Bedside Snapshot
  • Core dose: 6 mg rapid IV push → 12 mg → 12 mg (if needed); reduce to 3 mg if given via central line
  • Onset/duration: Immediate onset (within seconds); half-life <10 seconds; effects last <1 minute
  • Key danger: Causes brief asystole (expected, 3–15 seconds); can trigger severe bronchospasm in asthma/COPD. For wide-QRS tachycardia, consider adenosine only if the patient is stable and the rhythm is regular and monomorphic; unstable patients need immediate synchronized cardioversion, and uncertain or non-conforming rhythms should be treated as ventricular tachycardia per your local protocol
  • Special: Must give as rapid IV push over 1–3 seconds followed immediately by 20 mL saline flush; use large proximal vein (antecubital preferred); warn patient of flushing, chest pressure, and dyspnea; record continuous rhythm strip
Brand & Generic Names
  • Generic Name: Adenosine
  • Brand Names: Adenocard, Adenoscan
Medication Class

Antiarrhythmic (unclassified), endogenous nucleoside

Pharmacology

Mechanism of Action:

  • Slows conduction through the AV node by activating adenosine A1 receptors
  • Interrupts reentry pathways through the AV node, terminating supraventricular tachycardias (SVT)
  • Causes transient AV nodal block, allowing restoration of normal sinus rhythm
  • Does not affect atrial or ventricular tissue directly

Pharmacokinetics:

  • Onset: Immediate (within seconds)
  • Duration: Less than 10 seconds (half-life <10 sec)
  • Metabolism: Rapidly metabolized by adenosine deaminase in red blood cells and vascular endothelium
  • Elimination: Metabolites excreted renally
Indications
  • Primary indication: First-line treatment for stable, narrow-complex supraventricular tachycardia (SVT) in hemodynamically stable patients
  • Paroxysmal supraventricular tachycardia (PSVT)
  • AV nodal reentrant tachycardia (AVNRT)
  • AV reentrant tachycardia (AVRT) associated with Wolff-Parkinson-White (WPW) syndrome when narrow-complex
  • Diagnostic aid: in stable wide-QRS tachycardia that is regular and monomorphic, the transient AV nodal block can unmask underlying atrial activity and help differentiate SVT from ventricular tachycardia (VT), per the AHA 2025 adult tachycardia algorithm
Conditions Treated
  • Supraventricular tachycardia (SVT)
  • Paroxysmal supraventricular tachycardia (PSVT)
  • AV nodal reentrant tachycardia (AVNRT)
  • AV reentrant tachycardia (AVRT)
  • Wolff-Parkinson-White syndrome (narrow-complex tachycardia only)
Dosing & Administration

Available Forms:

  • Injectable solution: 3 mg/mL in 2 mL and 4 mL vials (6 mg and 12 mg)

Dosing:

Patient Population Initial Dose Second Dose (if needed) Third Dose (if needed)
Adults 6 mg rapid IV push 12 mg rapid IV push 12 mg rapid IV push
Pediatrics 0.1 mg/kg (max 6 mg) rapid IV push 0.2 mg/kg (max 12 mg) rapid IV push 0.2 mg/kg (max 12 mg) rapid IV push
Administration Technique: Administer as rapid IV/IO push over 1-3 seconds followed immediately by 20 mL saline flush. Use large proximal vein (antecubital) for best results. Elevate arm after administration.
Contraindications

Absolute Contraindications:

  • Second- or third-degree AV block (unless patient has a functioning pacemaker)
  • Sick sinus syndrome (unless patient has a functioning pacemaker)
  • Known hypersensitivity to adenosine
  • Atrial fibrillation or atrial flutter with accessory pathway (e.g., WPW with wide-complex tachycardia)
  • Bronchospastic lung disease (e.g., asthma, COPD with active bronchospasm) - relative contraindication
Warning - Wide-QRS tachycardia: Per the AHA 2025 adult tachycardia algorithm, adenosine may be considered for stable wide-QRS tachycardia only if the rhythm is regular and monomorphic. If the patient is unstable, go directly to synchronized cardioversion. Do not give adenosine if the rhythm is irregular, polymorphic, or pre-excited atrial fibrillation (e.g., WPW with atrial fibrillation); treat those rhythms as ventricular tachycardia and follow your local VT protocol (antiarrhythmic infusion or synchronized cardioversion). When the diagnosis is uncertain, treat any wide-complex tachycardia as ventricular tachycardia.

