epinephrine

American  

[ep-uh-nef-rin, -reen] / ˌɛp əˈnɛf rɪn, -rin /

Or epinephrin

noun

1. Also called adrenaline.  Biochemistry. a hormone secreted by the adrenal medulla upon stimulation by the central nervous system in response to stress, as anger or fear, and acting to increase heart rate, blood pressure, cardiac output, and carbohydrate metabolism.

2. Pharmacology. Also Adrenalin a commercial form of this substance, extracted from the adrenal glands of sheep and cattle, or synthesized: used chiefly as a heart stimulant, to constrict the blood vessels, and to relax the bronchi in asthma.

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epinephrine British  

/ ˌɛpɪˈnɛfrɪn, -riːn /

noun

1. a US name for adrenaline

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epinephrine Scientific  

/ ĕp′ə-nĕf′rĭn /

1. A hormone that is secreted by the adrenal gland in response to physical or mental stress, as from fear, and is regulated by the autonomic nervous system. The release of epinephrine causes an increase in heart rate, blood pressure, and respiratory rate. Epinephrine also raises glucose levels in the blood for use as fuel when more alertness or greater physical effort is needed. Also called adrenaline. Chemical formula: C ₉ H ₁₃ NO ₃ .

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Etymology

Origin of epinephrine

First recorded in 1895–1900; epi- + Greek nephr ( ós ) kidney + -ine ²

Compare meaning

How does epinephrine compare to similar and commonly confused words? Explore the most common comparisons:

• epinephrine vs. norepinephrine
• epinephrine vs. adrenaline

Explanation

Epinephrine is a hormone that's released by the adrenal glands in response to stress. If you've ever felt your heart pounding fast after hearing a scary sound in the dark, you've experienced a surge of epinephrine. Epinephrine is another name for adrenaline. This is the hormone involved in "fight or flight" responses to dangerous or scary situations. It's also the name of a synthetic form of the hormone that's used as a medication. Someone who's having a severe allergic reaction to peanuts or shellfish might need an injection of epinephrine to reverse the symptoms. The Greek roots of epinephrine mean "upon the kidney," a reference to the location of the adrenal glands.

Example Sentences

At one point, he needed epinephrine because he nearly went into cardiac arrest.

From Los Angeles Times • Mar. 6, 2025

Although a highly accurate diagnostic test, patients often experience anaphylaxis during oral food challenges necessitating an epinephrine injection.

From Science Daily • Nov. 7, 2023

Results will help pinpoint values associated with anaphylaxis to determine "stopping rules" to end oral food challenges, hopefully reducing the need for epinephrine injections.

From Science Daily • Nov. 7, 2023

AB 1651, by Assembly member Kate Sanchez, a Republican from Rancho Santa Margarita, will require schools to have emergency epinephrine auto-injectors for use by school nurses or trained volunteers to treat life-threatening anaphylactic reactions.

From Salon • Oct. 26, 2023

Vessels become hyperreactive to epinephrine so that physiologic concentrations suddenly possess necrotizing properties.

From "The Lives of a Cell" by Lewis Thomas