Norepinephrine is a naturally occurring chemical in the body that acts as both a hormone and neurotransmitter (a substance that sends signals between nerve cells), according to the Endocrine Society.
As a hormone, norepinephrine (also called noradrenaline) is released by your adrenal glands, which sit atop your kidneys, says Cleveland Clinic. As a neurotransmitter, norepinephrine is derived from dopamine (another neurotransmitter), and released by nerve cells in the brain and near your spinal cord.
Common Questions & Answers
Norepinephrine works as both a hormone and a neurotransmitter. It plays an important role in the fight-or-flight response, the body’s emergency response to danger or perceived danger. It also boosts alertness, arousal, and attention, and affects your sleep-wake cycle, mood, and memory.
Low norepinephrine levels have been associated with low mood. People with depression may be treated with a class of medications called serotonin and norepinephrine reuptake inhibitors (SNRIs).
How Norepinephrine Affects Your Body
Stress triggers the release of norepinephrine and adrenaline. This is known as the fight-or-flight response, the body’s emergency response to danger or perceived danger, per Cleveland Clinic. This response causes several changes in the body, including:
- Pupils dilate
- Skin turns pale
- Heart pumps faster
- Blood pressure increases
- Muscles receive more blood flow and oxygen
- You get a burst of energy
- Breathing gets deeper and faster
Norepinephrine also plays other roles in the body. These include:
- Increasing alertness, arousal, and attention
- Affecting your sleep-wake cycle (helping you wake up), mood, and memory
Norepinephrine and Your Health
Per the Cleveland Clinic, low levels of norepinephrine can also lead to various health conditions, including:
- Anxiety
- Depression
- Attention deficit hyperactivity disorder (ADHD)
- Headache
- Memory problems
- Trouble sleeping
- Low blood pressure (hypotension)
- Low blood sugar (hypoglycemia)
- Changes in blood pressure and heart rate
- Dopamine beta-hydroxylase deficiency, a rare disease that prevents your body from converting dopamine into norepinephrine
Health conditions that can result from high levels of norepinephrine include:
- High blood pressure (hypertension)
- Rapid or irregular heartbeat
- Excessive sweating
- Cold or pale skin
- Severe headache
- Nervousness, jitters
- Pheochromocytoma, an adrenal gland tumor
- Increased risk of heart, blood vessel, and kidney damage
How Can Norepinephrine Be Used as a Medication?
Norepinephrine can be used as a medication for several conditions, including ADHD, depression, and low blood pressure.
Norepinephrine and ADHD
ADHD medications target norepinephrine and dopamine, both of which affect your attention and concentration, according to KidsHealth.
The following common medications for ADHD increase both norepinephrine and dopamine, per Mental Health America:
Atomoxetine (Strattera), another drug prescribed for ADHD, raises levels of norepinephrine but not dopamine.
The most common side effects of ADHD medications are loss of appetite and trouble sleeping, per KidsHealth. Other ADHD side effects include jitteriness, irritability, moodiness, headache, stomachaches, fast heart rate, and high blood pressure.
RELATED: What Are the Treatments for ADHD?
Norepinephrine and Depression
Low levels of norepinephrine have been associated with low mood.
People with major depressive disorder — a serious medical condition that negatively affects how a person feels, thinks, and acts — may be prescribed a class of drugs called serotonin-norepinephrine reuptake inhibitors (SNRIs), which keep norepinephrine and serotonin from being reabsorbed and stored in nerve endings, per Mental Health America.
According to Mayo Clinic, commonly prescribed SNRIs include:
The most common side effects of SNRIs are nausea, dry mouth, dizziness, headache, and excessive sweating, per the Mayo Clinic. Other possible side effects include fatigue, constipation, insomnia, changes in sexual function, and loss of appetite. Sometimes children, teenagers, and young adults under age 25 may experience an increase in suicidal thoughts or behavior when taking antidepressants.
SNRIs may increase your bleeding risk, particularly when you're taking other medications that also increase the risk of bleeding, such as ibuprofen (Advil, Motrin IB), aspirin, and blood thinners.
In rare cases, certain antidepressants can cause a serious condition called serotonin syndrome. This typically occurs when two medications that raise serotonin are taken at the same time, such as other antidepressants, certain pain or headache medications, or St. John's wort.
Another group of drugs called tricyclic antidepressants may also be prescribed to increase norepinephrine.
But these older drugs often cause side effects such as dry mouth, constipation, and weight gain, notes Mental Health America.
Norepinephrine and Low Blood Pressure
Norepinephrine injection (Levophed) is used to increase blood pressure in people who have severe, acute hypotension, or short-term low blood pressure, according to Mayo Clinic. This medication, which is administered through a vein, should be given only by or under the direct supervision of your doctor.
More common side effects of Levophed include blurred vision; chest pain or discomfort; headache; light-headedness, dizziness, or fainting; nervousness; pounding in the ears; slow, fast, or irregular heartbeat; and unusual tiredness or weakness.
Using Levophed with the following medicines is not recommended.
- Dihydroergotamine
- Isocarboxazid
- Phenelzine
- Tranylcypromine
Additional reporting by Jennifer D'Angelo Friedman.
Editorial Sources and Fact-Checking
- Adrenal Hormones. Endocrine Society. January 24, 2022.
- Norepinephrine (Noradrenaline). Cleveland Clinic. March 27, 2022.
- ADHD Medicines. KidsHealth. March 2018.
- What Is Noradrenaline? Mental Health America.
- Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs). Mayo Clinic. October 5, 2019.
- Norepinephrine (Intravenous Route). Mayo Clinic. January 1, 2023.