Prilocaine

Local anesthetics
Local anesthetics

Intermediate-acting amide local anaesthetic, mostly dental and in a skin cream with lidocaine. Its o-toluidine metabolite causes methaemoglobinaemia.

Updated Nov 1, 2026

Also called: Prilocaine hydrochloride

Quick facts

Group: Local anesthetics
Target: Voltage-gated sodium channels (Nav)
Used for: Dental infiltration · Intravenous regional anaesthesia
Key effects: Skin cream · Abnormal sensation at the treated area
Monitor: Skin and lip colour and pulse oximetry
ATC: N01BB04

No doses: the clinician sets them by the current guideline.

Mechanism of action

Voltage-gated sodium channels (Nav)Prilocaine

There is no structure with prilocaine. The figure shows levobupivacaine, another amide local anaesthetic, in the inner pore of the human Nav1.7 sodium channel.

Target in 3D: Voltage-gated sodium channels (Nav). PDB structure 8I5B (RCSB PDB, public domain). View the structure at RCSB PDB

Prilocaine is an amide local anaesthetic: its un-ionised form crosses the nerve membrane and, from inside, blocks the voltage-gated sodium channel so that no action potential travels and pain is not felt. It causes little vasodilation, so it can be used without a vasoconstrictor, and its large volume of distribution lowers its CNS toxicity. Unlike other amides, it is first hydrolysed to o-toluidine, which oxidises haemoglobin to methaemoglobin.

Crosses the nerve membrane in its un-ionised form
Blocks the sodium channel from inside
No action potential: local loss of pain
Metabolism to o-toluidine can produce methaemoglobin

Indications

Dental infiltration and nerve-block anaesthesia
Topical anaesthesia of intact skin with lidocaine (eutectic cream) before venepuncture, cannulation or superficial procedures, and of genital mucosa for minor surgery
Intravenous regional anaesthesia, where it is suitable because of its low CNS toxicity

Adverse effects

Common

Skin cream: transient paleness, then redness or swelling at the site
Abnormal sensation at the treated area
Signs of systemic toxicity with high levels: perioral numbness, dizziness, tinnitus

Contraindications

Hypersensitivity to amide-type local anaesthetics or to any component

Key interactions

Other methaemoglobin-forming drugs (nitrates and nitrites such as nitric oxide and nitroglycerin, dapsone, sulfonamides, nitrofurantoin, acetaminophen, metoclopramide, quinine): Higher risk of methaemoglobinaemia.
Other local anaesthetics: Additive systemic toxicity; total amounts from all products are added up.

What is monitored

Skin and lip colour and pulse oximetry; methaemoglobin level if cyanosis appears
Consciousness and early signs of toxicity after injection
In infants and children: treated area and application time

Administration and safety

The cream goes on intact skin under an occlusive dressing, ahead of the procedure; not on open wounds or near the eyes.
It is not used where it could pass the eardrum into the middle ear.
Dental injection: aspirate before injecting and inject slowly.
Amounts from different local anaesthetic products are added together.

Pregnancy and breastfeeding

Animal studies with lidocaine and prilocaine showed no fetal harm; it is not contraindicated in labour. Lidocaine, and probably prilocaine, pass into breast milk.

Nursing care

Ask about G6PD deficiency, methaemoglobinaemia and methaemoglobin-forming drugs before use.
Check the skin after removing the cream and watch infants closely.
Teach the signs of methaemoglobinaemia and to seek care at once if they appear.
Protect the numb area (eye, mouth, skin) from injury until sensation returns.

Pharmacokinetics

Absorption: Systemic absorption depends on site, area and time of contact; from the skin cream it grows with area and application time.
Distribution: Large volume of distribution.
Metabolism: Hydrolysed (liver and kidney) to o-toluidine metabolites.
Half-life: Prolonged in liver or kidney dysfunction.

Test yourself

Think of the answer, then tap the question to see it.

Which metabolite of prilocaine causes methaemoglobinaemia?

o-Toluidine, formed by hydrolysis of prilocaine.

Which patients are at highest risk of methaemoglobinaemia from prilocaine?

Patients with G6PD deficiency or congenital methaemoglobinaemia, those with heart or lung compromise, and infants under six months.

How is prilocaine-induced methaemoglobinaemia treated if needed?

Intravenous methylene blue, together with oxygen and supportive care.

Why is a eutectic lidocaine–prilocaine cream able to anaesthetise intact skin?

The mixture melts below room temperature into an oil that penetrates intact skin under an occlusive dressing.

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Connections

← Back to the class: Local anesthetics

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - LIDOCAINE AND PRILOCAINE cream (DailyMed (U.S. National Library of Medicine), 2026); Lidocaine and Prilocaine Topical: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.