The U.S. Food and Drug Administration recently issued an advisory, reminding the public about the risks of using skin numbing products for relieving pain from medical tests and conditions.

 Specifically, the FDA pointed out the potential hazards of administering the topical anesthetic known as lidocaine. The administration instructed patients to speak with their physician if they are considering using a topical anesthetic before a mammogram.

 During a study, lidocaine was spread over a wide area and covered with plastic wrap.

 “Although no serious side effects were reported in this study, it was not large enough to evaluate whether uncommon but serious reactions could occur with this use,” the FDA stated. “FDA remains concerned about the potential for topical anesthetics to cause serious and life threatening adverse effects when applied to a large area of skin or when the area of application is covered.”

 These side effects can include irregular heartbeat, seizures, breathing difficulties, coma, and even death.

 The FDA noted that when used appropriately, topical anesthetics may provide safe and effective pain relief. Doctors should determine whether pain relief can be achieved safely with a topical anesthetic or if they should turn to a different treatment that may be more appropriate.

If the topical anesthetic is selected, then doctors should prescribe the lowest necessary amount, the FDA said.

 In February 2007, the FDA issued a Public Health Advisory: Life-Threatening Side Effects with the use of Skin Products Containing Numbing Ingredients for Cosmetic Procedures, which described the deaths of two women who used topical anesthetics prior to laser hair removal.