Lidocaine
Lidocaine hydrochloride
Also known as: Xylocaine MPF · EMLA · Intubeaze · Lignadrin · Lignol · Locovetic · Lidoderm · lidocaini hydrochloridum · lignocaine hydrochloride · Lidocainum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidenceRegional anesthesia (extra-label) — CRI via peritoneal wound catheter
Verified clinician required
NA
Governing clinical context (5)
- 1. Lidocaine formulation concentration, administration volume, site of administration, administration technique (eg, aspiration prior to injection), and underlying patient condition(s) are important interrelated factors that determine lidocaine’s safe and effective use.
- 2. All dosages below use 2% lidocaine (20 mg/mL) unless otherwise specified.
- Infiltration: dilute to 0.5% concentration (for each 1 mL of lidocaine 2% solution, dilute with 3 mL sterile water)
- Regional anesthesia (extra-label):
- Lidocaine should be stored at room temperature, at 15°C to 30°C (59°F-86°F).
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Lidocaine is a versatile amide-class local anesthetic and Class IB antiarrhythmic agent. In veterinary medicine, it is widely utilized not only for local/regional anesthesia but also systemically for the management of ventricular arrhythmias, neuropathic pain, and gastrointestinal motility disorders.
Key clinical applications include:
- Antiarrhythmic Therapy: The drug of choice for acute, life-threatening ventricular tachycardia (VT) and ventricular premature complexes (VPCs) in dogs.
- Systemic Analgesia: Administered as a constant rate infusion (CRI), often in combination with opioids and ketamine (e.g., MLK CRI), to provide profound adjunctive analgesia, reduce MAC (minimum alveolar concentration) of inhalant anesthetics, and mitigate neuropathic pain or hyperalgesia.
- Prokinetic & Anti-inflammatory Effects: In horses, systemic lidocaine is frequently used to treat or prevent postoperative ileus and to scavenge reactive oxygen species (ROS), thereby reducing reperfusion injury.
Clinical Pearl: Cats are significantly more sensitive to the cardiodepressant and central nervous system (CNS) toxic effects of lidocaine. Its systemic use in felines remains controversial and requires extreme caution and precise dosing.
Mechanism of action
Lidocaine exerts its effects through multiple mechanisms depending on the target tissue:
- Antiarrhythmic Action (Class IB): Lidocaine binds to and blocks fast voltage-gated sodium channels (Nav1.5) in the myocardium. It exhibits use-dependent and state-dependent blockade, meaning it preferentially binds to sodium channels in their inactive state (which occurs during depolarization). This action → attenuates phase 4 diastolic depolarization → decreases automaticity → suppresses ectopic ventricular pacemakers without significantly affecting the SA or AV nodes at therapeutic levels.
- Local Anesthetic/Analgesic Action: Blocks neuronal voltage-gated sodium channels, preventing the influx of sodium required for the initiation and conduction of action potentials in peripheral nerves. Systemically, it reduces ectopic firing from damaged afferent neurons, providing relief from neuropathic pain.
- Prokinetic & Cytoprotective Action: The exact mechanism for enhancing intestinal motility (especially in equine ileus) is multifactorial, likely involving suppression of sympathetic inhibitory reflexes, direct anti-inflammatory effects, and acting as a scavenger of reactive oxygen species (ROS) to prevent lipid peroxidation and reperfusion injury.
Safety & warnings
Contraindications
- Known hypersensitivity to amide-class local anesthetics
- Severe SA, AV, or intraventricular heart block (unless artificially paced)
- Adams-Stokes syndrome
- Intravenous use of lidocaine products containing epinephrine
- Continuous rate infusion (CRI) in cats during the perioperative period (due to negative haemodynamic effects)
- Intravenous administration of lidocaine solutions containing adrenaline
- Use of adrenaline-containing solutions for complete ring block of an extremity (danger of ischaemic necrosis)
Adverse effects
- CNS toxicity (dose-related): drowsiness, depression, ataxia, nystagmus, muscle tremors, seizures
- Gastrointestinal: nausea and vomiting (usually transient)
- Cardiovascular: hypotension (especially with rapid IV bolus), bradycardia, PR and QRS interval prolongation, circulatory collapse at toxic doses
- Cats: heightened risk of severe cardiodepression and CNS signs
- Muscle fasciculations
- Laryngeal oedema (in cats, associated with CFC propellants in unlicensed aerosols)
Precautions
Use with extreme caution in cats due to heightened sensitivity to CNS and cardiodepressant effects. Use cautiously in patients with liver disease, congestive heart failure, shock, hypovolemia, severe respiratory depression, or marked hypoxia. Patients susceptible to malignant hyperthermia require intensified monitoring. NEVER administer lidocaine containing epinephrine intravenously.
