Local Anaesthetic Maximum Doses in Dentistry: A UK Reference

Maximum doses of common UK dental local anaesthetics (quick reference)

The table below lists the five local anaesthetic agents covered by the Nosht calculator, with the maximum dose in mg/kg, the absolute ceiling in mg, the mg of anaesthetic per standard 2.2 ml cartridge, and the adrenaline content where relevant. Verify every value against the current BNF / DPF / SDCEP / SmPC (as of June 2026).

Adrenaline (epinephrine) content per 2.2 ml cartridge — relevant to the cartridge ceiling above and to the cardiovascular cautions, because for the fit adult (and especially the medically compromised patient) the adrenaline load is often the limiting factor, not the anaesthetic mg:

Onset and duration (approximate, for context only) — these are not dose figures but help with agent choice:

Lidocaine 2% with 1:80,000 adrenaline remains the most widely used agent in UK dentistry. Articaine 4% offers good bony diffusion for maxillary infiltration. Prilocaine with felypressin and plain agents are options where adrenaline is to be limited or avoided. Choice of agent, technique and dose is a clinical judgement for the individual patient.

How to calculate the maximum dose (lowest of weight, absolute cap and adrenaline limit)

The maximum dose is the lowest of three limits. This is a method, not a recipe for any individual dose — calculate per patient and verify.

1. Weight-based maximum (mg) = maximum mg/kg for that agent × patient’s weight in kg.
2. Absolute ceiling (mg) — the fixed mg cap for that agent, regardless of weight.
3. Adrenaline (vasoconstrictor) ceiling (mg) — for adrenaline-containing solutions only: the anaesthetic mg that corresponds to the maximum permissible adrenaline. In the Nosht calculator the healthy-adult adrenaline ceiling is 200 micrograms, which for lidocaine 1:80,000 (27.5 µg per cartridge) works out at about 320 mg of lidocaine.

The lowest of the three figures wins. Then confirm against the current BNF / DPF and the individual patient — reduce further for the elderly, the frail, the medically compromised, hepatic or renal impairment, and where adrenaline must be limited (see cautions).

Worked illustration — a 70 kg fit adult (for teaching only). These are the values the Nosht calculator returns:

• Lidocaine 2% with 1:80,000 adrenaline: weight gives 7.0 × 70 = 490 mg, the absolute cap is 500 mg, but the adrenaline ceiling of 200 µg = ~320 mg is the lowest → 320 mg → 320 ÷ 44 = ~7.2 cartridges (adrenaline-limited, not lidocaine-limited).
• Lidocaine 2% plain: 3.0 × 70 = 210 mg, but the 200 mg cap applies → 200 ÷ 44 = ~4.5 cartridges (cap-limited).
• Articaine 4% with 1:100,000 adrenaline: 7.0 × 70 = 490 mg (below the 500 mg cap; adrenaline ceiling ≈ 800 mg does not bite) → 490 ÷ 88 = ~5.5 cartridges (weight-limited).
• Prilocaine 3% with felypressin: 6.0 × 70 = 420 mg, but the 300 mg cap applies → 300 ÷ 66 = ~4.5 cartridges (cap-limited).
• Mepivacaine 3% plain: 4.4 × 70 = 308 mg, but the 300 mg cap applies → 300 ÷ 66 = ~4.5 cartridges (cap-limited).

These illustrative counts are for a fit 70 kg adult with no relevant medical history. They must be reduced for lower body weight, the elderly, the medically compromised, and wherever adrenaline must be limited.

Cartridge maths (mg per cartridge per agent)

A standard UK dental cartridge contains 2.2 ml of solution. The anaesthetic mg in each cartridge is simply the concentration (mg/ml) × 2.2 ml:

• 2% solution = 20 mg/ml → 44 mg per 2.2 ml cartridge (lidocaine).
• 3% solution = 30 mg/ml → 66 mg per 2.2 ml cartridge (prilocaine, mepivacaine).
• 4% solution = 40 mg/ml → 88 mg per 2.2 ml cartridge (articaine).

To convert a maximum mg dose into cartridges: cartridges = maximum mg ÷ mg per cartridge, then round down to stay within the limit. For adrenaline-containing solutions, also check the adrenaline ceiling separately (µg of adrenaline per cartridge × number of cartridges). Confirm the cartridge volume of the specific product you are using — some cartridges are 1.7 ml or 1.8 ml rather than 2.2 ml, which changes the mg per cartridge.

Cautions: cardiovascular disease and adrenaline

The following are summary cautions only and do not replace the current BNF / DPF / SDCEP, the manufacturer SmPC, or assessment of the individual patient. They mirror the traffic-light interaction notes in the Nosht calculator.

