[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Dentistry](https://durgical.com/en/dentistry/) › [Drugs in dentistry](https://durgical.com/en/dentistry/areas/drugs/) › Local anaesthetics in dentistry # Local anaesthetics in dentistry - Drugs Local anaesthetics block sodium channels in nerves so the patient feels no pain. In dentistry most are amides, often combined with adrenaline. Updated Nov 12, 2026 ## Key points - Local anaesthetics block sodium channels; small pain fibres first. - Dental injections: amides; topical gels: often esters. - True amide allergy is rare; prilocaine and benzocaine cause methaemoglobinaemia. ## What it is Local anaesthetics block voltage-gated sodium channels from inside the nerve membrane, stopping the action potential; small pain fibres are blocked first. Two chemical groups exist. Amides (lidocaine, articaine, mepivacaine, prilocaine, bupivacaine) are used for dental injections; they are metabolised in the liver, except articaine, which is mostly broken down in plasma because of an ester group. Esters (benzocaine, tetracaine) are used mainly as topical gels and sprays and are broken down by plasma esterases into para-aminobenzoic acid, which explains most true allergies. Dental cartridges usually contain a vasoconstrictor (adrenaline, or felypressin with prilocaine) to prolong the effect and reduce bleeding and systemic absorption. ## What to know - Lidocaine with adrenaline is the reference dental anaesthetic. - Articaine diffuses well through bone and has a short half-life. - Mepivacaine without vasoconstrictor is an option when adrenaline should be limited. - Bupivacaine gives long anaesthesia for surgery but is the most cardiotoxic. - Inflamed, acidic tissue reduces effectiveness because less drug is in the non-ionised, membrane-crossing form. ## Risks and precautions - True allergy to amide anaesthetics is very rare; most reactions are fainting, anxiety, intravascular adrenaline or sensitivity to sulphite preservatives in adrenaline-containing solutions. - Prilocaine and benzocaine can cause methaemoglobinaemia, especially in infants and with large amounts. - The maximum safe amount depends on body weight: small children are most at risk of overdose, particularly when several cartridges are used. - Self-injury: children may bite numb lips and tongue after treatment. ## Next step / Initial management - Before injecting: ask about previous reactions, heart disease, liver disease, interacting drugs and weight in children; aspirate before injecting. - Suspected allergy to a local anaesthetic: refer to an allergy service for testing rather than avoiding all local anaesthetics. - Warn patients and parents about numbness and lip biting; refer any persistent numbness after an injection back to the dentist. ## Test yourself Think of the answer, then tap the question to see it. ## What is the mechanism of action of local anaesthetics? They block voltage-gated sodium channels from inside the nerve membrane, preventing action potentials. ## Why are local anaesthetics less effective in infected tissue? The acidic environment increases the ionised fraction, which cannot cross the nerve membrane. ## Which two local anaesthetics are classically linked to methaemoglobinaemia? Prilocaine and benzocaine. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/dentistry/local-anaesthetics-in-dentistry/) ## Connections ## Related 4 - [Adrenaline in dental anaesthesia: when to be careful](https://durgical.com/en/dentistry/adrenaline-in-dental-anaesthesia-when-to-be-careful/) - [Local anaesthetic toxicity and methaemoglobinaemia](https://durgical.com/en/dentistry/local-anaesthetic-toxicity-and-methaemoglobinaemia/) - [Dental nerve blocks and infiltration: the anatomy behind them](https://durgical.com/en/dentistry/dental-nerve-blocks-and-infiltration-the-anatomy-behind-them/) - [Nerves of the teeth and mouth: trigeminal (V) and facial (VII)](https://durgical.com/en/dentistry/nerves-of-the-teeth-and-mouth-trigeminal-and-facial/) ## In Pharmacology 8 - [Local anesthetics](https://durgical.com/en/pharmacology/classes/local-anesthetics/) - [Lidocaine](https://durgical.com/en/pharmacology/lidocaine/) - [Articaine](https://durgical.com/en/pharmacology/articaine/) - [Mepivacaine](https://durgical.com/en/pharmacology/mepivacaine/) - [Prilocaine](https://durgical.com/en/pharmacology/prilocaine/) - [Bupivacaine](https://durgical.com/en/pharmacology/bupivacaine/) - [Benzocaine](https://durgical.com/en/pharmacology/benzocaine/) - [Epinephrine](https://durgical.com/en/pharmacology/epinephrine/) [← All of dentistry](https://durgical.com/en/dentistry/) Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once. Sources: [Local Anesthetic Drugs Used In Dentistry](https://www.ncbi.nlm.nih.gov/books/NBK610935/) (StatPearls Publishing (NCBI Bookshelf), 2025); [Topical, Local, and Regional Anesthesia and Anesthetics](https://www.ncbi.nlm.nih.gov/books/NBK430894/) (StatPearls Publishing (NCBI Bookshelf), 2025); [Local Anesthetics in Children](https://www.ncbi.nlm.nih.gov/books/NBK572090/) (StatPearls Publishing (NCBI Bookshelf), 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/dentistry/local-anaesthetics-in-dentistry/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/dentistry/local-anaesthetics-in-dentistry/