Precautions:

  • Use with caution in patients on dipyridamole (Persantine) or carbamazepine - smaller doses may be needed
  • Patients on theophylline or caffeine may require higher doses
  • May cause transient severe bradycardia, asystole, or other dysrhythmias
Adverse Effects

Common (usually brief, lasting <1 minute):

  • Facial flushing (very common, almost universal)
  • Dyspnea or sense of chest tightness
  • Transient bradycardia or asystole (typically 3-5 seconds, can be up to 15 seconds)
  • Chest discomfort or pressure
  • Headache
  • Lightheadedness or dizziness
  • Nausea
  • Metallic taste

Serious (rare):

  • Prolonged asystole (rarely >15 seconds)
  • Ventricular fibrillation or ventricular tachycardia
  • Atrial fibrillation (transient)
  • Bronchospasm (especially in patients with asthma or COPD)
  • Severe hypotension
  • Seizures (very rare)
Patient Communication: Warn the patient before administration that they will feel flushing, chest pressure, and dyspnea for a few seconds. This significantly reduces anxiety.
Clinical Pearls
The "Push-Flush-Push" Technique: Adenosine has an extremely short half-life (<10 seconds). To maximize effectiveness, use the largest, most proximal IV site available (antecubital preferred). Push adenosine rapidly over 1-3 seconds, immediately follow with 20 mL saline flush pushed just as rapidly, and elevate the extremity. This ensures the medication reaches the heart before it's metabolized.
Expect Brief Asystole: Adenosine will often cause 3-15 seconds of asystole on the monitor. This is expected and therapeutic. Warn your patient, prepare your team, and have resuscitation equipment ready. The pause is what allows the sinus node to "reset" and restore normal rhythm.
Capture the Rhythm: Always print or record a continuous rhythm strip during adenosine administration. If the SVT doesn't convert, the brief pause may reveal underlying atrial activity (flutter waves, fibrillation) that can aid in diagnosis.
Drug Interactions: Theophylline and caffeine antagonize adenosine's effects (may need higher doses). Dipyridamole and carbamazepine potentiate adenosine's effects (use smaller doses, consider 3 mg initial dose).
Wide vs. Narrow: Adenosine is first-line for stable, regular narrow-complex SVT. For wide-QRS tachycardia, the AHA 2025 adult tachycardia algorithm allows considering adenosine only when the patient is stable and the rhythm is regular and monomorphic. Do not give adenosine if the rhythm is irregular, polymorphic, or pre-excited atrial fibrillation. Unstable patients should go directly to synchronized cardioversion. If the diagnosis is uncertain, treat the rhythm as ventricular tachycardia and follow your local VT protocol.
Success Rate: Adenosine successfully converts 90-95% of reentrant SVTs (AVNRT, AVRT). If it doesn't work after 3 doses, the rhythm is likely something else (atrial flutter, atrial fibrillation, or VT).
Asthma/COPD Caution: Use extreme caution or avoid in patients with active bronchospasm. Adenosine can trigger severe, life-threatening bronchospasm in asthmatics. If you must use it, have epinephrine and albuterol ready.
Central Line Dosing: If administered via central line, reduce initial dose to 3 mg for adults due to faster delivery to the heart.
Sources & Updates
  • 1. American Heart Association. (2025). Adult tachycardia with a pulse algorithm. In 2025 AHA Guidelines for CPR and ECC. https://cpr.heart.org/-/media/CPR-Files/CPR-Guidelines-Files/2025-Algorithms/Algorithm-ACLS-Tachycardia-250514.pdf?sc_lang=en

Guideline wording updated September 14, 2026 to align the wide-QRS language on this page with the AHA 2025 adult tachycardia algorithm: consider adenosine for stable wide-QRS tachycardia only if the rhythm is regular and monomorphic, send unstable patients to synchronized cardioversion, and do not give adenosine for irregular, polymorphic, or pre-excited rhythms. This note covers wording alignment only; no named clinician review is claimed. Always follow your local protocols and institutional guidelines.

Spotted something wrong on this page? Report an error and include the page URL and the topic so we can check it against the source.

Back to Medication Index
Medical Disclaimer
  • For Educational Purposes Only: This content is intended for educational reference and should not be used for clinical decision-making.
  • Not a Substitute for Professional Judgment: Always consult your local protocols, institutional guidelines, and supervising physicians.
  • Verify Before Acting: Users are responsible for verifying information through authoritative sources before any clinical application.
AI Assistance Notice
AI was used to assist in organizing and formatting this information.