Nursing care
Vasopressors: what to check before you give it
Written and reviewed by Dana Whitfield, RN, MSN · 5 min read · Updated September 2026
Short answer
Vasopressors raise blood pressure by constricting blood vessels or increasing cardiac contractility, and they are given continuously by infusion pump through a central line whenever possible. Because extravasation causes tissue necrosis, the IV site is checked more often than the blood pressure reading itself, since a leaking peripheral line can cause irreversible damage before the next scheduled vital sign.
Mechanism, simply
Vasopressors act on adrenergic receptors to raise blood pressure, either by constricting peripheral blood vessels, increasing heart rate and contractility, or both. Norepinephrine acts predominantly on alpha-1 receptors, producing strong vasoconstriction with a modest beta-1 effect on the heart. Dopamine's effect is dose-dependent, moving from dopaminergic receptor activity at low doses to beta-1 and then alpha-1 dominance as the dose climbs, which is why its clinical behaviour changes across its dose range in a way norepinephrine's does not.
Epinephrine and vasopressin work through different pathways again, epinephrine through combined alpha and beta stimulation and vasopressin through V1 receptors independent of the adrenergic system entirely. Knowing which receptor a given drug favours tells you what side effect to expect first.
Indications you will see on the ward
Norepinephrine is first-line for septic shock and is the vasopressor most nurses will titrate most often in the ICU. Dopamine has fallen out of first-line use for shock generally but still appears for symptomatic bradycardia unresponsive to atropine. Epinephrine is used in anaphylaxis and cardiac arrest, and as a second agent in septic shock when norepinephrine alone is not achieving target pressure.
Vasopressin is typically added as a second-line agent in septic shock to allow the norepinephrine dose to be reduced, and it is also used in cardiac arrest protocols. These drugs are almost always run through a dedicated central line in a critical care or step-down setting, with continuous arterial line or non-invasive blood pressure monitoring and an infusion pump capable of precise micro-dosing.
Assessment before administration
Confirm IV access before anything else. A central line is preferred for any vasopressor infusion expected to run more than a short period, because peripheral administration carries meaningful extravasation risk. If a peripheral line must be used temporarily, choose a large proximal vein, document it clearly, and plan for central access as soon as possible.
Get a baseline blood pressure, heart rate, and perfusion assessment, capillary refill, skin temperature, urine output, and mental status, before starting the infusion so you have something to titrate against. Check the current line for patency and a good blood return; do not start a vasopressor through a line you are not confident is intact. Review the patient's cardiac history, since these drugs increase myocardial oxygen demand and can provoke arrhythmia or ischemia in a vulnerable heart.
Toxicity and the antidote
Overdose or excessive titration produces severe hypertension, reflex bradycardia, arrhythmia, and in extreme cases myocardial ischemia or intracranial haemorrhage from the pressure spike. Management is to stop or reduce the infusion immediately and treat the hypertension per protocol; there is no drug antidote for systemic vasopressor overdose, so the intervention is dose reduction and haemodynamic support.
The more common toxicity a nurse will actually manage is local: extravasation into subcutaneous tissue. Because these drugs cause profound vasoconstriction at the injection site, leaked drug can cut off blood supply to the surrounding tissue and cause necrosis within hours. The specific antidote for extravasation is phentolamine, an alpha-adrenergic blocker, injected locally around the infiltrated area to reverse the vasoconstriction and preserve the tissue. This is why the IV site is assessed on a schedule that is often tighter than the vital sign interval, and why any new swelling, blanching, or pain at the site is treated as an emergency, not a note for later.
Interactions that matter
Combining vasopressors with MAOIs or tricyclic antidepressants can produce an exaggerated hypertensive response, since these drugs interfere with the normal breakdown or reuptake of catecholamines. Beta-blockers blunt the cardiac effects of dopamine and epinephrine, which can leave alpha-mediated vasoconstriction unopposed and raise blood pressure further while doing little for heart rate.
Vasopressors should not be run through the same line as sodium bicarbonate or other alkaline solutions, since alkaline pH inactivates catecholamines. Concurrent use of other vasoactive drugs, or volume status that has not been corrected first, changes how a patient responds to a given dose, so fluid resuscitation status is always part of the picture before you interpret a blood pressure trend as a vasopressor effect.
What the patient must be told
Patients receiving vasopressors are typically too acutely unwell for extensive teaching, so most communication is with family and focuses on what the infusion is doing and why the dose changes frequently. Explain that the medication is being adjusted continuously to keep blood pressure in a safe range and that changes in the rate reflect how the patient's own body is responding, not a sign of instability by itself.
If the patient is alert, tell them to report any burning, stinging, or new pain at the IV site immediately, since this can be the first sign of a problem with the line before it is visible. As the patient recovers and the infusion is weaned, explain that a drop in blood pressure during weaning is expected and monitored closely, and that the team titrates slowly for that reason.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our pharmacology practice questions are the closest set to what this page covers.
One question from the pharmacology set
A client with heart failure is started on furosemide 40 mg PO daily. Which findings should the nurse report to the provider before administering the next dose? Select all that apply.
Rationale
Furosemide is a loop diuretic, so the two things you are watching are potassium and kidney function. A potassium of 2.9 mEq/L is below the 3.5–5.0 reference range and puts the client at risk for dysrhythmia — hold and report. Muscle cramps with palpitations are the clinical face of that same hypokalemia, so they are reported together, not separately. A creatinine that doubles signals the diuresis has outrun renal perfusion. A blood pressure of 132/78 and a 1 kg loss are the expected response to the drug working, not reasons to hold it.
Answer: A, D, E
Common questions
Why is the IV site checked more often than blood pressure during a vasopressor infusion?
Vasopressors cause intense local vasoconstriction, so if the line infiltrates, the leaked drug can cut off blood supply to the surrounding tissue and cause necrosis within hours. Blood pressure trends slowly enough to catch on a routine schedule, but extravasation damage can begin before the next scheduled reading.
What is the antidote for vasopressor extravasation?
Phentolamine, an alpha-adrenergic blocker, is injected locally around the infiltrated site to reverse the vasoconstriction and prevent tissue necrosis. It must be given promptly once extravasation is recognised.
Why is norepinephrine preferred over dopamine for septic shock?
Norepinephrine causes fewer arrhythmias and is associated with lower mortality in septic shock compared with dopamine, which carries a higher risk of tachyarrhythmia. Dopamine is now reserved mainly for selected bradycardia cases.
Can a vasopressor be given through a peripheral IV?
It can be done short-term with a large proximal vein and close monitoring, but a central line is preferred for any infusion expected to run for more than a brief period, because the extravasation risk with peripheral access is significant.
Why does vasopressin get added to norepinephrine instead of replacing it?
Vasopressin acts on a separate receptor pathway, so adding it allows the norepinephrine dose to be reduced without losing pressure control, which lowers the catecholamine burden on the heart.
More on pharmacology
Guides on this