Adrenaline is produced by the adrenal glands, two small glands that sit on top of each kidney. More specifically, adrenaline comes from the inner portion of each adrenal gland, called the medulla. The outer layer, called the cortex, produces different hormones entirely. Your body has two adrenal glands, and together they produce roughly four times more adrenaline than its close chemical relative, noradrenaline.
Where Exactly Adrenaline Is Made
Each adrenal gland has two distinct layers that function almost like separate organs packed into one. The outer cortex produces steroid hormones that regulate metabolism, blood pressure, and sex hormones. The inner medulla is the adrenaline factory. It contains specialized cells called chromaffin cells, which originate from the same type of embryonic tissue that forms parts of the nervous system. This shared origin is why the adrenal medulla responds so directly to nerve signals from the brain.
The medulla produces two closely related hormones: adrenaline (also called epinephrine) and noradrenaline (norepinephrine). Adrenaline makes up about 80% of the output, with noradrenaline accounting for the remaining 20%. Though chemically similar, adrenaline is the more potent of the two.
How Your Body Builds Adrenaline
Adrenaline starts as tyrosine, an amino acid found in protein-rich foods like meat, eggs, and dairy. Inside chromaffin cells, tyrosine goes through four chemical transformations. First, it’s converted into a compound called L-DOPA. Then L-DOPA is converted into dopamine. Dopamine is then converted into noradrenaline. Finally, a specialized enzyme adds a small chemical group to noradrenaline, turning it into adrenaline. That last step is what makes the adrenal medulla unique. Nerve cells throughout your body can produce noradrenaline, but only the adrenal medulla (and a few small brain regions) can complete the final conversion to adrenaline.
What Triggers Adrenaline Release
The brain is the starting point. When it detects a threat or stressor, it sends electrical signals through the sympathetic nervous system directly to the adrenal medulla. This connection is so fast that adrenaline can flood your bloodstream within seconds. The physiologist Walter Cannon first proposed in the early 1900s that the sympathetic nervous system and adrenal glands work together as a single emergency unit, one of the earliest descriptions of what we now call a neuroendocrine system.
Not all stress triggers adrenaline equally. The adrenal medulla responds most strongly to global or metabolic threats: a sudden drop in blood sugar, a dangerous drop in blood pressure, intense exercise that pushes past your aerobic limit, difficulty breathing, or physical shock. Emotional states matter too, but in a specific pattern. Passive, immobilizing fear tends to produce a stronger adrenaline response, while active responses like fighting back or fleeing are more closely tied to noradrenaline release from sympathetic nerves throughout the body. The two systems often work in tandem, but they can also respond independently or even in opposite directions depending on the situation.
What Adrenaline Does to Your Body
Once released, adrenaline acts fast and disappears fast. Its half-life in the bloodstream is less than five minutes, meaning your body breaks down half of it in that time. But those few minutes are enough to reshape how your body operates.
Your heart pumps harder and faster, pushing oxygenated blood toward your muscles. Your airways widen and your breathing deepens, pulling more oxygen into your lungs. Your liver converts stored glycogen into glucose, flooding your bloodstream with quick energy. Blood flow shifts away from your digestive system and skin toward your skeletal muscles. Your pupils dilate. Pain perception dulls. These changes happen simultaneously, and they’re why a surge of adrenaline can feel so dramatic: your entire body reorganizes its priorities in seconds.
The effects fade quickly once the threat passes and adrenaline stops being released. Because of its short half-life, the shaky, jittery feeling after a scare usually subsides within 10 to 20 minutes as the remaining adrenaline is broken down.
Adrenaline vs. Epinephrine
These are two names for the same molecule. “Adrenaline” comes from the Latin name for the adrenal gland (ad + renal, meaning “near the kidney”). “Epinephrine” comes from the Greek (epi + nephros, also meaning “upon the kidney”). In the United States, medical and pharmacological contexts favor “epinephrine,” while “adrenaline” is more common in everyday language and in many countries outside the U.S. If you see either term on a medical label or in a textbook, they refer to the same hormone.
When Adrenaline Production Goes Wrong
The most well-known disorder of adrenaline overproduction is a rare tumor called a pheochromocytoma, which grows in the adrenal medulla’s chromaffin cells. These tumors produce uncontrolled surges of adrenaline and noradrenaline, causing episodes of severe high blood pressure, rapid heartbeat, sweating, headaches, and intense anxiety. Doctors screen for this condition by measuring breakdown products of adrenaline in the blood, since adrenaline itself disappears too quickly to measure reliably. The reference ranges for these breakdown products increase with age, so what’s considered normal for a 25-year-old is different from what’s normal for someone over 60.
On the other end of the spectrum, people whose adrenal glands are damaged or surgically removed may produce too little adrenaline. This is less immediately dangerous than cortisol deficiency (which the adrenal cortex produces), but it can impair the body’s ability to respond to low blood sugar and other metabolic emergencies.