Updated July 2026 · 9 min read

Epinephrine: The ICU Nurse's Guide

Part of the ICU Pharmacology Hub — browse every related guide in one place.

Epinephrine is the most versatile — and most dangerous to confuse — drug on the code cart. The same molecule stops anaphylaxis, restarts a heart, and props up a failing circulation, but the concentration and route change completely depending on which job you're asking it to do. The single most important skill with epinephrine is knowing which concentration you're holding and why.

How epinephrine works

Epinephrine stimulates alpha-1, beta-1, and beta-2 receptors. Beta-1 stimulation increases heart rate and contractility; beta-2 stimulation relaxes bronchial smooth muscle and, at low doses, can actually dilate some vascular beds. Alpha-1 stimulation constricts blood vessels and raises systemic vascular resistance. Because the receptor mix shifts with dose, epinephrine behaves like several different drugs stacked into one vial. Low doses look like an inotrope; high doses look like a vasopressor.

The concentrations you must never confuse

Epinephrine errors almost always come from grabbing the wrong concentration. Learn these cold.

Cardiac arrest dosing

In ACLS, epinephrine is 1 mg IV/IO of the 0.1 mg/mL concentration every 3–5 minutes during CPR, followed by a saline flush and a limb raise to speed central delivery. In non-shockable rhythms (asystole, PEA), give it as early as possible; in shockable rhythms (VF/pVT), it comes after the first shock or two while defibrillation and compressions remain the priority. The mechanism that matters in arrest is alpha-mediated vasoconstriction, which raises aortic diastolic pressure and improves coronary perfusion during compressions.

Anaphylaxis dosing

Anaphylaxis is the one time you reach for the 1 mg/mL amp — but you give it intramuscularly into the lateral thigh (vastus lateralis), not IV. The adult dose is 0.3–0.5 mg IM, repeated every 5–15 minutes as needed. IM into the thigh gives fast, reliable absorption with far less arrhythmia risk than an IV bolus. Only in refractory anaphylaxis with shock does epinephrine move to a carefully titrated IV infusion, and by then you want continuous monitoring and ideally a central line.

Infusion dosing for shock

As a continuous infusion, epinephrine is used in cardiogenic shock, refractory septic shock (often as a second- or third-line agent), and post-arrest hemodynamic support. Typical ranges run about 0.01–0.5 mcg/kg/min, titrated to a MAP goal and perfusion. At the low end you get mostly inotropy and chronotropy; as you climb, vasoconstriction dominates. It runs through a central line whenever possible because of the extravasation and tissue-injury risk that comes with any potent vasopressor.

Push-dose epinephrine

Push-dose (or "bolus-dose") pressor is a bridge for transient, severe hypotension — peri-intubation, a brief post-induction drop, or while a drip is being mixed. A common bedside preparation takes 1 mL of the 0.1 mg/mL cardiac syringe (100 mcg) into a 10 mL flush to make 10 mcg/mL, then gives 0.5–2 mL (5–20 mcg) every 2–5 minutes. Onset is about a minute, duration 5–10 minutes. Push-dose is powerful and error-prone: label it, know your concentration, and treat it as a short bridge, not a substitute for a titrated drip.

The side effects and cautions that matter

Tachyarrhythmias. Beta stimulation can trigger sinus tachycardia, atrial and ventricular ectopy, and dangerous arrhythmias, especially at higher doses.

Myocardial ischemia. Increased heart rate and contractility raise oxygen demand — a real concern in coronary disease.

Hyperglycemia and lactate rise. Epinephrine drives glycogenolysis and can raise lactate through beta-2 effects; a lactate bump on an epi drip is not automatically worsening perfusion.

Extravasation. As a potent vasoconstrictor, a peripheral infiltration can cause tissue ischemia; phentolamine is the classic antidote.

Hypertension. Excess alpha effect or a dosing error can spike blood pressure sharply.

Bottom line

Epinephrine is the Swiss-army drug of critical care: a code-cart lifesaver, an anaphylaxis rescue, and a titratable inotrope-pressor all in one molecule. What makes it safe is not memorizing a single number but knowing which concentration and route each job demands — 0.1 mg/mL IV for arrest, 1 mg/mL IM for anaphylaxis, a dilute drip for shock, and a labeled 10 mcg/mL for push-dose. Respect the arrhythmia and ischemia risks, watch the monitor, and confirm the concentration every single time.

This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols, pharmacy guidance, or a provider's orders. Always follow facility policy and verify doses independently.