Symbols of medicine

Rod of Asclepius vs caduceus: which is the symbol of medicine?

The rod of Asclepius is the symbol of medicine; the caduceus is the staff of Hermes, which American medicine took up in the 20th century. The National Museum of Civil War Medicine gives the difference in form: the rod has a single snake round a rough branch and no wings, and the caduceus has two snakes round a staff with two outstretched wings at the top. The American Medical Association says its own symbol has carried the single snake of the staff of Asclepius for nearly a century, that the rod has long been confused with the caduceus, and that in most mythology the caduceus is the wand of Hermes and often stands for commerce. The World Health Organization chose a staff with one snake for its emblem in 1948.

The disagreement is over whether the caduceus is a mistake. Stuart L. Tyson, in The Scientific Monthly in 1932, called it “an incontrovertible fact” that the wand with two serpents belongs to Hermes, not Asklepios, and put Hermes’ relationship to medicine at “tolerably near absolute zero”. Lee H. Schwamm, writing in the Journal of the American Heart Association in 2013, sees in the two emblems “this tension between the art of healing and the commercial realities within modern medicine”, and cites a 1990 survey of US organizations: professional associations more often used the rod (62%), commercial organizations the caduceus (76%). The Civil War medicine museum, choosing its own logo, concluded that either emblem would have been on “solid historical ground”, because hospital stewards and stretcher bearers in the Civil War wore the caduceus.

Asclepius and his snake

Pausanias describes the ivory and gold statue of Asclepius at Epidaurus: the god sits grasping a staff, his other hand held above the head of a serpent, a dog lying by his side. He calls the yellowish snakes of Epidaurus sacred to Asclepius and tame with people. Ovid’s Metamorphoses tells how the god came to Rome during a pestilence: in a dream he shows a Roman the serpent that entwines his staff and says he will be changed into it. Tyson dates the embassy to Epidaurus to 293 BC and the snake’s arrival to 291; Schwamm dates the Aesculapium on the Tiber island to 293 BC. A votive relief in the Acropolis Museum shows Asklepios leaning on his staff, a snake coiled round it. EMS.gov reads the skin-shedding snake as renewal. The WHO retells the legend that Zeus killed Asclepius with a thunderbolt after Hades complained of him, fearing he might make humans immortal.

The rod is on emergency and medical emblems today. EMS.gov says the staff and serpent at the centre of the Star of Life on American ambulances are the staff of Asclepius, and the MedicAlert Foundation puts the rod on its medical alert jewellery.

Hermes’ wand

In the Homeric Hymn to Hermes, the god is promised “a splendid staff of riches and wealth”, of gold with three branches, and given an office from Zeus to establish barter among men. In the Odyssey, Hermes uses his golden wand to lull men to sleep or wake them, and leads the spirits of the dead suitors with it. Smith’s Dictionary of Greek and Roman Antiquities (1875) calls the caduceus the staff carried by heralds and ambassadors in time of war, at first only an olive branch, whose decorations were afterwards formed into snakes, and records Hyginus’ tale that Mercury parted two fighting snakes with his wand, which made it an emblem of peace. Tyson calls Hermes the patron of commerce and the special protector of travelling salesmen.

How the caduceus came into medicine

Tyson names the mark of the Swiss printer Johann Froben as the earliest instance of the confusion, though he saw no reason to think Froben meant it for either god. ETH Zurich Library dates the mark to 1515 and reads its two snakes and dove as the verse from Matthew, “Be ye therefore wise as serpents, and harmless as doves.” John Caius, a physician, gave Gonville and Caius College, Cambridge, a silver caduceus in 1557. The college says its several snakes allude to Hermes, not Asclepius, and at the installation of a new Master in 2025 it was handed over as a symbol of prudent government. Friedlander’s history of the symbol, The Golden Wand of Medicine (1992), says in its publisher’s summary that an early 19th-century medical publisher took up the caduceus as the sign of a commercial deliverer of information; Tyson finds it in 1844 on the title pages of the London medical publisher Churchill.

Why the US Army adopted the caduceus

The Army is where the caduceus became a medical emblem in America, and the sources disagree on why it was chosen. William K. Emerson, in the Army Medical Department’s history newsletter in 2016, says hospital stewards wore it on their chevrons from 1851 to 1887, and the Army’s Institute of Heraldry quotes the 1851 regulation: “a caduceus embroidered in yellow silk on a half chevron of emerald green silk”. The National Museum of Civil War Medicine dates the stewards’ caduceus to 1856 instead, and says the Public Health Service took it as its symbol in 1871.

In 1902 the caduceus became the emblem of the Army’s medical officers. Emerson gives the reason of Colonel John Van Rensselaer Hoff, the medical member of that year’s uniform board: merchant ships in antiquity had flown the emblem of Mercury to show they were non-combatants, so the caduceus meant neutrality. Hoff ruled out the Geneva cross because it was also the emblem of Switzerland. The Civil War medicine museum says the caduceus is thought to have marked the corps as non-combatants, but that no explanation for the choice was ever given. The Institute of Heraldry reads it today as an emblem of physicians standing for knowledge, wisdom, promptness and medical skill. Friedlander, as his publisher summarises him, says the sign became widely recognized through its exposure in the First World War and, “once popular, bred popularity”. Schwamm also dates its spread as a medical symbol to the Army Medical Corps.

The bowl of Hygieia and pharmacy

Pausanias mentions figures of Health, “whom legend calls daughter of Asclepius”, and the Acropolis Museum’s relief shows her resting her right hand on her father’s shoulder. Gina Salapata of Massey University traces the image of a snake drinking from a vessel to the Bronze Age Mediterranean. She thinks it came to Hygieia through the double meaning of the Greek phármakon, a substance used both to help and to harm, and says the snake at her cup may be releasing its poison as medicine. Drug Topics, in its history of the Bowl of Hygeia award, records the stories that the bowl was an emblem of St John, or of the apothecaries of Italy in 1222, and says neither has been proved. The bowl’s first dated use for pharmacy, it says, is a coin of the Parisian Society of Pharmacy in 1796. APhA adopted it for the profession in 1964, and pharmacy bodies spell the goddess’s name Hygeia.