How the max dose is calculated
Lidocaine's safe upper limit is a weight-based mg/kg figure, capped at an absolute maximum regardless of weight. Adding epinephrine causes local vasoconstriction, which slows systemic absorption and allows a higher total dose to be used safely — this is why the with-epinephrine maximum is meaningfully higher than plain lidocaine.
Maximum dose by formulation
| Formulation | Max dose | Absolute cap |
|---|---|---|
| Plain (no epinephrine) | 4.5 mg/kg | 300 mg |
| With epinephrine | 7 mg/kg | 500 mg |
Clinical use
- The calculated maximum applies to the total dose given across all injection sites during a single procedure, not per site — track cumulative volume when infiltrating multiple areas.
- Epinephrine-containing lidocaine should generally be avoided in end-arterial fields (fingers, toes, nose tip, ear, penis) due to the theoretical risk of vasospasm-related ischaemia, despite this being a lower risk in practice than classically taught.
- In children, hepatically-impaired patients, or those on interacting medications (e.g. amiodarone, other Class Ib antiarrhythmics), consider using a more conservative dose below the calculated maximum.
- Onset is typically within a few minutes for infiltration, with a duration of roughly 1-2 hours (longer with epinephrine).
Frequently asked questions
What is the maximum safe dose of lidocaine?
4.5 mg/kg (up to an absolute maximum of 300 mg) without epinephrine, or 7 mg/kg (up to 500 mg) with epinephrine — whichever is lower for the patient's weight.
Why can you give more lidocaine with epinephrine?
Epinephrine causes local vasoconstriction at the injection site, slowing systemic absorption of the lidocaine into the bloodstream — this reduces peak blood levels for a given dose, allowing a higher total amount to be used safely.
What are the signs of lidocaine toxicity?
Early signs include perioral numbness/tingling, a metallic taste, tinnitus, and light-headedness. More severe toxicity can progress to slurred speech, visual disturbance, seizures, and — at high levels — cardiac arrhythmia and cardiac arrest (local anaesthetic systemic toxicity, or LAST).
Is lidocaine with epinephrine safe on fingers and toes?
Modern evidence suggests it's safer than classically taught, but many clinicians still avoid it in end-arterial fields (digits, nose, ears, penis) as a precaution against theoretical vasospasm-related ischaemia — follow local protocol.
References
- Neal JM, et al. American Society of Regional Anesthesia and Pain Medicine Checklist for Managing Local Anesthetic Systemic Toxicity. Reg Anesth Pain Med. 2018.
- British National Formulary (BNF) — Lidocaine hydrochloride, local anaesthesia.