Understanding the Body’s “Fight or Flight” Hormone

When you’re faced with danger, stress, or excitement, your heart starts racing, your breathing quickens, and your muscles feel ready for action. These rapid responses are made possible by a powerful hormone called epinephrine, more commonly known as adrenaline.

Adrenaline is one of the body’s most well-known hormones and for good reason. It is essential for survival, allowing humans to respond quickly to threats by triggering a wave of physical and mental changes known as the “fight or flight” response.

In this article, we explore what adrenaline is, how it works, and what happens when there’s too much or too little of it in the body.

What Is Epinephrine (Adrenaline)?

Epinephrine (also called adrenaline) is a hormone and neurotransmitter produced by the adrenal glands, which are located above your kidneys. It is released into the bloodstream during times of physical or emotional stress, helping the body respond to immediate danger or high-stress situations.

Epinephrine is part of the body’s sympathetic nervous system, a branch of the autonomic nervous system that controls involuntary responses like heart rate, breathing, and digestion.

How Does Adrenaline Work?

When the brain perceives a threat real or perceived it sends a signal to the adrenal glands to release epinephrine into the bloodstream. Once released, adrenaline acts on various organs and tissues to:

Increase heart rate and blood pressure: To deliver more oxygen to muscles
Expand airways: Making it easier to breathe and take in more oxygen
Boost energy supply: By stimulating the liver to break down glycogen into glucose
Dilate pupils: Enhancing vision in low-light situations
Redirect blood flow: Moving blood away from the digestive system and toward muscles and the brain

This response prepares the body for quick action, whether to escape a threat or confront it head-on.

Functions of Epinephrine

Epinephrine serves several critical roles in the body, including:

Stress Response
- The primary hormone involved in the “fight or flight” reaction to danger.
- Acts within seconds to optimize the body’s performance under pressure.
Energy Mobilization
- Stimulates glucose release for instant energy.
- Increases fat breakdown for longer-term energy needs.
Cardiovascular Regulation
- Raises heart rate and strengthens heart contractions.
- Helps maintain blood pressure during stress or injury.
Respiratory Support
- Dilates bronchial passages to improve oxygen intake.
- Used medically in conditions like asthma and severe allergic reactions.

Medical Uses of Epinephrine

Adrenaline is not only vital in natural responses but also used in life-saving medical treatments:

1. Anaphylaxis

Epinephrine is the first-line treatment for severe allergic reactions (e.g., to peanuts, bee stings, or medications).
It works quickly to reduce airway swelling, raise blood pressure, and improve breathing.
Commonly administered via epinephrine auto-injectors (like EpiPen).

2. Cardiac Arrest

Used in emergency settings to stimulate the heart during cardiopulmonary resuscitation (CPR).

3. Asthma Attacks

Administered in some emergency cases to open airways and restore normal breathing.

4. Local Anesthesia

Sometimes added to anesthetic injections to constrict blood vessels and prolong numbing effects.

What Happens When There’s Too Much Adrenaline?

Excessive or prolonged adrenaline release can cause a range of physical and emotional symptoms, including:

Rapid heartbeat (tachycardia)
High blood pressure (hypertension)
Anxiety, nervousness, or panic attacks
Sweating and shaking
Headaches or dizziness
Insomnia or sleep disturbances
Chest pain (in severe cases)

Long-term high levels of adrenaline often due to chronic stress can lead to health complications such as:

Heart disease
Immune suppression
Weight gain (especially belly fat)
Mood disorders like anxiety or depression

What Causes Excess Adrenaline?

Some possible causes of increased epinephrine levels include:

Chronic psychological stress
Panic disorder or anxiety conditions
Caffeine or stimulant overuse
Hyperthyroidism
Adrenal tumors, such as pheochromocytoma (a rare but serious condition)
Severe illness, trauma, or pain

What Happens When There’s Too Little Adrenaline?

Epinephrine deficiency is rare, but when it does occur, it may lead to:

Low blood pressure (especially during stress)
Dizziness or fainting
Fatigue and lack of energy
Poor stress tolerance

Conditions such as adrenal insufficiency (e.g., Addison’s disease) may impair the production of adrenaline and other adrenal hormones.

How Is Epinephrine Imbalance Diagnosed?

Epinephrine levels can be measured through blood or urine tests, especially when conditions like pheochromocytoma or adrenal gland disorders are suspected.

Doctors may also perform:

Blood pressure monitoring
Imaging (CT, MRI) of the adrenal glands
Hormone panel testing for cortisol, aldosterone, and ACTH

At Erdem Hospital, with over 37 years of clinical experience, our endocrinology team provides thorough evaluations for adrenal gland and hormone-related conditions, ensuring accurate diagnosis and personalized treatment.

Managing Adrenaline Imbalance

Too much adrenaline?

Practice stress-reduction techniques like mindfulness, deep breathing, or yoga.
Get regular exercise (but avoid overtraining).
Limit caffeine and stimulant use.
Seek help for anxiety or panic disorders.

Too little adrenaline?

Consult an endocrinologist for hormonal evaluation.
Treat underlying adrenal or pituitary disorders.
Hormone replacement therapy may be required in cases like Addison’s disease.

Final Thoughts

Epinephrine (adrenaline) is a remarkable hormone that enables the body to perform under stress, react to emergencies, and maintain critical functions. While it’s famous for its “rush” during dangerous or exciting situations, it also plays a quiet but crucial role in daily life regulating heart rate, supporting breathing, and helping maintain balance during physical and emotional challenges.

If you’re experiencing symptoms of adrenaline imbalance such as frequent panic, fatigue, dizziness, or unexplained blood pressure changes it’s worth consulting a healthcare provider to investigate further.

At Erdem Hospital, we are committed to helping patients understand their hormones and restore optimal health through evidence-based, compassionate care.