L.M.X.4 (Lidocaine 4%)
What is L.M.X.4?
L.M.X.4 is a topical anesthetic cream that is similar to EMLA.
How does L.M.X.4 work?
At the nerve endings, L.M.X.4 causes numbing of the skin and surrounding tissue.
How do I apply L.M.X.4?
- DO NOT CLEANSE THE SKIN prior to L.M.X.4 application (although you should not apply over moisturizers or other topical medications).
- L.M.X.4 works best when it mixes with the skin surface oils.
- Begin by rubbing a small amount of L.M.X.4 cream into each of the sites for ~ 30 seconds. Make sure you are wearing gloves.
- Follow this application with a thicker coating of L.M.X.4 cream. Cover cream with an occlusive dressing (ex. Tegaderm or round Band-aids).
- Although L.M.X.4 does not require the use of an occlusive dressing, one is recommended for use in children to ensure adequate contact of the cream with the skin and to prevent the accidental ingestion of the cream.
- Do NOT flatten the cream (L.M.X.4 works best when it is applied thickly).
- After the product is removed, the skin should be cleaned and prepared as usual for the procedure.
How long does it take for L.M.X.4 to work?
L.M.X.4 starts to work in ~ 30 minutes.
Total application time should usually not exceed 60 minutes (rubbing it in longer has not been shown to increase its effect).
How long does the effect of L.M.X.4 last?
It lasts approximately 60 minutes.
Special Instructions:
- Keep this medication out of the reach of children.
- If too much medicine is taken by accident, call the Drug and Poison Information Center (DPIC), 513-636-5111 or 1-800-222-1222, or call your child's doctor immediately.
- Do not repeat application/dose to the same part of the body within 2 hours.
- Wash hands after applying.
If a dose is missed
For any medication information related to your child's dosing schedule and/or missed doses, contact the healthcare provider who prescribed the medication.
Side Effects
Contact your child's doctor if symptoms persist or become bothersome:
- Redness, irritation at the site of the cream
- Swelling, abnormal sensation at the site of the cream
- Rash
How does L.M.X.4 differ from EMLA?
| |
L.M.X.4 |
EMLA |
| Prescription Status |
Over-the-Counter |
Prescription Only |
| Active Ingredients |
Lidocaine 4% |
Lidocaine 2.5% / Prilocaine 2.5% |
| Recommended Application Time |
30 min – Venipuncture/LP |
60 min – Venipuncture/LP 120 Min – Skin graft harvesting
5-15 min – genital mucosa |
| Maximum Application Time |
60 min (no added benefit with longer application) May be left on up to 120 min |
60 min (<3mo or <5kg) 240 min (4 hrs) for all others |
| Duration of Effect |
60 min after removal |
60-120 min after removal |
| ADR's |
Redness, irritation, itching, rash |
Local blanching, redness, erythema, Methemoglobinemia |
| FDA Approved Ages |
>2 years old |
>37 weeks EGA |
| FDA Approved Uses |
Minor cuts, minor burns, minor scrapes, minor skin irritations, sunburn, and insect bites |
IV catheter placement, Venipuncture, split skin graft harvesting, genital mucosa (adjunct to local infiltration) |
| Non-FDA Approved uses studied in children |
IV catheter placement, Venipuncture, circumcision, LP |
Circumcision, anal fissures, IM Immunizations, LP, cryotherapy for warts |
| Warnings/Precautions |
Do no use on raw areas or blisters |
Use with caution in patients at risk for developing Methemoglobinemia or with severe hepatic disease |
| Size |
5, 15, 30gm tubes. 5gm tube has 3 Tegaderm patches. |
30gm tube |
Table 1 – Recommended application amount and time based on patients age (taken from EMLA package insert)
| Age and Body Weight |
Maximum Total Dose of EMLA |
Maximum Application Area |
Maximum Application Time |
| 0 up to 3 mos or < 5 kg |
1 g |
10 cm² |
1 hour |
| 3 up to 12 months and > 5 kg |
2 g |
20 cm ² |
4 hours |
| 1 to 6 years and > 10 kg |
10 g |
100 cm ² |
4 hours |
| 7 to 12 years and > 20 kg |
20 g |
200 cm ² |
4 hours |
Rev. 6/07, 9/07
