Emla Numbing Cream is a topical anesthetic designed to temporarily dull sensation on the skin’s surface before minor procedures. This product is a eutectic mixture of local anesthetics, containing lidocaine (2.5%) and prilocaine (2.5%) for a 5% total anesthetic concentration. The primary purpose of EMLA Cream is to provide localized pain relief, making procedures involving needles or superficial skin manipulation more comfortable.
Mechanism of Action
The localized numbing effect results from the interaction of lidocaine and prilocaine with nerve cells in the skin. Both are amide-type local anesthetic agents that stabilize the neuronal membrane by blocking voltage-gated sodium channels. This action prevents the initiation and conduction of nerve impulses, effectively stopping pain signals from traveling to the brain.
The cream is formulated as a eutectic mixture, meaning the combination of lidocaine and prilocaine has a lower melting point than either anesthetic alone, which enhances skin penetration. While pain is temporarily blocked, patients may still experience the sensation of pressure or touch. The depth and duration of analgesia depend on the amount of cream applied and the time it is left on the skin.
Essential Application Guidelines
Proper application is necessary for effectiveness and safety. Begin by cleaning the application site to ensure the skin is intact and free of dirt or oils. Apply a thick layer of the cream to the designated area; the cream should not be rubbed into the skin.
To maximize absorption, the cream must be covered with an occlusive dressing, such as a specialized patch or plastic wrap. This dressing prevents the cream from drying out and forces the anesthetic agents into the deeper layers of the skin. For most minor procedures like venipuncture, the cream should remain on the skin for at least 60 minutes to achieve sufficient numbing.
For more involved procedures, such as a skin graft harvest, an application time of two hours or more may be required. The maximum recommended duration is typically four hours, and the cream must be completely wiped off before the procedure begins. The numbing effect usually persists for about one to two hours after removal.
Primary Medical and Cosmetic Uses
Emla Cream manages pain and discomfort in medical and aesthetic settings. In medical contexts, it is commonly applied before needle-related procedures, such as routine blood draws, vaccinations, or IV catheter insertion. It also reduces pain during minor dermatological surgery, including wart removal, skin biopsies, and mole excisions.
The cream is a popular choice for cosmetic procedures that cause superficial pain. These uses include preparation for laser treatments, such as laser hair removal or tattoo removal, and certain types of microneedling. Patients also use it before cosmetic injections like dermal fillers to enhance comfort. The product is licensed for use on intact skin, providing temporary relief for procedures involving a brief, sharp sensation.
Safety Warnings and Adverse Effects
Most individuals experience transient, localized side effects at the application site. Common reactions include temporary skin pallor (blanching), redness (erythema), mild swelling (edema), or a mild burning, itching, or warming sensation. These effects typically subside quickly.
A serious risk associated with excessive or improper use is methemoglobinemia, a blood disorder that impairs oxygen delivery to the body’s tissues. This is primarily a concern when the cream is applied over large surface areas, left on too long, or used on young infants. Signs of this condition include bluish skin discoloration, light-headedness, and shortness of breath.
The cream is contraindicated for patients with a known allergy to amide-type anesthetics or those with a congenital form of methemoglobinemia. It should not be applied to broken skin, open wounds, or mucous membranes, as this significantly increases the risk of systemic absorption and toxicity.