What Is Adrenaline?

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Adrenaline, also known as epinephrine, is a type of catecholamine (stress hormone) that is naturally secreted in large amounts when an individual experiences fear, anxiety, or stress, resulting in the fight-or-flight response, also called adrenaline rush.

Adrenaline prepares the body to react to or retreat from a threat by increasing blood circulation, breathing, and metabolism. While this response is crucial to survival, over-exposure to adrenaline can be damaging to one's health.

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Close up of a senior woman and her instructor doing tandem skydiving.  Geber86, Getty Images

How It Works 

Adrenaline works by stimulating the sympathetic nervous system. It is released from the adrenal glands (the triangular gland sitting on top of each kidney) during physically and emotionally stressful or threatening situations. This is a natural response of the body that requires extra energy to quite literally fight (endure greater physical strain) or flee (temporarily exert excess stamina).

During a stressful situation, adrenaline is rapidly released into the blood, sending impulses to organs to create a specific response, including:

  • Accelerating heart rate
  • Increasing the force of heart contractions
  • Improving blood flow to major muscle groups like the heart and lungs and the brain
  • Opening (relaxing) the airways
  • Assisting in glucose (sugar) metabolism
  • Controlling the squeezing of blood vessels (vasoconstriction)
  • Maintaining blood pressure or increasing it during stress

The body's ability to feel pain also decreases, which is why someone can continue running from danger even when they are injured. Adrenaline causes a noticeable increase in strength and performance, as well as heightened awareness during stressful times.

A typical adrenaline rush has a sudden onset and lasts a short span of time (about an hour after the stress subsides). So if you're experiencing persisting symptoms of an adrenaline rush in the absence of environmental triggers, this may be a sign of an underlying disorder.


Symptoms of an adrenaline rush include:

  • A pounding sensation in your heart
  • Rapid heart rate
  • Fast breathing or hyperventilation
  • Shallow breathing
  • Increased sweating
  • Increased ability to run and lift heavy objects
  • Dilated pupils
  • Feeling shaky or nervous
  • Trembling or shaking in your arms, legs, and hands
  • Dizziness


Excess levels of adrenaline can cause a number of health problems. Research from Harvard Medical School suggests that chronic stress (meaning repeated stress-response activation) not only contributes to high blood pressure but also promotes the formation of artery-clogging deposits and causes brain changes that may contribute to anxiety, depression, and addiction.

Consistent, long-term exposure to adrenaline can also cause:

  • Digestive problems
  • Cardiovascular disease
  • Weight gain
  • Metabolic issues
  • Headaches
  • Memory and concentration impairment
  • Sleep disorders

Overexposure to adrenaline is usually caused by chronic stress, but some medical conditions can cause an overproduction as well as deficiency of adrenaline. 

Adrenal Gland Tumors

Adrenal gland tumors are nodules that may produce excessive amounts of hormones. It's reported that nodules 4 centimeters or larger and nodules with certain features increase suspicion for malignancy, but both benign and cancerous nodules can produce excess hormones.

Other associated issues include pheochromocytoma, a type of tumor that triggers excess production of adrenaline. It may cause persistent or sporadic high blood pressure that may be difficult to control with regular medications. Aldosteronoma and androgen-producing tumors can also cause stress hormone overproduction.

Obstructive Sleep Apnea

Obstructive sleep apnea is a chronic condition affecting the upper airway and leading to recurrent arousals from sleep, abnormal breathing during sleep, and low levels of oxygen in the blood. As people struggle to breathe in their sleep, their body perceives a lack of oxygen as danger, which then creates a physical stress response. It affects roughly 5%-10% of people across cultures and countries.

Addison's Disease

Addison’s disease is an uncommon but serious adrenal disorder caused by the adrenal glands not producing enough of the hormones cortisol and aldosterone. It affects about one in 100,000 in the United States. It occurs in both men and women equally and in all age groups, but is most common in the 30-50 year-old age range.

Signs of adrenal insufficiency:

  • Weakness
  • Fatigue
  • Dizziness
  • Dark skin (Addison's disease only)
  • Bluish-black color around the nipples, mouth, rectum, scrotum, or vagina (Addison's disease only)
  • Weight loss
  • Fluid loss (dehydration)
  • Lack of appetite
  • Muscle aches
  • Upset stomach (nausea)
  • Vomiting
  • Diarrhea
  • Low blood pressure
  • Low sugar levels
  • In people who menstruate, irregular or no menstrual periods

When to Seek Help

If you are experiencing new-onset or worsening symptoms of adrenal insufficiency, call your doctor. They can order lab tests to rule out other underlying conditions and determine an appropriate course of treatment. 

For more information, visit the National Adrenal Disease Foundation (NADF) at http://www.nadf.us/.


Adrenal Gland Tumors

It is recommended that most tumors, regardless of size, be surgically removed to prevent further issue. These tumors may be removed without large incisions. In some cases, treatment may not be necessary, unless the tumor begins to approaches 5 centimeters. Smaller, benign tumors can be put on watch and observed via repeat CT scans. In other cases, the adrenal glands may need to be removed completely.

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 continuous positive airway pressure, or CPAP, a device that blows air into the airways to keep them open at night.

Addison's Disease

Treating Addison's typically involves replacing the insufficient hormones. For instance, you may be prescribed hydrocortisone pills to replace cortisol or treatment may involve a mix of hormone replacement therapy and lifestyle changes.


For people whose adrenal systems are being triggered by chronic stress, routinely engaging in self-care activities that focus on stress management can be an effective way to calm the nervous system. 

Harvard Medical School says symptoms of stress can take many forms, but recognizing that physical complaints, such as tension headaches, back pain, indigestion, or heart palpitations as potentially caused by stress is important for your overall health.

Some coping activities may include:

  • Deep breathing exercises
  • Meditation
  • Guided imagery
  • Relaxation techniques
  • Yoga poses and stretches

If these at-home strategies do not provide relief, contact a mental health professional and ask if cognitive behavioral therapy (CBT) or other psychotherapeutic approaches may be right for you. A trained therapist can help you change unhealthy thinking that contributes to stress and develop more positive thoughts to reduce stress long-term.

A Word From Verywell

If you are feeling symptoms of excess stress, it's important to reflect on their origin and develop strategies at home or with professionals to counterbalance the excess pressure on your adrenal system. If stress-reduction does not help, you may have an adrenal disorder. When unsure, talking to your doctor is the best way to understand what your current state of health is. Your doctor can order tests, prescribe treatment options, and discuss lifestyle modifications to get you back to feeling your best.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. John Hopkins Medicine. Adrenal Glands.

  2. Hormone Health Network. What Is Adrenaline? Updated November 2018.

  3. EndocrineWeb. What Is Adrenaline? Updated October 25, 2020.

  4. The Cleveland Clinic. Adrenal Disorders.

  5. Harvard Medical School Harvard Health Publishing. Understanding the stress response. Updated July 2020.

  6. John Hopkins Medicine. Adrenal Insufficiency: Addison’s Disease.

  7. The Cleveland Clinic. Adrenal Tumors: Management and Treatment.

  8. Harvard Health Publishing. Weight loss, breathing devices still best for treating obstructive sleep apnea. Updated March 18, 2019.

  9. Harvard Health Publishing. Best ways to manage stress. Published January 2015.