They are the same substance. Epinephrine is the international non-proprietary name used in medicine and in the United States; adrenaline is the British Approved Name and the common word almost everywhere else. The split is naming politics, not chemistry.
The core difference
There is no chemical difference. One molecule, two names, divided largely by geography and by a trademark dispute over a century old.
- epinephrine — the International Non-proprietary Name, standard in US medical use.
- adrenaline — the British Approved Name, and the ordinary English word.
Why there are two names
Both were coined around 1900 from the same idea: the hormone comes from the glands above the kidneys. Adrenaline is Latin — ad renes, at the kidneys. Epinephrine is Greek — epi nephros, upon the kidney. Same meaning, different classical source.
Adrenalin was registered as a trademark in the United States, which pushed American scientific and medical writing towards epinephrine as the generic term. Britain kept adrenaline. The divergence then hardened into two official naming systems.
Where each is used today
In the UK, medicine and the public both say adrenaline, and product labelling now often prints both. In the US, clinical usage is epinephrine while everyday speech is adrenaline — an adrenaline rush, adrenaline junkie. Nobody says epinephrine junkie.
What it actually does
Released from the adrenal medulla under stress, it raises heart rate and blood pressure, opens the airways, and shifts blood towards muscle. This is the fight-or-flight response. Clinically it is the first-line treatment for anaphylaxis, which is why auto-injectors carry it.
Noradrenaline and norepinephrine
The same split repeats for the closely related hormone: noradrenaline in British use, norepinephrine in American. Again one substance, two names.
Frequently asked questions
Is epinephrine the same as adrenaline?
Yes, exactly the same substance. Epinephrine is the standard name in US medicine, adrenaline in the UK and in ordinary English everywhere.
Why does it have two names?
Both were coined around 1900, one from Latin and one from Greek, and a US trademark on the name Adrenalin pushed American medical writing towards epinephrine.
Is noradrenaline the same as norepinephrine?
Yes. The same British and American naming split applies to the closely related hormone.