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). For children, use the weight-based limits in our paediatric dental doses guide.

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), using the figures in the table above:

• 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: 4.5 × 70 = 315 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: the dental SmPC gives no adult mg/kg, only a 10 ml (300 mg) maximum → 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 — about 1.5 cartridges of 1:80,000 (27.5 µg each), ~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 — use a maximum of two adrenaline-containing cartridges (NHS SPS) and aspirate carefully.
• Tricyclic antidepressants (e.g. amitriptyline): potentiated pressor response to adrenaline — use the minimum effective dose and a maximum of two adrenaline-containing cartridges (NHS SPS).
• MAOIs: the BNF interactions entry says adrenaline might increase the risk of a hypertensive crisis and the manufacturer advises avoiding it (and for 14 days after stopping the MAOI); the NHS Specialist Pharmacy Service advises that a clinically significant interaction is unlikely with dental cartridges used as licensed, but Scandonest Special and Orabloc are contraindicated with MAOIs. SDCEP gives no specific advice. Felypressin or a plain agent 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 widely used in dentistry; in pregnancy it crosses the placenta but is not known to be harmful in animal studies, so use it if the benefit outweighs the risk (BNF). Articaine has no information in pregnancy, so use it only after a careful benefit-risk assessment, preferring the 1:200,000 product for its lower adrenaline (BNF; Septanest SmPC 4.6). Prilocaine with felypressin should not be given in early pregnancy unless the benefits outweigh the risks (Citanest with Octapressin Dental SmPC 4.6), and mepivacaine is used with caution in early pregnancy (BNF). 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 guidance, the Association of Anaesthetists (formerly AAGBI) safety guideline Management of Severe Local Anaesthetic Toxicity, 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 the current Association of Anaesthetists (formerly AAGBI) LA toxicity guideline and 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.

Check LA maximum-dose figures 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 Dose Reference: enter the patient's weight and pick the agent, and it shows the published 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 a reference aid — 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.

Sources

• BNF: Lidocaine hydrochloride (accessed 11 October 2026)
• BNF: Lidocaine with adrenaline (accessed 11 October 2026)
• BNF: Prilocaine with felypressin (accessed 11 October 2026)
• BNF: Mepivacaine hydrochloride (accessed 11 October 2026)
• BNF: Prescribing in dental practice (accessed 11 October 2026)
• SDCEP: Drug Prescribing for Dentistry (accessed 11 October 2026)