Epinephrine
Levo-epinephrine
Also known as: EpiPen · Twinject · Adrenaline · Epinephrine HCl · Epinephrine bitartrate · Levo-epinephrine · Epinephrinum · L-epinephrine
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Reviewed non-calculator evidenceReviewed non-calculator evidence (2)
Evidence only — not for automatic calculation
Most species/CPR, cardiac arrest
TABLE 127.5. Agent: Epinephrine (1 : 1000). Dosage: 0.5–1 mg/kg IV, IO, IT232. Species/Comments: Most species/CPR, cardiac arrest.
Evidence only — not for automatic calculation
Snapping turtles/reduction in time to spontaneous respiration after isoflurane anesthesia
TABLE 127.5. Agent: Epinephrine (1 : 1000). Dosage: 0.1 mg/kg IM106. Species/Comments: Snapping turtles/reduction in time to spontaneous respiration after isoflurane anesthesia.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Epinephrine (commonly known as adrenaline) is a potent, endogenous catecholamine produced by the adrenal medulla. It is the primary "fight or flight" hormone of the sympathetic nervous system.
In veterinary medicine, it is a critical, life-saving emergency drug used primarily for:
- Cardiopulmonary Cerebral Resuscitation (CPCR): To restore spontaneous circulation during cardiac arrest (asystole).
- Severe Anaphylaxis: To rapidly reverse life-threatening allergic reactions by inducing bronchodilation and vasoconstriction.
- Local Anesthesia Adjunct: Added to local anesthetics (like lidocaine) to induce local vasoconstriction, thereby delaying systemic absorption, prolonging the anesthetic effect, and reducing bleeding at the site.
Clinical Pearl: Epinephrine is highly potent and has a very narrow therapeutic index. Extreme care must be taken to ensure the correct concentration is used. Never confuse the 1:1,000 (1 mg/mL) concentration with the 1:10,000 (0.1 mg/mL) concentration.
Mechanism of action
Epinephrine is a direct-acting, non-selective adrenergic agonist that stimulates both alpha (α) and beta (β) receptors via G-protein coupled pathways (activating adenylyl cyclase → ↑ cAMP).
- α1-receptors: → Induces profound smooth muscle contraction and vasoconstriction, increasing systemic vascular resistance and blood pressure.
- β1-receptors: → Directly stimulates the heart, increasing both chronotropy (heart rate) and inotropy (contractility), which increases cardiac output and myocardial oxygen demand.
- β2-receptors: → Relaxes smooth muscle, leading to profound bronchodilation (relieving bronchospasm in anaphylaxis), vasodilation in skeletal muscle, and increased glycogenolysis (raising blood sugar).
- Histamine Antagonism: Physiologically antagonizes the effects of histamine released during anaphylaxis.
Hemodynamic effects depend on the route and rate of administration: Rapid IV injection causes direct cardiac stimulation and increased systolic BP. Slow IV infusion produces a modest rise in systolic pressure, a decrease in diastolic pressure, and decreased total peripheral resistance due to dominant β2 effects.
Safety & warnings
Contraindications
- Narrow-angle glaucoma
- Hypersensitivity to epinephrine
- Shock due to non-anaphylactoid causes
- During general anesthesia with halogenated hydrocarbons or cyclopropane
- During labor (may delay the second stage)
- Cardiac dilatation or coronary insufficiency
- Conditions where vasopressors are contraindicated (e.g., thyrotoxicosis, diabetes, hypertension, toxemia of pregnancy)
- Injection with local anesthetics into small appendages (toes, ears, etc.) due to risk of necrosis
Adverse effects
- Anxiety and fear
- Tremors and excitability
- Vomiting
- Hypertension (especially with overdosage)
- Cardiac arrhythmias (especially with pre-existing heart disease)
- Hyperuricemia
- Lactic acidosis (with prolonged use or overdose)
- Tissue necrosis and sloughing at the injection site (with repeated injections or injection into small appendages)
Precautions
Hypovolemia: Epinephrine is not a substitute for adequate fluid volume replacement therapy. Cardiac Rhythms: Use with extreme caution in patients with a prefibrillatory cardiac rhythm due to excitatory effects on the heart. While useful in asystole, it can cause ventricular fibrillation; use cautiously in cases of existing ventricular fibrillation. Tissue Necrosis: Do not inject into small appendages (ears, toes, tails) as profound vasoconstriction can cause ischemic necrosis and sloughing. Concentration Errors: Always double-check the concentration (1:1,000 vs 1:10,000) before administration to avoid fatal overdoses.
Drug interactions
May negate the therapeutic effects of epinephrine.
Do NOT use epinephrine to treat cardiac effects caused by alpha-2 agonists; may worsen hemodynamics.
Increased risk of developing severe arrhythmias. Propranolol may be used to treat if they occur.
May potentiate the effects of epinephrine.
May potentiate hypertension and antagonize epinephrine's cardiac and bronchodilating effects.
Increased risk of arrhythmias if used concurrently.
May reverse the pressor effects of epinephrine.
