FDA: Mammo topical anesthetics may have life-threatening side effects
Lidocaine gel, a topical anesthetic, to the skin to decrease discomfort during mammography. Image Source: www.pantagraph.com
The FDA has issued a public health advisory to alert consumers, patients and healthcare professionals about potentially serious and life-threatening side effects from the improper use of topical anesthetics that are available in over-the-counter and prescription forms.

Topical anesthetics contain anesthetic drugs, such as lidocaine, tetracaine, benzocaine and prilocaine in a cream, ointment or gel. When applied to the skin surface, they can be absorbed into the blood stream and, if used improperly, may cause life-threatening side effects, such as irregular heartbeat, seizures, breathing difficulties, coma or even death, according to the FDA.

The agency said it has received reports of adverse events and deaths of two women who used topical anesthetics before laser hair removal. 

The FDA strongly advises consumers not to:
  • Make heavy application of topical anesthetic products over large areas of skin;
  • Use formulations that are stronger or more concentrated than necessary;
  • Apply these products to irritated or broken skin;
  • Wrap the treated skin with plastic wrap or other dressings; and
  • Apply heat from a heating pad to skin treated with the products.

When skin temperature increases, the agency said that the amount of anesthetic reaching the blood stream is unpredictable and the risk of life-threatening side effects increases with greater amounts of lidocaine in the blood.

A study recently published in Radiology examined women taking acetaminophen and ibuprofen by mouth versus applying lidocaine gel, a topical anesthetic, to the skin to decrease discomfort during mammography. The lidocaine gel was applied to a wide skin surface area and then covered with plastic wrap. There were no serious or life-threatening side effects reported in the study, nor were any reported when FDA discussed the results with the doctor who performed the study. The study results favored the use of lidocaine as there was significantly less discomfort than with the plain gel or oral acetaminophen or ibuprofen. 

However, given the life-threatening side effects associated with the use of topical anesthetics during laser hair removal, the FDA said it is concerned that similar side effects could occur when topical anesthetics are used during mammography. Further, the agency noted that the study was small and it is possible that a larger study might show different findings. Therefore, they said that patients should talk with their healthcare professional if they are considering using a topical anesthetic before a mammogram.