the Mithradatic Wars to beat back Roman encroachment into Pontus and other areas of Asia Minor. The first of the three wars erupted in 89 BCE and set the stage for an anti-Roman massacre the following year.

Mithradates VI launched a secret plot to force the Romans out of Asia.

In 88 BCE Mithradates communicated tacitly with the former leaders of Rome’s newly acquired Asian provinces. He presented a simple proposal: encourage all their citizens forced under Roman occupation across these lands to slaughter every Roman or Italian person—man, woman or child—on an appointed day. Adrienne Mayor in The Poison King estimates 80,000 people or more were killed, leaving the instigator of the bloodbath as the sole ruler of Asia Minor.

“How Mithradates kept the plot secret remains one of the great intelligence mysteries of antiquity,” Mayor writes. Scholars still debate how Mithradates VI organized ordinary people, rich, poor, and enslaved, to commit genocide in response to the harsh rule of the Romans.

He tried to end his life with poison—but it didn’t work.

Fighting between armies went on and political boundaries continued to shift during the second and third Mithradatic wars. A huge army under the Roman general Gnaeus Pompeius, known as Pompey, attacked Mithradates’s troops and inflicted major casualties, finally defeating the Pontic king in 63 BCE. While Pompey took over Asia Minor, Mithradates fled to Crimea and began rallying his army for a defense of that territory against Pompey’s navy. However, unrest within the Crimean forces allowed Mithradates’s son, Pharnaces, to stage a coup against his father. 

Pharnaces gave Mithradates the choice of taking his own life or being killed. Though the exact circumstances are murky, legend suggests that he attempted to poison himself, but his lifetime of microdosing had made him immune to the toxin {PDF}. Allegedly, his bodyguard had to finish him off. 

He inspired works by Mozart and other artists.

French playwright Jean Racine’s Mithradates, a tragedy that plays loose with historical facts and focuses on love and betrayal in the Mithradatic court, premiered in 1673. It served as the basis for Wolfgang Amadeus Mozart’s first Italian-style opera, Mitridate, Re di Ponto, which he composed in 1770 when he was only 14.

Mithradates VI also inspired modern medical terms.

Mithradates VI’s experiments with poisons is recalled in more recent medical terminology. During the Renaissance, physicians used antidotes called mithridatum against the plague, writes Duane W. Roller in Empire of the Black Sea: The Rise and Fall of the Mithridatic World. By the early 16th century, a concoction of herbs meant as an antidote to poison or disease was called a mithridate. Even today, the practice of dosing oneself with increasing amounts of a poison to build tolerance against its effects is described as mithridatism.

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