• In unstable angina or recent myocardial infarction (within ~6 months) and uncontrolled hypertension (e.g. >180/110), adrenaline-containing solutions warrant caution or avoidance; defer elective care and seek medical advice where appropriate.
• A commonly cited cautious ceiling for adrenaline in cardiac patients is around 0.04 mg (40 µg) per appointment — roughly ~1–2 cartridges of 1:80,000, ~2 cartridges of 1:100,000, or ~3 cartridges of 1:200,000. This is far below the 200 µg healthy-adult ceiling. Where adrenaline must be avoided, consider prilocaine with felypressin or a plain agent.
• Always aspirate before injecting an adrenaline-containing solution to reduce the risk of intravascular administration.

Cautions: drug interactions (adrenaline-related)

• Non-selective beta-blockers (e.g. propranolol): potential for hypertensive response with reflex bradycardia — limit adrenaline (keep total within ~40 µg) and aspirate carefully.
• Tricyclic antidepressants (e.g. amitriptyline): potentiated pressor response to adrenaline — use the minimum effective dose and keep total adrenaline within ~40 µg.
• MAOIs: interaction is unlikely to be clinically significant at dental LA doses (per NHS Specialist Pharmacy Service); use the minimum effective dose; felypressin is an alternative.
• Cocaine use (recent / within ~24 h): adrenaline-containing LA is contraindicated — cocaine potentiates catecholamines (risk of fatal arrhythmia); use a plain agent only.
• Phaeochromocytoma: adrenaline absolutely contraindicated — use plain LA only; hospital setting preferred. Uncontrolled thyrotoxicosis: limit adrenaline (risk of tachycardia/arrhythmia); prefer felypressin or a plain agent.
• Check every patient’s current medication against the current BNF interactions appendix; this list is not exhaustive.

Cautions: methaemoglobinaemia, pregnancy, the medically compromised

Methaemoglobinaemia with prilocaine: prilocaine (and, in overdose, other agents) can cause methaemoglobinaemia. Avoid or use with particular caution in patients with congenital or acquired methaemoglobinaemia, G6PD deficiency, significant anaemia or cardiorespiratory compromise, in neonates/infants, and where the total dose would be high. Monitor for signs at higher doses and consider an alternative agent (lidocaine or articaine).

Pregnancy and breastfeeding: lidocaine with adrenaline is generally regarded as the agent of choice in pregnancy when local anaesthesia is required for necessary dental treatment; articaine is also acceptable, and prilocaine/felypressin is usually avoided (felypressin has theoretical oxytocic activity at high dose; prilocaine carries a foetal methaemoglobinaemia consideration). Confirm the current position for each agent against the BNF/DPF and the patient's obstetric circumstances.

Hepatic and renal impairment, the elderly and the medically compromised: amide local anaesthetics (lidocaine, articaine, prilocaine, mepivacaine) are metabolised principally in the liver; articaine is also substantially hydrolysed in plasma, so it is often preferred in severe liver disease. In significant hepatic impairment, reduce the dose. In the elderly, frail, or medically compromised, use the most conservative maximum and the minimum effective volume.

Sickle cell disease: avoid techniques causing tissue ischaemia. LA with adrenaline is acceptable but use the minimum effective dose; avoid inferior dental blocks where possible.

Paediatric patients: children are dosed strictly by weight, with lower absolute ceilings, and small errors are proportionally more dangerous. A commonly used paediatric figure for lidocaine is 5 mg/kg. Articaine is generally avoided in children under 4 years. Do not extrapolate adult figures. Calculate every paediatric dose from the child's weight and verify against the BNF for Children (BNFc) / DPF — and use the Nosht Paediatric Doses tool.

Signs of local anaesthetic systemic toxicity (LAST) and what to do

Local anaesthetic systemic toxicity (LAST) is a rare but life-threatening emergency, usually from inadvertent intravascular injection or cumulative overdose. Reconcile recognition and management with current Resuscitation Council UK / AAGBI guidance and your practice's medical-emergency protocol.

Early / progressive features (CNS): circumoral/tongue numbness or tingling, metallic taste, light-headedness, tinnitus, visual disturbance, agitation or drowsiness, slurred speech, muscle twitching — progressing to seizures and reduced consciousness.

Later / severe features (cardiovascular): hypotension, bradycardia or tachyarrhythmia, conduction block, and ultimately cardiovascular collapse / cardiac arrest.

1. Stop injecting the local anaesthetic immediately.
2. Call for help / 999, get the emergency kit and AED, and manage ABC — high-flow oxygen, support airway and breathing.
3. Treat seizures (benzodiazepine per protocol) and start CPR if the patient arrests, following Resuscitation Council UK guidance.
4. Lipid emulsion (e.g. Intralipid 20%) is the specific treatment for severe LAST in settings where it is stocked and staff are trained; follow current AAGBI/RCUK guidance. Most general dental practices will not stock lipid emulsion; the priority in primary dental care is resuscitation and urgent transfer.
5. Prevention is the priority: stay within the calculated maximum, aspirate, inject slowly, and use the minimum effective dose.

See also Nosht's medical emergencies in dental practice reference for the wider primary-care emergency picture.

