The Rod of Asclepius ⚕︎
The true symbol of medicine is the Rod of Asclepius ⚕︎: a single snake wrapped around a plain staff. Asclepius was the Greek god of healing, and the snake, which sheds its skin, is usually read as a sign of renewal.
The rod appears in the logo of the World Health Organization and in the center of the blue Star of Life used by emergency medical services. Unicode calls ⚕︎ the staff of Aesculapius, the Latin spelling of the name.
Why people confuse ⚕︎ with the caduceus ☤
The caduceus ☤ has two snakes and a pair of wings. It is the staff of Hermes (Mercury to the Romans), the messenger god of trade, travel and thieves, so it has no traditional link to healing.
The mix-up became common in the United States after the medical department of the U.S. Army adopted the caduceus in 1902. Many American hospitals, pharmacies and nurse badges still use ☤, but medical organizations generally prefer ⚕︎. Unicode also includes ⚚, named the staff of Hermes.
Other medical signs and how to type ⚕︎
℞ is the prescription sign, from the Latin word "recipe", meaning "take". A green or red plus ✚ marks pharmacies and first aid in many countries, but the red cross itself is a protected emblem under the Geneva Conventions, not a general medical logo.
The health worker emoji 🧑⚕️ is a person joined to ⚕︎, so phones draw it as a doctor or nurse. To type ⚕︎ in Microsoft Word, enter 2695 and press Alt + X; in HTML, use ⚕. Nurses have their own page: nurse symbols. For the snake on its own, see the snake symbol.