What Is Adrenaline?

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Adrenaline, also known as epinephrine, is a type of stress hormone that is secreted in large amounts whenever a person experiences fear, anxiety, or stress. It is the hormone that triggers the fight-or-flight response, also known as an "adrenaline rush."

Adrenaline prepares the body to either fight or flee from danger by increasing blood circulation and breathing. While this response is crucial to survival, over-exposure to adrenaline can be damaging to a person's health.

This article looks at how adrenaline works in the body, including the symptoms of an adrenaline "rush," as well as the causes and consequences of adrenaline overproduction and adrenaline deficiency.

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How Adrenaline Works 

Adrenaline works by stimulating a part of the nervous system known as the sympathetic nervous system that regulates the body's unconscious actions. It is released by the adrenal glands (the triangular glands sitting on top of each kidney) during physically or emotionally stressful situations.

Adrenaline is the hormone that is responsible for the body's fight-or-flight response. When adrenaline is released, it affects the body in six keys ways:

  • It causes air passages to widen (dilate) to provide the muscles with the oxygen they need to either fight or flee danger.
  • It causes blood vessels to narrow (contract) to redirect blood flow to major muscle groups, including the heart and lungs.
  • It causes the heart rate to speed up and the heart to contract more forcefully so that more oxygen is delivered to muscles and tissues.
  • It causes the liver to release blood sugar (glucose), which provides the body with energy.
  • It causes the pupils of your eyes to dilate (known as stress-induced mydriasis) so that you see more clearly even in the dark.
  • It reduces the perception of pain (known as stress-induced analgesia) so that you can continue fighting or fleeing even if you are injured.

Adrenaline is not only released when there is actual danger but also during moments of extreme stress. This may include taking a test, watching a scary movie, speaking in public, going out on a date, riding a rollercoaster, or doing an extreme sport like skydiving.


Adrenaline is a hormone that can cause an increase in strength and performance during moments of stress as well as heightened awareness, visual sharpness, and pain tolerance.


The typical "adrenaline rush" starts immediately and can last for up to an hour after the stress subsides. Common symptoms include:

  • A pounding heart
  • Rapid heart rate
  • Rapid and shallow breathing
  • Increased sweating
  • Dilated pupils
  • Increased ability to run or lift heavy objects
  • Feeling shaky or nervous
  • Trembling or shaking
  • Dizziness
  • Dry mouth


There are times when the body will release adrenaline when it is under emotional stress but not facing any real danger. When this occurs, the release of glucose into the bloodstream can accumulate rather than being burned off, causing symptoms like restlessness and irritability. You may also experience dizziness, lightheadedness, vision changes, sweating, and a pounding heart.

Persistently high adrenaline levels caused by chronic (ongoing) psychological stress can cause serious health problems over time, including:

According to a 2017 study in the medical journal Lancet, emotional stress was associated with a 59% increase in the risk of a cardiovascular event in people with heart disease.

Producing too little adrenaline also has health consequences. While this is rare, conditions that either damage or destroy the adrenal glands (or require the removal of the adrenal glands) can lead to symptoms such as low blood pressure, low blood sugar, chronic fatigue, lack of energy, muscle weakness, nausea, diarrhea, dehydration, depression, and irregular or missed periods.


Persistently high adrenaline levels caused by chronic stress or other conditions can lead to serious health concerns like high blood pressure, cardiovascular disease, digestion problems, and depression.


Medical conditions that cause the overproduction (hypersecretion) or underproduction (insufficiency) of adrenaline are uncommon but can occur. These conditions either directly or indirectly affect the adrenal glands.

Adrenaline Hypersecretion

There are several conditions that can cause the adrenal glands to release too much adrenaline inappropriately. Chief among these are:

  • Cushing syndrome: A disorder that causes the overproduction of the stress hormone cortisol as well as the hormones adrenaline and aldosterone. Cortisol and aldosterone are also produced by the adrenal glands, while the pituitary gland directs how much is produced. Common causes include the prolonged use of corticosteroid (steroid) drugs and pituitary gland tumors.
  • Adrenal gland tumors: Tumors of the adrenal glands can also cause the hypersecretion of adrenaline and cortisol. The tumors are usually benign (cancerous) but can sometimes be cancerous. A type of tumor called a pheochromocytoma affects cells responsible for producing adrenaline, leading to the hypersecretion of adrenaline.
  • Obstructive sleep apnea: This chronic sleeping disorder, which causes the momentary disruption of breathing, can indirectly cause adrenal hypersecretion by triggering a stress response as you gasp for air. If left untreated, obstructive sleep apnea can increase the risk of diabetes, high blood pressure, and atherosclerosis due in part to the ongoing overproduction of stress hormones.

