What is the main use of norepinephrine in critical care?

October 11, 2025 •

4 min read

As a critical care medication, norepinephrine's main use is as a first-line vasopressor to manage severe hypotension, particularly in conditions like septic shock. The medication works by powerfully constricting blood vessels to raise and maintain adequate blood pressure when fluid resuscitation alone is not enough.

Quick Summary

Norepinephrine is a critical care medication primarily used to manage dangerously low blood pressure in severe, acute hypotensive states. It works by constricting blood vessels to increase systemic vascular resistance and blood pressure.

Key Points

First-line Vasopressor: The primary use of norepinephrine in critical care is as the first-line vasopressor to treat severe hypotension, particularly in septic shock, when fluid administration is ineffective.
Vasoconstriction Mechanism: It raises blood pressure mainly by activating alpha-1 adrenergic receptors, which causes blood vessels to constrict and increases systemic vascular resistance.
Critical Hypotension: Norepinephrine is used in life-threatening low blood pressure (critical hypotension) to maintain organ perfusion and prevent organ failure.
Other Uses: It is also used to manage blood pressure in other hypotensive states, such as neurogenic shock, post-cardiac arrest, and during certain surgical procedures.
Risk of Ischemia: Excessive vasoconstriction from high doses can reduce blood flow to tissues, potentially causing peripheral ischemia and tissue necrosis.
Central vs. Peripheral Use: Due to the risk of extravasation and tissue damage, it is preferably administered via a central venous catheter.

What is Norepinephrine?

Norepinephrine, also known as noradrenaline, is a naturally occurring catecholamine that functions as both a neurotransmitter and a hormone. In the human body, it plays a vital role in the "fight-or-flight" response by mobilizing the brain and body for action. As a medication, however, it is a powerful sympathomimetic drug that mimics these effects to restore hemodynamic stability in critically ill patients. The synthetic form is commonly known by the brand name Levophed. Its pharmacological action is centered on its ability to stimulate adrenergic receptors throughout the body, particularly in the cardiovascular system.

The Main Medical Use: Treating Severe Hypotension

The central role of norepinephrine in medicine is to treat life-threateningly low blood pressure, or hypotension, that can arise from various medical emergencies. In these scenarios, normal blood pressure is necessary to ensure adequate blood flow and oxygenation to vital organs like the brain, heart, and kidneys. When blood pressure drops to dangerously low levels, organ perfusion is compromised, leading to organ failure and potentially death. Norepinephrine is administered intravenously in a hospital or critical care setting to rapidly counteract this effect.

Common conditions treated with norepinephrine:

Septic Shock: This is the most common indication for norepinephrine. Sepsis is a severe infection that causes widespread inflammation, leading to profound vasodilation (widening of blood vessels) and a dangerous drop in blood pressure. Norepinephrine is typically the first-line vasopressor used when fluid resuscitation fails to restore blood pressure.
Cardiogenic Shock: When the heart is too weak to pump enough blood to meet the body's needs, norepinephrine can be used. It helps increase cardiac output and contractility, though caution is required due to its vasoconstrictive effects.
Neurogenic Shock: Resulting from a severe spinal cord injury, this type of shock disrupts the sympathetic nervous system's control of blood vessel tone. Norepinephrine is used to restore vascular tone and increase blood pressure.
Post-Cardiac Arrest: Following successful cardiopulmonary resuscitation (CPR), patients often experience severe hypotension. Norepinephrine is used to support blood pressure and improve coronary perfusion.
Drug Reactions and Spinal Anesthesia: Certain drug reactions or spinal anesthesia can cause a sudden and severe drop in blood pressure, requiring vasopressor support.

How Norepinephrine Works: The Vasopressor Effect

Norepinephrine is a powerful vasoconstrictor, meaning it causes the constriction or narrowing of blood vessels. This effect is primarily mediated by its activation of alpha-1 adrenergic receptors located on the smooth muscle of arteries and veins. By increasing systemic vascular resistance, norepinephrine effectively raises blood pressure throughout the body.

