Local Anesthesia Cheat Sheet: Doses, Max Volumes, and When to Use Each

Local anesthesia is one of the few skills in dentistry where the margin for error is narrow and the consequences of a mistake are immediate. Overdose, intravascular injection, and the wrong agent for a medically complex patient are all avoidable — if you know the rules.

This post summarizes the core principles. It's not a replacement for Malamed's Handbook of Local Anesthesia, your faculty, or drug package inserts. Always verify doses against current references before clinical use.

The Rules You Need to Know Cold

1. Maximum recommended doses are weight-based.

For every local anesthetic, the maximum recommended dose is expressed in mg/kg. You must calculate the patient's total allowable dose before the first cartridge.

The maximum recommended doses (per Malamed's Handbook of Local Anesthesia, the standard U.S. reference) for common dental anesthetics in healthy adults are:

• Lidocaine (2%) with epinephrine 1:100,000 or 1:50,000: 7.0 mg/kg, not to exceed 500 mg
• Articaine (4%) with epinephrine 1:100,000 or 1:200,000: 7.0 mg/kg, not to exceed 500 mg (in adults)
• Mepivacaine (2%) with levonordefrin or (3%) plain: 6.6 mg/kg, not to exceed 400 mg
• Bupivacaine (0.5%) with epinephrine 1:200,000: 2.0 mg/kg, not to exceed 90 mg
• Prilocaine (4%) plain or with epinephrine: 8.0 mg/kg, not to exceed 600 mg

Always verify these against the most current package insert — manufacturer-recommended maximums can be updated.

2. Know how much drug is in each cartridge.

A standard dental cartridge contains 1.8 mL (some are 1.7 mL — check your product).

The amount of anesthetic per cartridge:

• 2% lidocaine × 1.8 mL = 36 mg per cartridge
• 4% articaine × 1.8 mL = 72 mg per cartridge
• 3% mepivacaine × 1.8 mL = 54 mg per cartridge
• 0.5% bupivacaine × 1.8 mL = 9 mg per cartridge

To compute allowable cartridges: (patient's max mg dose) ÷ (mg per cartridge).

3. Know how much epinephrine is in each cartridge.

Vasoconstrictor dose matters independently of anesthetic dose, especially for medically compromised patients.

• 1:100,000 epinephrine = 0.01 mg/mL = 0.018 mg per 1.8 mL cartridge
• 1:200,000 epinephrine = 0.005 mg/mL = 0.009 mg per 1.8 mL cartridge

For a healthy adult, the generally accepted maximum dose of epinephrine is 0.2 mg per appointment (approximately 11 cartridges at 1:100,000).

For patients with significant cardiovascular disease, the recommendation is typically limited to 0.04 mg per appointment (approximately 2 cartridges at 1:100,000). This is the widely cited "cardiac dose" based on American Heart Association / American Dental Association joint recommendations.

4. The medical history changes the anesthetic.

Hypertension (well-controlled): 1:100,000 epinephrine is generally safe; limit to 2 cartridges if BP is elevated at appointment.

Uncontrolled hypertension: Postpone elective care. For emergency care, minimize or avoid vasoconstrictor.

Ischemic heart disease / recent MI: Use minimal effective epinephrine; the cardiac dose applies. Use plain anesthetic when possible.

Pregnancy: Lidocaine with epinephrine (Category B) is generally considered acceptable for necessary dental care. Avoid elective care in the first trimester when possible.

Hyperthyroidism (uncontrolled): Avoid epinephrine-containing solutions.

Liver disease: Amide anesthetics (lidocaine, articaine, mepivacaine, bupivacaine, prilocaine) are metabolized hepatically; dose conservatively.

Methemoglobinemia risk (G6PD deficiency, infants): Avoid prilocaine and benzocaine.

Sulfite allergy: Vasoconstrictor-containing solutions contain sodium metabisulfite as a preservative; use plain anesthetic.

5. The technique changes the success rate.

• Infiltration: Effective for maxillary teeth; effective for mandibular anterior teeth. Generally not effective alone for mandibular posterior teeth in adults (cortical bone is too dense).
• Inferior alveolar nerve block (IANB): Primary technique for mandibular molars and premolars; failure rate reported in the literature is meaningful, often due to anatomical variation.
• Gow-Gates / Vazirani-Akinosi: Alternative mandibular blocks when IANB fails or when the patient cannot open wide.
• Articaine infiltration: Clinical evidence suggests articaine buccal infiltration has higher success than lidocaine infiltration for mandibular molars in some scenarios, though it is not a substitute for IANB in all cases.
• PSA block: Anesthetizes maxillary molars (often except the mesiobuccal root of the first molar, which may require a supplemental injection).
• Nasopalatine block / greater palatine block: Palatal anesthesia for maxillary anterior / posterior regions.

Recognizing and Managing Overdose

Local anesthetic systemic toxicity (LAST) is rare but real. Classic progression:

1. 1Early CNS excitation: restlessness, tremor, dizziness, tinnitus, metallic taste
2. 2CNS depression: drowsiness, unconsciousness
3. 3Seizure
4. 4Respiratory arrest
5. 5Cardiovascular collapse

If you suspect LAST: stop injection, call EMS, support ABCs, consider lipid emulsion therapy per ASRA guidelines at a hospital setting.

Clinical Pearls

• Always aspirate before injecting. Intravascular injection is the leading cause of high plasma levels.
• Inject slowly. 1 mL per minute is the generally accepted rate. Fast injection increases the risk of both toxicity and patient discomfort.
• Document every cartridge. Record the drug, concentration, vasoconstrictor, and number of cartridges in the patient's chart.
• Know your patient's weight before you inject. For pediatric patients especially, weight-based dosing is non-negotiable.

Bottom Line

Local anesthesia is a calculated skill. Know the mg/kg maximums, know what's in each cartridge, and let the medical history guide your agent choice. The students who master these five rules never have a serious problem with LA.

Sources & References

• Malamed SF. Handbook of Local Anesthesia, current edition — primary clinical reference
• American Dental Association / American Heart Association — vasoconstrictor recommendations in cardiac patients
• ASRA (American Society of Regional Anesthesia) — LAST management guidelines
• FDA package inserts — manufacturer dosing limits

This post is educational content only. Always verify doses against current package inserts and follow your clinical preceptors' protocols.