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L.M.X.4 (Lidocaine 4%)

What is L.M.X.4 (Lidocaine 4%)?

L.M.X.4 is a topical anesthetic cream that is similar to EMLA.

At the nerve endings, L.M.X.4 causes numbing of the skin and surrounding tissue.

Applying 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.
  • While wearing gloves, begin by rubbing a small amount of L.M.X.4 cream into each of the sites for about 30 seconds.
  • Apply another layer of L.M.X.4 cream, this time with a thicker coating of the cream. Cover cream with an occlusive dressing (Tegaderm or round bandages).  
  • 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.

L.M.X.4 starts to work in about 30 minutes.

Total application time should usually not exceed 60 minutes. (Rubbing it in longer has not been shown to increase its effect).

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 two hours.
  • Make sure to wear gloves during application and wash hands after applying.

Possible Side Effects of Medication

  • Redness, irritation at the site of the cream
  • Swelling, abnormal sensation at the site of the cream
  • Rash

L.M.X.4 Compared to EMLA

  L.M.X.4 EMLA
Over-the-counter Prescription only
Lidocaine 4% Lidocaine 2.5% / Prilocaine 2.5%
Application Time
30 min – Venipuncture/LP 60 min – Venipuncture / LP

120 min – Skin graft harvesting
5-15 min – genital mucosa

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
of Effect
60 min after removal 60-120 min after removal
ADRs Redness, irritation, itching, rash Local blanching, redness, erythema, methemoglobinemia
Approved Ages
>2 years old >37 weeks EGA
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)
Approved uses
studied in children
IV catheter placement, Venipuncture, circumcision, LP Circumcision, anal fissures, IM immunizations, LP, cryotherapy for warts
Warnings /
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

Last Updated 11/2019