EMLA Cream Onset of Action
EMLA cream requires 60 minutes of application under occlusion to reach full effectiveness on intact skin. 1, 2
Standard Application Time
- The American Academy of Pediatrics clearly states that EMLA reaches full effectiveness in 60 minutes, which is the standard recommendation for clinical practice 1, 2
- This 60-minute application time is required when EMLA is applied under an occlusive dressing on intact skin 1, 2
- For optimal results, the cream should be applied with an occlusive dressing such as Tegaderm to enhance absorption 3
Depth of Anesthesia by Application Time
The depth of cutaneous anesthesia achieved varies significantly with application duration:
- After 30 minutes: Minimal anesthesia, generally insufficient for most procedures 4, 5
- After 60 minutes: Adequate anesthesia to approximately 3 mm depth 6
- After 120 minutes: Anesthesia extends to approximately 4-5 mm depth 6
- After 3-4 hours: Maximum anesthesia up to 6 mm depth 6
Faster Alternatives to Consider
When 60 minutes is too long to wait, several alternatives provide more rapid onset:
- Liposomal 4% lidocaine cream (LMX4) reaches full effectiveness in approximately 30 minutes 1, 2
- Heat-activated lidocaine systems work in as little as 10-20 minutes 1, 2
- Lidocaine-epinephrine-tetracaine (LET) combinations for open wounds provide anesthesia in 10-20 minutes 2
- Iontophoresis of lidocaine delivers greater anesthesia than EMLA at 30 minutes 5
- Ultrasound pretreatment can reduce EMLA onset time to as little as 5-15 minutes, though this requires specialized equipment 7
Critical Contraindications
Before applying EMLA, verify the patient does NOT have:
- Allergy to amide anesthetics 1, 2
- Non-intact skin (EMLA is contraindicated on open wounds due to systemic absorption risks) 1, 8
- Recent sulfonamide antibiotic use (trimethoprim-sulfamethoxazole, erythromycin-sulfisoxazole) 1, 2
- Congenital or idiopathic methemoglobinemia 1, 2
- Age <12 months or weight <10 kg (requires dose reduction) 1, 2
Common Pitfalls to Avoid
- Expecting complete pain relief: Topical anesthetics like EMLA do not provide complete pain elimination for all procedures 1, 2
- Inadequate application time: Applying EMLA for less than 60 minutes results in suboptimal anesthesia 4, 6
- Forgetting occlusion: EMLA requires an occlusive dressing to work effectively 3, 9
- Using on inappropriate sites: Avoid fingers, nose, ears, eyelids, and near lips where vascular compromise could occur 1
- Failing to apply to multiple sites: For IV placement, apply to at least 2 potential venipuncture sites since some patients may require a procedure before full effectiveness is reached 1, 2