The Difference Between Epinephrine and Norepinephrine

Medically Reviewed by Christopher Melinosky, MD on October 24, 2023
4 min read

Epinephrine and norepinephrine have a lot in common. Epinephrine (also called adrenaline), norepinephrine, and dopamine make up a small but important hormone family called catecholamines

Epinephrine and norepinephrine are the hormones behind your “fight-or-flight” response (also called the fight, flight, or freeze response). When you experience stress, these two hormones leap into action. They also play roles in some of your everyday bodily functions. 

Dopamine. Dopamine is a neurotransmitter, a chemical messenger in your brain. This chemical controls your responses to sensory information. When you yank your hand back from a hot stove or when you find yourself craving something sugary in the candy aisle, that’s dopamine at work. 

Dopamine’s roles spread far and wide, including: 

  • Motor control
  • Emotions (pleasure or dislike)
  • Thought-processing

A dopamine imbalance can lead to a loss of motor control (such as Parkinson’s disease), addiction, ADHD, and schizophrenia.

Epinephrine and norepinephrine. These two hormones work together in stressful situations to increase blood flow throughout your body. Some of the changes that occur are: 

  • Increased heart rate
  • Increase the amount of blood pumping from your heart
  • Increased blood pressure

Additionally, they break down fat and increase blood sugar (glucose) levels to give your body more energy. 

You may think of adrenaline as a mysterious chemical that makes you focused and strong enough to lift a car. This isn’t far from the truth, but there’s a little more to the story.

Fight or flight. When you experience stress, your heartbeat quickens, you start to sweat, and you feel the need to get away. This is the fight-or-flight response, at the heart of which is adrenaline. 

Where epinephrine is produced. Like the other catecholamine hormones, adrenaline is produced in the adrenal glands. Within minutes of experiencing stress, adrenaline is sent into your blood toward other organs to cause certain responses.

Epinephrine’s effects on your body. When epinephrine is released, it causes specific reactions in your body. These are intended to ensure your survival but can be a problem if you aren’t in a stressful situation. Some of the effects of adrenaline include: 

  • Dilations of your air passages to take in more oxygen
  • Contracting blood vessels to redirect blood flow to important muscles and organs, such as the heart and lungs
  • Reduced ability to feel pain
  • Increase in strength and physical performance
  • Heightened awareness and focus

Epinephrine injections. Epi-pen shots are commonly used to treat a life-threatening allergic reaction or anaphylaxis. Epinephrine injection is an injection system that is prefilled with a liquid solution of the hormone epinephrine. 

Treating anaphylaxis. Symptoms of a mild allergic reaction include hives, itching, and swelling. Symptoms of anaphylaxis are much more severe, can be life-threatening, and vary between each occurrence. Some symptoms of anaphylaxis include: 

  • Swelling or tightening of the throat
  • Difficulty breathing
  • Shortness of breath
  • Wheezing or coughing
  • Lightheadedness or fainting
  • Abdominal cramps
  • Nausea, vomiting, or diarrhea

Epinephrine injection is the first line of treatment for anaphylaxis. Epinephrine's roles regarding blood flow and oxygen intake help fight the symptoms of anaphylaxis. However, epinephrine injection isn’t the final treatment option, and further medical assistance is necessary. 

Norepinephrine (sometimes referred to as noradrenaline) is a neurotransmitter and hormone that responds to stress and low blood pressure. It also plays a role in managing your ability and your ability to focus.

Fight or flight. When working alongside adrenaline, norepinephrine supports the fight-or-flight response by increasing your heart rate, breaking down fat, and increasing glucose levels. It gives your brain and body the energy it needs to take action. 

Biorhythms. Norepinephrine works to maintain your sleep-wake cycles. It helps you wake up in the morning, improves your attention, and helps you focus throughout the day. 

Norepinephrine imbalances. An imbalance of norepinephrine (too much or too little) can have an impact on your mental and emotional health. Conditions such as depression, anxiety, addiction, substance abuse, and post-traumatic stress disorder are caused by an imbalance of norepinephrine. 

A surge of norepinephrine can cause feelings of happiness and euphoria. However, a surge can also lead to panic attacks, raised blood pressure, and hyperactivity. A lack of norepinephrine can cause lethargy, fatigue, lack of focus, attention deficit hyperactivity disorder (ADHD), and depression. 

You will often find norepinephrine at work treating low blood pressure (hypotension) due to a life-threatening complication or alongside serotonin in antidepressants. It is administered as epi-drip IVs.

Serotonin and norepinephrine reuptake inhibitors (SNRIs) are an antidepressant. SNRIs work by altering the brain chemistry of your serotonin (a “feel good” hormone) and norepinephrine neurotransmitters. This process helps to regulate your mood and relieve depression symptoms. 

Getting norepinephrine naturally. You can help your body and brain produce more serotonin and norepinephrine through exercise, sleep, feeling accomplished, enjoying music, and meditation.