Medical symbols: meanings, history and correct use

Medical symbols are images that stand for medicine, emergency care, pharmacy or humanitarian protection. Some come from Greek myth. Others were created by governments and international bodies since 1864. This guide explains what each symbol shows, where it came from and who is allowed to use it. It is part of our history of medicine section.

Medical symbols at a glance

Six common medical symbols differ in their shape, their meaning and who may use them. The table below compares them. This table covers widely used symbols only. It does not cover national, military or company logos.

Rod of Asclepius: one snake, one staff

The Rod of Asclepius is a single snake coiled around a plain staff, and it is the traditional symbol of medicine. Asclepius was the ancient Greek god of medicine. His rod with a single snake became a medical symbol from the fifth century BCE, according to the Wellcome Collection.

• The Rod of Asclepius has one snake and no wings.
• Internationally, it is the most popular symbol of medicine.
• The American Medical Association adopted the staff of Asclepius as its symbol in 1910.
• The WHO emblem and the Star of Life both use the Rod of Asclepius.

The snake’s shed skin was read as a sign of longevity and renewal, as a 2015 review in the Journal of Pharmacy and Bioallied Sciences explains. This section covers the symbol’s origin and meaning. It does not cover trademark rules for specific logos that include the rod.

Caduceus: two snakes, wings and the staff of Hermes

The caduceus is a winged staff with two snakes, and it belongs to Hermes, not to the god of medicine. Hermes was the Greek messenger god. The Romans called him Mercury.

• The caduceus has two snakes and a pair of wings at the top.
• In myth, the caduceus is linked with merchants, messengers and thieves.

The 2003 Annals of Internal Medicine paper by Wilcox and Whitham adds a surprise. The modern medical caduceus was drawn from the printer’s mark of a popular 19th century medical publisher. It was not copied directly from ancient art. This section covers the symbol’s history only. It does not judge any organization that uses it today.

Why the caduceus became common in the United States

The caduceus spread in the United States mainly because the US Army adopted it as its medical insignia in 1902. The Army Medical Department Center of History and Heritage gives the timeline.

• Army hospital stewards wore the caduceus on their chevrons from 1851 to 1887.
• In 1902, Army medical officers first began to use the caduceus as their emblem.
• Colonel John Van Rensselaer Hoff convinced the 1902 Uniform Board to choose it.
• Hoff linked the caduceus to ancient merchant ships and neutral status.

The 2015 review in the Journal of Pharmacy and Bioallied Sciences says the US Public Health Service and Marine Hospital also use the caduceus. It credits this largely to the Army’s 1902 choice.

Star of Life: the symbol of emergency medical services

The Star of Life is a blue six-barred star with the Rod of Asclepius in the center, and it marks emergency medical services. It was designed by Leo R. Schwartz, then chief of the EMS division at the National Highway Traffic Safety Administration (NHTSA). On February 1, 1977, NHTSA received a registration for the symbol as a certification mark, according to the Federal Register.

EMS.gov explains that each bar stands for one of six EMS functions:

1. Detection
2. Reporting
3. Response
4. On-scene care
5. Care in transit
6. Transfer to definitive care

You will see the Star of Life on ambulances, EMS uniforms and equipment. It tells you trained EMS responders are involved. It does not tell you what care you need. For basic steps before help arrives, see our first aid guide.

Red cross, red crescent and red crystal emblems

The red cross, red crescent and red crystal are protective emblems under international law, not general symbols of medicine. The International Committee of the Red Cross (ICRC) explains that they protect military medical services and relief workers in armed conflict.

• The red cross emblem came into being in 1864.
• Governments formally recognized the red crescent in 1929.
• Governments adopted the red crystal in 2005 as an extra protective sign.
• The red crystal has no national, political or religious meaning.
• A deliberate attack on anyone bearing a protective emblem is a war crime.

The emblems have two uses. Protective use marks medical staff, vehicles and buildings in war. Indicative use lets National Red Cross and Red Crescent Societies identify themselves. In the United States, federal law, 18 U.S.C. 706, limits the red cross to the American Red Cross and the medical services of the armed forces. The statute excludes uses that were already lawful before June 25, 1948.

The Rx symbol

The Rx symbol marks a prescription and comes from a Latin word. The Wellcome Collection says it derives from the Latin verb recipere, meaning “to take back” or “to receive.” It first appeared on doctors’ notes to chemists, the British word for pharmacists. Other origin stories circulate online. This page does not repeat them because we could not confirm them with a reliable source. Rx is a common abbreviation, not a legal mark or a license.

The WHO emblem

The WHO emblem is the United Nations symbol topped by a staff with one snake coiled around it. According to the World Health Organization, the First World Health Assembly chose it in 1948. WHO says the staff with the snake comes from the story of Asclepius. That makes it a Rod of Asclepius, not a caduceus. The emblem stands for WHO only. It is not a general health symbol, and WHO restricts who may use it.

Symbols are one way to judge who made a health message. Our guide to reading health information covers other clues to check.

Using medical symbols correctly

Several medical symbols are protected by law or restricted by the groups that own them. These points apply to US law and the named organizations’ own rules. They are not legal advice for your situation.

• Do not use the red cross emblem without authorization. The American Red Cross says the emblem is “not descriptive for medical or emergency care, first aid or disaster response.”
• For first aid, the American Red Cross suggests a white cross on a green background instead.
• Do not tilt, recolor or build the red cross into a logo. The American Red Cross lists these as misuses.
• Ask NHTSA before using the Star of Life. EMS.gov directs requests to its Public Affairs office.
• Use the WHO emblem only with express written permission from WHO.
• For a general medicine symbol, choose the Rod of Asclepius. Its single snake matches the ancient symbol of medicine.