Adrenaline Insufficiency

Adrenaline insufficiency is uncommon and rarely occurs on its own. It is typically the result of a condition known as Addison's disease in which the adrenal glands produced too little (or none) of the stress hormones.

Also known as adrenal insufficiency, Addison's disease is caused by conditions that affect your adrenal glands. The cause may be primary (meaning the result of damage to the adrenal glands) or secondary (caused by a problem with the pituitary gland, which regulates hormone production).

Causes of primary adrenal insufficiency include:

Causes of secondary adrenal insufficiency include:

Primary vs. Secondary Adrenal Insufficiency

The symptoms of primary and secondary adrenal insufficiency are similar, but, with primary adrenal insufficiency, a person is more likely to experience hyperpigmentation (darkening of the skin), low blood pressure, and severe dehydration. These are uncommon with secondary adrenal insufficiency.

Adrenal insufficiency can sometimes become severe and lead to a potentially life-threatening condition known as an adrenal crisis. Symptoms include rapid heart rate, rapid breathing, abdominal or flank pain, dizziness, weakness, profuse sweating, high fever, nausea and vomiting, confusion, and unconsciousness.

An adrenal crisis is a medical emergency that can lead to coma and death if not treated immediately.


The treatment of adrenaline hypersecretion and adrenaline insufficiency varies by the underlying cause. The treatment may involve lifestyle changes, medications, and, in some cases, surgery.

Hormonal disorders are commonly treated by an endocrinologist who specializes in disorders of the endocrine system.

Cushing Syndrome

The treatment of Cushing syndrome may involve gradually tapering down the dose of steroids in people treated with drugs like prednisone. If the cause is a pituitary tumor, your healthcare provider will likely recommend that the gland be removed surgically (which can cure the condition in 90% of cases).

Adrenal Gland Tumors

It is recommended that most tumors, regardless of size, be surgically removed. Some healthcare providers will take a watch-and-wait approach and only consider surgery when the tumor approaches 5 centimeters (2 inches) in size.

Obstructive Sleep Apnea

Treatment of obstructive sleep apnea includes weight loss. According to Harvard Medical School, even losing 10% of body weight can have a big effect on sleep apnea. Since weight loss takes time, the first-line treatment commonly includes a device called continuous positive airway pressure (CPAP), which blows air into the airways to keep them open at night.

Addison's Disease

Addison's disease is typically treated with hormone replacement therapy. Options include Cortef (hydrocortisone), prednisone, or methylprednisolone tablets to replace cortisol or Florinef (fludrocortisone acetate) to replace aldosterone. An increased intake of salt (sodium) may also be required, particularly during exercise or when you have gastrointestinal problems like diarrhea.


Chronic stress can reap havoc on a person's health and well-being. Regularly engaging in stress reduction strategies can help you better control stress and potentially lower your risk of heart disease. This includes routine exercise, which not only improves your cardiovascular health but can improve your moods due to the release of "feel-good" hormones called endorphins.

Popular stress-reduction strategies include:

  • Yoga
  • Tai chi
  • Deep breathing exercises
  • Meditation
  • Guided imagery
  • Progressive muscle relaxation (PMR)
  • Biofeedback


Adrenaline is a hormone also known as epinephrine that is released by the adrenal glands as part of the “fight or flight” response. When faced with a threat or stress, the hormone stimulates the nervous system to rapidly respond to the crisis.

Although adrenaline is produced as a normal response to any threat, perceived or real, it can cause serious health problems if the hormone is persistently elevated or deficient. There a medical conditions (like Cushing's syndrome and adrenal gland tumors) that can cause both of these things and require a medical diagnosis and treatment to resolve.

A Word From Verywell

If you have symptoms of Cushing syndrome or Addison's disease, it is important to see a practitioner who can order tests to confirm your suspicions. If you are experiencing insomnia, jitteriness, heart palpitations, and other stress-related symptoms, you should also speak with a healthcare provider who may offer tips on how to better manage your stress.

If self-help strategies fail to provide relief, do not hesitate to ask your healthcare provider for a referral to a therapist or psychiatrist who can provide one-on-one or group counseling to better target and address the causes of your stress. For extreme cases, medications can be prescribed.

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13 Sources
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