Side Effects of EMLA (lidocaine and prilocaine)

EMLA (lidocaine and prilocaine) is a topical anesthetic cream used as a local anesthetic on normal intact skin and genital mucous areas, before minor procedures.

EMLA enters through the skin and blocks pain receptors in nerve endings. EMLA reduces conduction of nerve impulses by interrupting the transfer of sodium ions across the membranes of nerve cells. This results in a local anesthetic action. 

Common side effects of EMLA include

• application site redness,
• pain,
• burning,
• paleness,
• swelling, and
• altered temperature sensation.

Serious and rare side effects of EMLA include

• shock,
• central nervous system depression,
• hypersensitivity reactions, and
• low blood pressure (hypotension).

Drug interactions of EMLA include anti-arrhythmic drugs such as tocainide and mexiletine due to additive effects on heart rate and rhythm.

• EMLA should be used with caution with anti-arrhythmic drugs like amiodarone, sotalol, bretylium, and dofetilide because of increased risk developing abnormal heart rate and rhythm.
• Prilocaine may contribute to formation of methemoglobin in patients treated with other drugs known to cause methemoglobinemia.

There are no adequate studies of EMLA to determine safe and effective use in pregnant women. EMLA may be excreted in breast milk; therefore, caution should be exercised before using them in breastfeeding mothers.

Common side effects of lidocaine and prilocaine are:

• application site redness,
• pain,
• burning,
• paleness,
• edema, and
• altered temperature sensation.

Other rare side effects include:

• shock,
• central nervous system depression,
• hypersensitivity reactions, and
• hypotension (low blood pressure).

Localized Reactions

During or immediately after treatment with EMLA Cream on intact skin, the skin at the site of treatment may develop erythema or edema or may be the locus of abnormal sensation. Rare cases of discrete purpuric or petechial reactions at the application site have been reported. Rare cases of hyperpigmentation following the use of EMLA Cream have been reported.

The relationship to EMLA Cream or the underlying procedure has not been established. In clinical studies on intact skin involving over 1,300 EMLA Cream-treated subjects, one or more such local reactions were noted in 56% of patients, and were generally mild and transient, resolving spontaneously within 1 or 2 hours. There were no serious reactions that were ascribed to EMLA Cream.

Two recent reports describe blistering on the foreskin in neonates about to undergo circumcision. Both neonates received 1.0 g of EMLA Cream.

In patients treated with EMLA Cream on intact skin, local effects observed in the trials included:

• paleness (pallor or blanching) 37%,
• redness (erythema) 30%,
• alterations in temperature sensations 7%,
• edema 6%,
• itching 2% and rash,
• less than 1%.

In clinical studies on genital mucous membranes involving 378 EMLA Cream-treated patients, one or more application site reactions, usually mild and transient, were noted in 41% of patients.

The most common application site reactions were

• redness (21%),
• burning sensation (17%) and
• edema (10%).

Allergic Reactions

• Allergic and anaphylactoid reactions associated with lidocaine or prilocaine can occur.
• They are characterized by
  • urticaria,
  • angioedema,
  • bronchospasm, and
  • shock.
• If they occur they should be managed by conventional means. The detection of sensitivity by skin testing is of doubtful value.

Systemic (Dose Related) Reactions

Systemic adverse reactions following appropriate use of EMLA Cream are unlikely due to the small dose absorbed. Systemic adverse effects of lidocaine and/or prilocaine are similar in nature to those observed with other amide local anesthetic agents including CNS excitation and/or depression (lightheadedness, nervousness, apprehension, euphoria, confusion, dizziness, drowsiness, tinnitus, blurred or double vision, vomiting, sensations of heat, cold or numbness, twitching, tremors, convulsions, unconsciousness, respiratory depression and arrest).

Excitatory CNS reactions may be brief or not occur at all, in which case the first manifestation may be drowsiness merging into unconsciousness. Cardiovascular manifestations may include bradycardia, hypotension and cardiovascular collapse leading to arrest.

EMLA Cream should be used with caution in patients receiving Class I antiarrhythmic drugs (such as tocainide and mexiletine) since the toxic effects are additive and potentially synergistic.

Patients who are administered local anesthetics are at increased risk of developing methemoglobinemia when concurrently exposed to the following drugs, which could include other local anesthetics:

Examples of Drugs Associated with Methemoglobinemia:

Specific interaction studies with lidocaine/prilocaine and class III anti-arrhythmic drugs (e.g., amiodarone, bretylium, sotalol, dofetilide) have not been performed, but caution is advised.

Should EMLA Cream be used concomitantly with other products containing lidocaine and/or prilocaine, cumulative doses from all formulations must be considered.