What does epinephrine mean?
Epinephrine is a hormone and neurotransmitter produced primarily by the adrenal glands, which sit atop the kidneys. When the body perceives a threat, the brain triggers a rapid release of epinephrine into the bloodstream, producing the familiar 'fight-or-flight' response: heart rate and blood pressure rise, airways open, blood sugar surges, and muscles receive a burst of energy. This makes epinephrine essential to survival, but it also has a critical role in modern medicine. A synthetic version of the hormone is a first-line emergency treatment for anaphylaxis — the severe allergic reaction that can follow exposure to foods such as peanuts or insect stings — and it is likewise used in cardiac arrest and severe asthma attacks. In American English, especially in medical contexts, 'epinephrine' is the preferred term; British English generally uses 'adrenaline'. In casual speech, phrases like 'an adrenaline rush' capture what scientists would describe as a spike in circulating epinephrine.
nounA hormone and neurotransmitter, produced chiefly by the adrenal glands, that increases heart rate, blood pressure, and blood glucose levels as part of the body's 'fight-or-flight' response; it is also used medically as a drug to treat anaphylaxis, cardiac arrest, and severe asthma attacks.
- A hormone secreted by the adrenal medulla that prepares the body for 'fight-or-flight' by raising heart rate, blood pressure, and blood sugar.
- A synthetic form of this hormone, used as a medication to treat anaphylaxis, cardiac arrest, and severe bronchospasm.
- A neurotransmitter released by the sympathetic nervous system.
"The paramedic administered a dose of epinephrine to counteract the patient's anaphylactic reaction."
"An injection of epinephrine can reverse the life-threatening symptoms of a severe allergic reaction within minutes."
"As the lion charged, a surge of epinephrine sharpened her senses and drove her legs faster than she thought possible."
Rarely used; epinephrine is almost always treated as an uncountable mass noun. A plural appears only in technical contexts referring to distinct molecular variants or formulations.
"The lab compared the binding affinities of several synthetic epinephrines."
Your adrenal glands can dump epinephrine into your bloodstream in under two seconds — fast enough to give a mother superhuman strength or let someone outrun danger before their brain has even finished processing it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of epinephrine
The word epinephrine derives from Greek roots: 'epi-' meaning 'upon' and 'nephros' meaning 'kidney', a reference to the hormone's production by the adrenal glands that sit atop the kidneys. It was coined around the turn of the 20th century when Japanese chemist Jokichi Takamine first isolated the hormone in crystalline form and Parke-Davis trademarked the name for the purified product. Its synonym 'adrenaline', coined slightly earlier from Latin roots meaning 'near the kidney', remains the everyday term in most of the world, while epinephrine persists in American pharmacology. Both words reflect the same anatomical insight expressed through different classical languages.
How epinephrine is actually used
Epinephrine is the standard term in American medical and scientific writing; British English typically uses 'adrenaline' instead. The word carries a clinical register — in everyday speech people are more likely to say 'adrenaline rush'. It is an uncountable mass noun in normal usage.
Easily confused with epinephrine
Ephedrine is a different drug that stimulates the release of norepinephrine and is used as a decongestant, whereas epinephrine is the hormone itself used in emergencies like anaphylaxis.