Calculate the patient-specific maximum in Nosht

This page gives you the reference figures and the method. It does not output a dose for an individual patient. For that, use the Nosht Local Anaesthetic Prescriber to calculate the patient-specific maximum: enter the patient's weight and pick the agent, and it returns the patient-specific maximum dose (mg) and the equivalent number of cartridges, with the limiting factor flagged (weight vs absolute cap vs adrenaline ceiling), plus interaction, cardiovascular and pregnancy notes for the agent you select. It covers the five agents in the table above. The calculator is deterministic and works from a fixed UK dental formulary dataset — it does not use a language model to generate doses (by design, for dose safety). Its output is decision-support — the clinician verifies it against the current BNF/SDCEP.

Both clinical tools sit inside the wider Nosht app. Nosht's note-writing features optionally use a clinician-reviewed AI model (Anthropic Claude Haiku 4.5) to help structure clinical notes from your input; the clinical dose tools above are deliberately deterministic calculators and are not generated by AI.

What is the maximum dose of lidocaine in dentistry?

The maximum dose of lidocaine (lignocaine) is weight-based and capped, but for the standard lidocaine 2% with 1:80,000 adrenaline it is usually the adrenaline content that limits you first. The lidocaine ceilings are 7.0 mg/kg, to an absolute maximum of 500 mg, but a healthy-adult adrenaline ceiling of about 200 micrograms equals roughly 320 mg of lidocaine — about 7 cartridges — and that is reached before the lidocaine limit in most fit adults. Each 2.2 ml cartridge of 2% lidocaine contains 44 mg (and 27.5 µg adrenaline). Plain lidocaine has a lower maximum (3.0 mg/kg, up to 200 mg). Calculate the patient-specific maximum from the patient's weight, take the lowest limit, and verify against the current BNF / Dental Practitioners' Formulary (as of June 2026) before administering.

How many cartridges of articaine can I give?

There is no fixed cartridge number — it depends on the patient's weight. Articaine 4% with 1:100,000 adrenaline has a maximum of 7.0 mg/kg, up to 500 mg, and each 2.2 ml cartridge of 4% articaine contains 88 mg. For a fit 70 kg adult, 7.0 × 70 = 490 mg ÷ 88 ≈ ~5.5 cartridges (weight-limited; the adrenaline ceiling does not bite for articaine); for a 50 kg adult it is fewer. Always calculate from the individual patient's weight, reduce for the medically compromised, and verify against the current BNF/DPF. Articaine is generally avoided in children under 4 years.

What is the maximum articaine dose?

For articaine 4% with 1:100,000 adrenaline the maximum is 7.0 mg/kg, to an absolute ceiling of 500 mg in a healthy adult, with 88 mg per 2.2 ml cartridge. The absolute 500 mg cap equates to about 5.6 cartridges at most. Reduce the dose for low body weight, the elderly and the medically compromised, avoid articaine in children under 4 years, and confirm the figure against the current BNF/DPF and the individual patient.

What is the maximum local anaesthetic dose for a child?

Children are dosed strictly by weight, with lower absolute ceilings than adults, so there is no single number — it must be calculated from the child's weight and verified against the BNF for Children (BNFc) / DPF. A commonly used paediatric figure for lidocaine is 5 mg/kg, and articaine is generally avoided in children under 4 years. Never extrapolate adult cartridge counts to children. Use the Nosht Paediatric Doses tool to calculate a weight-based paediatric maximum.

What are the cautions for local anaesthetic in dentistry?

The main cautions are cardiovascular (caution or avoid adrenaline in unstable angina, recent MI and uncontrolled hypertension; a cautious cardiac adrenaline ceiling is about 40 µg per appointment), drug interactions (non-selective beta-blockers and tricyclic antidepressants potentiate adrenaline; recent cocaine use makes adrenaline contraindicated; phaeochromocytoma and uncontrolled thyrotoxicosis warrant avoidance/limitation of adrenaline), methaemoglobinaemia with prilocaine (avoid in G6PD deficiency, significant anaemia and neonates), pregnancy (lidocaine with adrenaline is the usual agent of choice; avoid prilocaine/felypressin), and hepatic impairment, the elderly and the medically compromised (reduce the dose). Always aspirate before adrenaline-containing solutions. Check every patient's medication against the current BNF.

What are the signs of local anaesthetic toxicity?

Early features of local anaesthetic systemic toxicity (LAST) are usually neurological: circumoral/tongue numbness or tingling, metallic taste, light-headedness, tinnitus, visual disturbance, agitation or drowsiness, slurred speech and muscle twitching, which can progress to seizures and reduced consciousness, and then to cardiovascular features (hypotension, arrhythmia, collapse). If suspected: stop injecting, call for help/999, give high-flow oxygen, manage ABC, treat seizures and start CPR if needed per Resuscitation Council UK guidance; lipid emulsion is the specific treatment where available. Prevent it by staying within the calculated maximum, aspirating, injecting slowly, and using the minimum effective dose.