Prilocaine

Generic name: Prilocaine hydrochloride

Category: Amide local anesthetic; available as plain prilocaine or with vasoconstrictor depending on country

Common brand names: Citanest Plain, Citanest Forte, Xylonest, Prilonest. Brand availability, cartridge volume, and vasoconstrictor type vary by country.

This article is for dental education only. Prilocaine should be used only by trained clinicians who understand local anesthetic dosing, aspiration technique, intravascular injection risk, methemoglobinemia risk, patient-specific contraindications, and emergency management of local anesthetic systemic toxicity. Dose must be calculated by milligrams and body weight, not guessed by cartridge number alone.

Prilocaine is an amide local anesthetic used in dentistry for infiltration anesthesia and nerve blocks. A common dental formulation is 4% prilocaine, meaning one 1.8 mL cartridge contains about 72 mg.

Plain prilocaine can be useful for short procedures when a vasoconstrictor-free option is desired. Prilocaine with a vasoconstrictor may be preferred for longer procedures or when improved duration is needed.

The key special warning is methemoglobinemia. Prilocaine can increase methemoglobin levels, especially in susceptible patients or when high doses are used.

• Best use: dental local anesthesia for selected short to moderate procedures
• Common dental context: infiltration anesthesia, inferior alveolar block, restorative dentistry, periodontal care, extractions, minor oral surgery
• Main advantage: effective dental anesthesia with plain or vasoconstrictor-containing options
• Main limitation: special caution for methemoglobinemia and careful dose calculation
• Clinical priority: screen for methemoglobinemia risk, calculate total dose, aspirate, and inject slowly

• Local infiltration anesthesia for short dental procedures
• Inferior alveolar and other dental nerve blocks
• Restorative dentistry when pulpal or soft-tissue anesthesia is required
• Periodontal procedures and scaling when local anesthesia is needed
• Simple extractions and selected minor oral surgery
• Plain anesthetic option when vasoconstrictor exposure should be avoided or minimized
• Vasoconstrictor-containing option when longer duration is needed and the patient is suitable

Example only: A common dental formulation is prilocaine 4%. This means 40 mg/mL. One 1.8 mL cartridge contains about 72 mg prilocaine.

Product information for dental prilocaine commonly lists a maximum of 8 mg/kg in patients under 70 kg, and a maximum of 600 mg in adults weighing 70 kg or more. Some general local-anesthetic references use lower conservative limits, so local product labeling and patient risk should guide the final limit.

For a 70 kg healthy adult, the 600 mg cap equals about 8 cartridges of 4% prilocaine. In real dental care, the practical limit may be lower because of medical risk, methemoglobinemia risk, procedure duration, and whether other local anesthetics were used.

Dose must always consider body weight, age, oxygenation status, liver and kidney function, cardiovascular or pulmonary disease, pregnancy, anemia, G6PD deficiency, oxidizing drugs, total cartridges, aspiration result, and whether vasoconstrictor-containing solutions are used.

• Known hypersensitivity to prilocaine or other amide local anesthetics
• Congenital or idiopathic methemoglobinemia
• Significant G6PD deficiency or history of medication-induced methemoglobinemia without medical input
• Severe anemia, significant hypoxia, or serious cardiopulmonary disease where reduced oxygen delivery would be dangerous
• Use beyond maximum safe dose or without ability to manage toxicity
• Unsafe injection technique or suspected intravascular injection
• Severe liver or kidney disease requiring dose reduction or medical guidance
• Use with other methemoglobinemia-causing drugs in high-risk patients without careful evaluation
• Use of epinephrine-containing prilocaine in patients where vasoconstrictor exposure is medically inappropriate

• Methemoglobinemia: prilocaine can form metabolites that increase methemoglobin and reduce oxygen delivery.
• Delayed presentation: cyanosis, gray/blue skin, shortness of breath, fatigue, dizziness, or abnormal blood color may appear immediately or hours later.
• High-risk patients: infants, G6PD deficiency, congenital methemoglobinemia, anemia, cardiac disease, lung disease, hypoxia, and oxidizing drugs increase risk.
• Local anesthetic systemic toxicity: may occur after overdose, rapid absorption, repeated dosing, or intravascular injection.
• Early toxicity signs: metallic taste, circumoral numbness, tinnitus, dizziness, agitation, confusion, visual disturbance, tremor, or slurred speech.
• Severe toxicity: seizures, respiratory depression, arrhythmia, cardiovascular collapse, or cardiac arrest.
• 4% concentration: one cartridge contains about 72 mg, so repeated cartridges can reach a high total dose quickly.