Beyond its potent alpha-1 effects, norepinephrine also activates beta-1 adrenergic receptors in the heart, leading to a modest increase in heart rate and contractility. While this contributes to blood pressure, its primary and most pronounced effect is on vascular tone. The combination of increased cardiac output and peripheral vasoconstriction makes it a highly effective agent for treating shock and critical hypotension.

Norepinephrine vs. Epinephrine

Norepinephrine and epinephrine (adrenaline) are closely related catecholamines but have distinct medical applications due to their different receptor affinities. The following table highlights the key differences:


Feature	Norepinephrine (Noradrenaline)	Epinephrine (Adrenaline)
Receptor Affinity	Primarily alpha receptors (strong vasoconstriction), lesser beta-1 effect	Stronger effect on beta-1 (heart) and beta-2 (lungs) receptors, also affects alpha receptors
Primary Function	Increase and maintain blood pressure by constricting blood vessels	Wider-ranging effects, including increasing heart rate, improving breathing, and increasing glucose levels
Main Medical Use	First-line vasopressor for septic shock and critical hypotension	Used for severe allergic reactions (anaphylaxis), cardiac arrest, and severe asthma attacks
Effect on Vascular Tone	Strong vasoconstriction, increasing systemic vascular resistance	Also causes vasoconstriction but promotes vasodilation in skeletal muscle arteries via beta-2 receptors

Side Effects and Risks

Given its powerful vasoconstrictive properties, norepinephrine carries risks, particularly when administered at high doses or improperly. Healthcare professionals must carefully balance the need to raise blood pressure with the risk of adverse effects. Potential risks include:

Ischemia: Excessive vasoconstriction can reduce blood flow to peripheral tissues, potentially leading to limb or organ damage.
Hypertension: Overdosing can cause dangerously high blood pressure, leading to severe headache, vision problems, and irregular heartbeats.
Cardiac Arrhythmias: Norepinephrine can cause rapid, slow, or irregular heart rhythms.
Extravasation: Leakage of the medication from the intravenous infusion site into surrounding tissue can cause local skin and tissue damage, highlighting the need for central line administration in most cases.

Conclusion

While a naturally occurring neurotransmitter, norepinephrine's main use in a clinical setting is as a life-saving medication. As a potent vasopressor, it is the standard first-line treatment for severe hypotension, particularly in septic shock, when standard fluid resuscitation is insufficient. Its powerful ability to constrict blood vessels and increase cardiac contractility helps restore blood pressure and ensure proper organ perfusion. However, its use requires careful monitoring to balance its vital effects with potential risks like excessive vasoconstriction. This crucial medication remains a cornerstone of critical care medicine for managing acute hypotensive emergencies. For more information on its role in the body's stress response, see the Cleveland Clinic's resource on norepinephrine's functions.

Frequently Asked Questions

Norepinephrine works primarily by stimulating alpha-1 adrenergic receptors on blood vessel walls, causing them to constrict. This increases the pressure within the circulatory system, which raises overall blood pressure.

While both are catecholamines, norepinephrine is a more potent vasoconstrictor that primarily affects blood vessels, making it ideal for septic shock. Epinephrine has broader effects, acting more strongly on the heart and lungs, and is typically used for severe allergic reactions and cardiac arrest.

As a medication, norepinephrine is used primarily in acute, life-threatening hypotensive states within a hospital or critical care environment. However, as a natural neurotransmitter, it is involved in various bodily functions, including regulating attention and alertness.

Common side effects include headache, anxiety, and changes in heart rate. More serious side effects can involve high blood pressure, irregular heart rhythms, and tissue damage if the infusion leaks from the vein.

Medical guidelines, including the Surviving Sepsis Campaign, recommend norepinephrine as the first-line vasopressor for septic shock over dopamine because it has shown improved survival benefits in this patient population. Dopamine is now reserved for more specific situations.

If norepinephrine leaks from the IV line (extravasation), it can cause severe local vasoconstriction and tissue ischemia, which can lead to pain, swelling, and even necrosis (tissue death). A specific antidote can be infiltrated into the affected area to counteract this effect.

In a medical setting, norepinephrine is administered as a continuous intravenous (IV) infusion, meaning it is delivered steadily into a vein over time. A central venous catheter is the preferred route to minimize the risk of extravasation.