These two symbols have very different meanings! When referring to medicine, use the rod with one snake, called the Rod of Asclepius! For commerce (and some other things, see below) use the winged staff with two snakes, called the Caduceus!
The Rod of Asclepius (displayed to the left) is the symbol for the ancient Greek god Asclepius, known as a god of medicine. It is a rod with one snake. The symbol is used today as a symbol for the medical profession. You can commonly find this symbol on ambulances and… everywhere a medical symbol is needed.
The Caduceus (displayed to the right) is the symbol for the ancient Greek god Hermes. It is a staff with two snakes and wings. Hermes is known for being a messenger of the gods, guide to the dead, and protector of merchants, shepherds, gamblers, liars, and thieves. The Caduceus is generally used today as a symbol of commerce.
Why is there confusion in the U.S.?
In 1902 the US Army Medical Corp chose the Caduceus as their insignia. Most scholars regard this as a flat-out mistake. The US Army writes that the Caduceus represents “the non-combatant status of military medicine on the battlefield”. The Encyclopedia Britannica notes, “Among the ancient Greeks and Romans [the Caduceus] became the badge of heralds and ambassadors, signifying their inviolability.” So maybe the US Army was thinking the symbol would convey a sense of “… Hey, hey, hey, don’t kill me, I’m just a messenger delivering the wounded to the hospital!” or some such. That feels like a stretch to me. Today, military ambulances use the red cross and and civilian ambulances use the Star of Life, which prominently features, you guessed it, the Rod of Asclepius.
So why shouldn’t a medical provider use the Caduceus? Let me count the ways! Being the symbol of Hermes, it may imply the medical provider will kill you (guide to the dead!), sell your organs (protector of merchants!), feed your body to the dogs (shepherds!), hock your jewelry (gamblers!), and tell your mom they haven’t seen you in a week (liars and thieves!). So it’s not so much of a reassuring symbol! If you are a medical provider, please be sure you are using the correct symbol!
There are many articles where historians and professionals delve into this issue. Almost all of them say the US Medical Corps are definitely using the wrong symbol. Here’s a few to get you started:
- Finn, R., Orlans,D. A., Davenport, G. (1999). A much misunderstood caduceus and the case for an aesculapion. The Lancet, 353 (9168), 1978. http://dx.doi.org/10.1016/S0140-6736(05)77199-3
- Wilcox, R. A., & Whitham, E. M. (2003). The Symbol of Modern Medicine: Why One Snake Is More Than Two. Annals Of Internal Medicine, 138(8), 673. http://www.ncbi.nlm.nih.gov/pubmed/12693891
- Things you don’t learn in medical school: Caduceus http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4439707/
- Wikipedia has a trove of well referenced info about the subject: Caduceus as a symbol of medicine, Caduceus, Rod of Asclepius, pictures of Ambulances,
- Realizing the mistake, Monmouth University Nursing School removes the Caduceus from their logo in 2018
Here is the full text from the US Army Medical Department Office of Medical History Frequently Asked Questions page, retrieved 10-31-20. (bold is mine)
Why does the Army Medical Department use the Caduceus, which represents the Greek god Hermes and the Roman god Mercury, instead of the Staff of Asclepius, the Greek god of healing?
The Army Medical Department uses both the Caduceus (Mercury’s/Hermes’ Staff) and the Staff of Asclepius as symbols for the Army Medical Department (AMEDD). The Staff of Asclepius, or Aesculapius, symbolizes the medical mission of the AMEDD, and is included on the AMEDD Regimental Crest (the staff with one snake entwined around it). The Caduceus, two snakes around a winged staff, symbolizes the non-combatant role of the AMEDD. The Caduceus was first used on enlisted men’s uniforms in 1851, over a decade before the establishment of the Red Cross as a symbol of non-combatants. In 1902 the Caduceus was chosen to replace the Maltese Cross insignia on Medical Corps officers’ collars. In 1907, the Army Nurse Corps – the only other officer corps in the AMEDD at that time – began wearing a Caduceus with the letters ANC superimposed over it. Since that time, all new officer corps have been represented by a Caduceus specific to their corps, worn on the collars of their officers. After the First World War, many medical professionals left the army and returned to civilian practice. When they did, they took with them the Caducei they had worn proudly as members of the Army Medical Department. Over time, the Caduceus became associated with medicine in America, even in medical practices that had no association with the Army. Originally, though, the Caduceus did not stand for medicine, but represented the non-combatant status of military medicine on the battlefield.
Also notable iconography:
The Bowl of Hygieia is an important symbol of pharmacy and medicine. It is associated with Hygieia, the god of health. And, yes, the symbol looks similar to Asclepius’s rod!