May potentiate the effects of epinephrine.
Hypertension may result if used concurrently.
Should not be administered together as increased toxicity may result.
May reverse the pressor effects of epinephrine.
May potentiate the pressor effects of epinephrine.
May potentiate the effects of epinephrine.
Additive effects leading to potential toxicity
May potentiate the effects of adrenaline
May potentiate the effects of adrenaline
May block the beta effects of adrenaline, facilitating an increase in blood pressure
May negate or diminish the pressor effects of adrenaline
May negate or diminish the pressor effects of adrenaline
Sensitizes the myocardium, increasing the risk of arrhythmias
Sensitizes the myocardium, increasing the risk of arrhythmias
Sensitizes the myocardium to catecholamines, increasing the risk of severe ventricular arrhythmias.
Antagonizes the beta-adrenergic effects of epinephrine, leaving unopposed alpha-adrenergic vasoconstriction which can lead to severe hypertension.
May potentiate the cardiovascular effects of epinephrine.
May reverse the pressor effects of epinephrine, potentially leading to vasodilation and hypotension (epinephrine reversal).
Monitoring
- Cardiac rate and rhythm (ECG)
- Respiratory rate and auscultation (especially during anaphylaxis)
- Urine flow (if possible)
- Blood pressure
- Blood gases (if indicated and possible)
Pharmacokinetics
Absorption
Well-absorbed following IM or SC administration. IM injections are slightly faster absorbed than SC; massaging the site expedites absorption. Rapidly metabolized in the GI tract and liver after oral administration (not effective PO). SC onset of action is 5-10 minutes. IV onset is immediate.
Distribution
Does not cross the blood-brain barrier. Crosses the placenta and is distributed into milk.
Metabolism
Actions are ended primarily by uptake and metabolism into sympathetic nerve endings. Metabolized in the liver and other tissues by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) to inactive metabolites.
Elimination
Excreted as inactive metabolites.
Overdose
Clinical signs of overdosage or inadvertent IV administration of SC/IM doses include:
- Sharp rises in systolic, diastolic, and venous blood pressures
- Cardiac arrhythmias
- Pulmonary edema and dyspnea
- Vomiting, headache, and chest pain
- Cerebral hemorrhages (due to severe hypertension)
- Renal failure, metabolic acidosis, and cold skin
Treatment: Because epinephrine has a relatively short duration of effect, treatment is mainly supportive. If necessary, an alpha-adrenergic blocker (e.g., phentolamine) or a beta-adrenergic blocker (e.g., propranolol) can be used to treat severe hypertension and cardiac arrhythmias. Prolonged periods of hypotension may follow, requiring treatment with norepinephrine.
Available products
Formulations
- Injection solution (1:1,000 / 1 mg/mL)
- Injection solution (1:10,000 / 0.1 mg/mL)
- Auto-injectors (0.15 mg, 0.3 mg)
- Aerosol for inhalation
- Topical solution
- Solution for nebulization
- Ophthalmic preparations
Veterinary
- Epinephrine HCl for Injection 1 mg/mL (1:1,000) in 1 mL amps/syringes and 10 mL, 30 mL, 100 mL vials (Amtech, Am-Vet, Vedco, Vetus, AgriPharm, Durvet, Bimeda, etc.)
Human-labeled
- Epinephrine HCl Solution for Injection: 1 mg/mL (1:1,000) in amps and vials (Adrenalin Chloride)
- Epinephrine HCl Solution for Injection auto-injectors: 1:1,000 (0.3 mg) (EpiPen, Twinject)
- Epinephrine HCl Solution for Injection auto-injectors: 1:2,000 (0.15 mg) (EpiPen Jr)
- Epinephrine HCl Solution for Injection: 1:10,000 (0.1 mg/mL) in syringes and vials
- Epinephrine bitartrate powder (aerosol) for inhalation
- Topical solutions
- Ophthalmic preparations
Regulatory status
Withdrawal times: cattle meat 0 days · cattle milk 0 days
Commonly referred to as Adrenaline in EU regulatory documents.
Withdrawal times: cattle meat 0 days · cattle milk 0 days
Commonly referred to as Adrenaline.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store in tight containers protected from light. Epinephrine will darken (oxidize) upon exposure to light and air. Do not use if the injection is pink, brown, or contains a precipitate. Rapidly destroyed by alkalies or oxidizing agents.
Client information
Epinephrine is a life-saving emergency medication used for severe allergic reactions (anaphylaxis).
- Emergency Use Only: If you have been prescribed pre-loaded syringes (like an EpiPen) for your pet, use it only for known, severe allergic reactions as directed by your veterinarian.
- Seek Immediate Care: Even after administering epinephrine, you must take your pet to a veterinary emergency clinic immediately. The drug wears off quickly, and the allergic reaction may return.
- Administration: Ensure you understand the proper injection technique (usually into the muscle or under the skin) demonstrated by your vet.
- Storage: Store at room temperature away from light. Do not use the medication if it is past its expiration date, if the liquid has turned pink or brown, or if you see particles floating in it.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.