What are the guidelines for using Emla (lidocaine and prilocaine) cream for topical anesthesia in patients with various medical conditions and demographics?

EMLA Cream Guidelines for Topical Anesthesia

EMLA cream (2.5% lidocaine/2.5% prilocaine) is the preferred topical anesthetic for minor procedures on intact skin, requiring 60 minutes under occlusive dressing for full effectiveness, with specific contraindications in infants under 12 months receiving methemoglobin-inducing agents and patients with recent sulfonamide antibiotic use. 1

Approved Clinical Applications

EMLA should be used for the following non-emergent procedures on intact skin:

• IV line placement and venipuncture - Apply to at least 2 sites over accessible veins 2
• Lumbar puncture - Apply as soon as the decision is made to perform the procedure 2
• Minor dermatologic procedures including skin biopsy, small excisions, filler and botulinum toxin injections 1
• Nonablative laser treatments (Strength A recommendation for children's laceration repair, Strength C for other uses) 1
• Reducing pain of subsequent infiltrative anesthetic injection 1
• Subcutaneous injections including erythropoietin administration 3

Off-Label Use for Laceration Repair

EMLA provides topical anesthesia for laceration repair, though this is not FDA-approved 2. For open wounds, LET solution (lidocaine, epinephrine, tetracaine) is preferred as it achieves anesthesia in 10-20 minutes 2, 4.

Application Protocol

Timing Requirements

• EMLA requires 60 minutes under occlusive dressing to reach full effectiveness 2, 1, 4, 3
• Apply at triage for patients with high likelihood of requiring needle procedures 4
• Insufficient application time is a common error that reduces efficacy 4

Application Technique

• Apply adequate amount under occlusive dressing 5
• Avoid mucous membrane contact or ingestion 2
• After applying, wash hands with soap and water 6

Absolute Contraindications

Do not use EMLA in the following situations:

• Emergent need for immediate IV access 2, 4
• Allergy to amide anesthetics 2, 4, 3
• Non-intact skin (except for wound repair formulations) 2, 4
• Recent sulfonamide antibiotic use (trimethoprim-sulfamethoxazole, erythromycin-sulfisoxazole) 2, 3
• Congenital or idiopathic methemoglobinemia 2, 3
• Infants <12 months receiving methemoglobin-inducing agents 3

Special Population Dosing

Pediatric Patients

• Patients <12 months or <10 kg require dose reduction 2, 1, 4, 3
• Infants under 6 months should have doses reduced by 30% 1, 4
• Use 0.5 g to 2 g maximum in neonates 7

Pregnant and Nursing Women

• Topical lidocaine is safe for pregnant or nursing women 1, 4
• Insufficient evidence exists for EMLA safety in pregnancy/lactation - choose alternative lidocaine formulations instead 1, 4

Adults

• Maximum safe dose is 4.5 mg/kg without epinephrine or 7.0 mg/kg with epinephrine 1, 4
• Apply not more than 3 to 4 times daily 6

Safety Considerations and Adverse Effects

Methemoglobinemia Risk

• Methemoglobinemia is a possible risk with EMLA 1
• Risk factors include excessive amount, large application area, prolonged application time, diseased/inflamed skin, age <3 months, prematurity, and concomitant methemoglobin-inducing agents 8
• Clinical trials following manufacturer guidelines reported clinically insignificant methemoglobin levels 8

Local Reactions

• Transient erythema is common, especially with mucosal applications 9
• Transient burning sensation may occur but generally disappears in several days 6
• Mild local skin reactions include edema, pallor, and erythema 8

Serious Complications (Rare)

• Central nervous system toxicity and cardiotoxicity can occur with excessive use 8
• Rare cases of serious burns have been reported 6

Clinical Algorithm for Topical Anesthetic Selection

Choose EMLA when:

• Time permits 60-minute application 1, 4
• Patient is not pregnant or nursing 1, 4
• Patient has no contraindications listed above 2
• Procedure is on intact skin 2, 1

Choose alternative lidocaine formulations (LMX4) when:

• Faster onset required (30 minutes) 2, 1, 4
• Patient is pregnant or nursing 1, 4
• Methemoglobinemia risk is a concern 1

Choose LET solution when:

• Procedure involves open wounds/lacerations 2, 4
• Faster onset needed (10-20 minutes until wound edges blanch) 2, 4

Choose intradermal lidocaine when:

• Procedure cannot be delayed 2
• Buffering with bicarbonate and warming minimizes injection pain 2, 4

Important Clinical Pearls

• EMLA does not provide complete pain relief - counsel parents/patients accordingly 2
• Topical anesthetics improve procedural success rates by decreasing patient movement 2
• Do not bandage or apply local heat (such as heating pads) to the area 6
• Prolonged application (30-45 minutes) can cause excessive numbness that may interfere with the procedure 4
• EMLA showed lowest efficacy for circumcision (~80% required additional anesthesia) 9
• EMLA is highly effective for mucosal lesions (99.5% efficacy in penile mucosal procedures) 9
• EMLA did not reduce pain from heel lancing in neonates in multiple randomized trials 7