Drug interactions
Lidocaine infusions reduce MAC requirements. Additive cardiodepression may occur, especially in cats.
May cause additive or antagonistic cardiac effects; enhanced risk of toxicity.
May decrease lidocaine clearance, increasing lidocaine levels and effects.
Diuretic-induced hypokalemia may reduce the antiarrhythmic efficacy of lidocaine.
May induce hepatic enzymes, increasing lidocaine metabolism and decreasing its serum levels.
May decrease hepatic blood flow and lidocaine clearance, increasing lidocaine levels.
Large doses of lidocaine may prolong succinylcholine-induced apnea.
May cause increased myocardial depression
Monitoring
- Continuous ECG monitoring (especially during IV bolus or CRI)
- Signs of CNS toxicity (ataxia, tremors, seizures)
- Blood pressure (monitor for hypotension)
- Serum lidocaine levels if available (Therapeutic range: 1-6 micrograms/mL)
- ECG (especially during IV therapy for arrhythmias)
- Heart rate
- CNS signs (monitor for fasciculations or seizures)
Pharmacokinetics
Half-life
Absorption
High first-pass effect makes it ineffective orally. Following a therapeutic IV bolus, onset of action is generally within 2 minutes with a duration of 10-20 minutes.
Distribution
Rapidly redistributed from plasma into highly perfused organs (kidney, liver, lungs, heart), then widely throughout body tissues. High affinity for fat and adipose tissue. Bound to plasma proteins (primarily alpha1-acid glycoprotein). Vd is approximately 4.5 L/kg in dogs.
Metabolism
Rapidly metabolized in the liver to active metabolites (MEGX and GX).
Elimination
Less than 10% of a parenteral dose is excreted unchanged in the urine.
Overdose
In dogs, toxicity may result if serum levels exceed 8 micrograms/mL.
- Clinical Signs: Ataxia, nystagmus, depression, seizures, bradycardia, hypotension, and at very high levels, circulatory collapse.
- Management: Because lidocaine is rapidly metabolized, simply stopping the infusion or reducing the rate (with close monitoring) is often sufficient for minor signs.
- Seizure Control: Treat seizures or excitement with diazepam or a short/ultrashort-acting barbiturate. > Warning: Longer-acting barbiturates (e.g., pentobarbital) should be avoided.
- Cardiovascular Support: Treat circulatory depression with IV fluids, pressor agents, and initiate CPR if necessary.
Available products
Formulations
- Injection: 0.5%, 1%, 1.5%, 2%, 4% solutions
- Premixed IV infusion solutions (with D5W)
- Topical: patches, ointments, creams, lotions, gels, sprays, and jellies
- Injectable: 1% solution
- Injectable: 2% solution (some contain adrenaline)
- Topical: 2% solution
- Topical: 4% solution
- Topical: 2.5% cream (with prilocaine)
- Transdermal: 5% patches
Veterinary
- Lidocaine HCl for Injection: 2% (20 mg/mL) in 100 mL & 250 mL multi-use vials
- Intubeaze 2% topical solution
- Lignadrin injectable
- Lignol injectable
- Locaine injectable
- Locovetic injectable
Human-labeled
- Lidocaine Hydrochloride Injection: 0.5%, 1%, 1.5%, 2% & 4% in various vials, ampules, and syringes
- Lidocaine Hydrochloride with Dextrose Injection: 1.5% or 5% with 7.5% dextrose
- Premixed IV infusions in D5W (2 mg/mL, 4 mg/mL, 5 mg/mL)
- Topical liquids, patches, ointments, creams, lotions, gels, sprays, and jellies
- EMLA 2.5% cream (with prilocaine)
- Xylocaine 4% topical solution
- Lidoderm 5% transdermal patch
Regulatory status
POM-V classification
POM-V classification
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at temperatures less than 40°C, preferably between 15-30°C. Avoid freezing.
Client information
Lidocaine is a potent medication used primarily in the hospital setting by veterinary professionals.
- Purpose: It is used to correct life-threatening abnormal heart rhythms (arrhythmias) or to provide continuous pain relief (often mixed with other pain medications) after major surgery or trauma.
- Monitoring: Because the drug is given directly into the bloodstream, your pet will be closely monitored (usually with an ECG and blood pressure checks) to ensure the dose is safe and effective.
- Side Effects: If side effects occur, they are usually mild and resolve quickly once the medication rate is adjusted. Signs to watch for (if your pet is awake) include sleepiness, muscle tremors, or nausea.
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.