Published: May 2009

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Adverse reactions to topical anaesthetics

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Prescriber Update 30(2): 10
May 2009

Medsafe has recently been made aware of serious adverse reactions resulting from improper use of topical anaesthetics such as lidocaine, amethocaine and prilocaine.

In January 2009, the Food and Drug Administration (FDA) issued a public health advisory about the improper use of topical anaesthetics. This advisory followed reports of adverse events and the deaths of two women who used topical anaesthetics prior to laser hair removal procedures. Both cases involved the use of high concentrations of topical anaesthetic over large areas of the body.

In addition, other international regulatory agencies have also received reports of serious adverse reactions such as methaemoglobinaemia, irregular heartbeat, seizures, coma and breathing difficulties. These reactions have been reported in adults and children when administered for both approved and unapproved indications.

Prescribers are reminded of the following:

• If a topical anaesthetic is required the lowest possible dose should be used.
• Topical anaesthetics should not be applied to irritated or broken skin.
• Children should be monitored during and after the use of topical anaesthetics as they may be at greater risk of experiencing adverse reactions than adults.

Patients who use topical anaesthetics on large areas of their body, or use occlusive wraps or dressings to enhance the effects of topical anaesthetics are more likely to experience serious adverse reactions.