Prilocaine is not just “another plain local anesthetic.” Its special exam and clinic warning is methemoglobinemia. Ask about G6PD deficiency, previous blue/gray skin after medicines, anemia, lung disease, heart disease, and oxidizing medications before using high doses.

• Other local anesthetics: total local anesthetic dose is additive and increases toxicity risk.
• Methemoglobinemia-associated drugs: dapsone, nitrates, nitrites, sulfonamides, phenazopyridine, nitrofurantoin, antimalarials, and some oxidizing agents may increase risk.
• Benzocaine topical anesthetics: may also increase methemoglobinemia risk, especially with high exposure or susceptible patients.
• Class I antiarrhythmic drugs: may have additive cardiac effects with local anesthetics.
• CNS depressants or sedatives: may complicate recognition of neurologic toxicity symptoms.
• Hepatic or renal impairment: may affect prilocaine handling and increase concern with repeated or high doses.
• If epinephrine is included: interactions similar to other epinephrine-containing dental anesthetics must be considered, including nonselective beta-blockers, TCAs, MAO inhibitors, stimulants, and some antipsychotics.

• Temporary numbness of lip, cheek, tongue, or soft tissues
• Injection-site pain, bruising, or hematoma
• Dizziness, lightheadedness, headache, nausea, or mild drowsiness
• Prolonged numbness or altered sensation requiring follow-up
• Rare allergy to amide local anesthetics
• Methemoglobinemia with cyanosis, gray/blue skin color, shortness of breath, fatigue, abnormal oxygen saturation, or chocolate-brown blood
• If epinephrine is included: palpitations, tremor, anxiety-like feeling, increased heart rate, or blood pressure changes
• Rare but serious: seizure, arrhythmia, respiratory depression, cardiovascular collapse, severe systemic toxicity
• Post-anesthetic lip, cheek, or tongue biting injury

• Do not chew food until the numbness has worn off to avoid biting the lip, cheek, or tongue.
• Children should be supervised while numb because they may bite or suck numb tissues.
• Tell the dentist about anemia, lung disease, heart disease, G6PD deficiency, previous blue/gray skin after medicine, pregnancy, and all medications.
• Report previous reactions to dental anesthesia, including fainting, rash, swelling, breathing difficulty, palpitations, or persistent numbness.
• Seek urgent help for blue/gray skin color, breathing difficulty, chest pain, severe dizziness, seizure, confusion, facial swelling, throat swelling, or collapse.
• Contact the clinic if numbness lasts unusually long, altered sensation persists, swelling worsens, severe pain develops, or infection signs appear.

The memory point for prilocaine is: “effective dental anesthetic, but think methemoglobinemia.” If a patient develops cyanosis or low oxygen saturation that does not improve as expected with oxygen after local anesthetic exposure, prilocaine-related methemoglobinemia should be considered urgently.

• Blue/gray skin color, shortness of breath, fatigue, dizziness, abnormal oxygen saturation, or chocolate-brown blood
• Cyanosis that does not improve as expected with oxygen
• Metallic taste, circumoral numbness, tinnitus, visual disturbance, agitation, confusion, tremor, slurred speech, or seizure after injection
• Severe dizziness, fainting, collapse, or altered consciousness
• Irregular heartbeat, chest pain, severe hypotension, or cardiovascular collapse
• Difficulty breathing, wheezing, facial swelling, throat swelling, or suspected allergic reaction
• Persistent numbness, tingling, altered sensation, or neurologic symptoms after anesthesia
• Any suspected local anesthetic systemic toxicity or methemoglobinemia requiring emergency management

• Lidocaine + Epinephrine
• Articaine + Epinephrine
• Mepivacaine
• Bupivacaine + Epinephrine
• Epinephrine / Adrenaline
• Felypressin
• Topical benzocaine
• Methylene blue for methemoglobinemia management
• Lipid emulsion therapy for severe local anesthetic systemic toxicity

Prilocaine is an amide local anesthetic used in dentistry as a 4% solution, either plain or with a vasoconstrictor depending on the product and country. It is useful for infiltration anesthesia, nerve blocks, short procedures, and selected cases where vasoconstrictor exposure should be minimized. Safe use requires milligram-based dose calculation, aspiration, slow injection, attention to additive local anesthetic dose, and special screening for methemoglobinemia risk. The key dental habit is to remember that one 1.8 mL cartridge of 4% prilocaine contains about 72 mg, and the key clinical warning is cyanosis or low oxygen saturation after exposure.