What Is Norepinephrine?

Low levels of this hormone have been shown to play a role in ADHD, depression, and low blood pressure.

Norepinephrine is a naturally occurring chemical in the body that acts as both a stress hormone and neurotransmitter (a substance that sends signals between nerve cells).

It's released into the blood as a stress hormone when the brain perceives that a stressful event has occurred.

As part of the body's response to stress, norepinephrine affects the way the brain pays attention and responds to events. It can also do the following:

• Increase heart rate
• Trigger the release of glucose (sugar) into the blood
• Increase blood flow to muscles

As a neurotransmitter in the central nervous system, norepinephrine increases alertness and arousal, and speeds reaction time.

Norepinephrine has been shown to play a role in a person's mood and ability to concentrate.

Low levels of norepinephrine may lead to conditions such as attention deficit hyperactivity disorder (ADHD), depression, and hypotension (very low blood pressure).

Norepinephrine and ADHD

Norepinephrine and dopamine, another neurotransmitter, help people pay attention and focus in the course of their daily activities.

Low levels of these chemicals in the brain may make it harder to focus, causing symptoms of ADHD.

According to the American Academy of Child and Adolescent Psychology, ADHD can affect areas of the brain that help you solve problems, plan ahead, understand others' actions, and control impulses.

The following medications can help raise levels of norepinephrine and dopamine in the body, helping you focus:

• Ritalin or Concerta (methylphenidate)
• Dexedrine (dextroamphetamine)
• Adderall (amphetamine and dextroamphetamine)

Strattera (atomoxetine), another drug prescribed for ADHD, only raises levels of norepinephrine, not dopamine.

Norepinephrine and Depression

Depression is a serious medical condition that negatively affects how a person feels, thinks, and acts.

People with depression may be prescribed a class of drugs called serotonin-norepinephrine reuptake inhibitors (SNRIs).

These drugs raise levels of norepinephrine and serotonin, another neurotransmitter, in the brain.

Commonly prescribed SNRIs include:

• Effexor (venlafaxine)
• Cymbalta (duloxetine)

Another group of drugs called tricyclic antidepressants may also be prescribed to increase the activity of norepinephrine in the brain.

But these drugs often cause unwanted side effects, such as sedation, dry mouth, constipation, blurred vision, and weight gain.

Norepinephrine and Low Blood Pressure

Norepinephrine is sometimes given intravenously (by IV) to treat hypotension (very low blood pressure) in emergency situations.

Hypotension is usually a sign of shock. One form is septic shock, in which toxins from an infection cause a whole-body inflammatory response.

Another form of shock is neurogenic shock, in which nerve signals throughout the body are disrupted, often due to a spinal cord injury.

Having low pressure can cause you to become dizzy or faint, or — in extreme cases — can damage your heart or brain.

Levophed (norepinephrine bitartrate) is a form of norepinephrine that’s administered in an intensive-care facility through a vein.