Hand, Foot, and...Lidocaine?

by Nicholas Otts, MD

Edited by Gal Altberg, MD

A Common Problem:

3 year old male presents w/ decreased oral intake associated w/ ulcerative and vesicular lesions in his mouth and irritability. Normal amount of wet diapers, no signs of dehydration on exam. Vesicular lesions on palms and soles as well.

(https://www.shutterstock.com/image-vector/hand-foot-mouth-disease-hfmd-illustration-265246085)

To give or not to give viscous lidocaine in an attempt to increase oral intake in a patient you do not wish to admit?

A Small Dose of EBM:

Treating pediatric viral stomatitis is a challenge. The primary goal is to avoid dehydration, and thus, admission for a primarily viral problem that will resolve with time. Oral medications commonly attempted in the ED include diphenyhydramine, coating agents (maalox), and viscous lidocaine (including combinations). For years, much of the EBM supporting either was case based and anecdotal. The desire to do something for these patients and their suffering parents is strong.

(http://njmommyblog.com/coxsackie-hand-foot-mouth-disease-signs-symptoms-survival/)

The most potentially toxic (1,2) but also potentially helpful medication is lidocaine.  Thankfully, a recent blinded, randomized, placebo-controlled trial examined this exact question (3).

In 2014, a trial out of Australia tested 2% viscous lidocaine against a placebo with improved oral intake after one hour as the primary outcome measure. The study had a good design and was powered appropriately.

In the end, however, the oral intake in both groups was not significantly different. Viscous lidocaine appeared to make no difference for all of the measured outcomes. Further, because viscous lidocaine has the most potential to cause harm out of the agents frequently used, it is a less than desirable choice.

(http://www.babyinfo.com.au/newborns-and-infants/understanding-hand-foot-and-mouth-disease)

Because  both the placebo and lidocaine groups in general showed significant improvement in oral intake as compared to the reported oral intake at home, it is suggested that simply the attention and instruction by the ED staff to the parents contributed significantly to the better outcomes.

This is a good trial, but there are some problems.  First, as pointed out by the famous NYC toxicologist Dr. Hoffman in a letter to the editor in response to the article (4), the trial did not account for pain at all as an outcome measure.  One can only use this trial to say that lidocaine did not improve oral intake, not that it does not relieve pain.

Further, the study only accounted for the first hour of oral intake post administration, and a longer term benefit of lidocaine was not assessed (but the timing was applicable to standard emergency department goals of disposition in these types of patients).

Bottom line: right now, due to potential for toxicity and no proven benefit in increasing oral intake, lidocaine may not be the best option for ulcerative lesions in the mouth. Good instruction to the parents and bringing attention to the issue of dehydration, however, may make all the difference.

References:

1. Hess GP, Walson PD. Seizures secondary to oral viscous lidocaine. Ann Emerg Med. 1988; 17(7) 725.

2. Questions and Answers: Reports of  rare, but potentially serious and potentially fatal adverse effect with the use of OTC benzocaine gels and liquids applied to gums or mouth. www.fda.gov/Drugs/DrugSafety/ucm250029.htm

3. Hopper SM, McCarthy M, Tancharoen C, et al. Topical Lidocaine to improve oral intake in children and painful infectious mouth ulcers: a blinded, randomized, placebo-controlled trial. Ann Emerg Med. 2014; 63: 292-299.

4. Hoffman R. Viscous Lidocaine Treatment for Painful Oral Infections in Children: Disappointingly Dismissive of Pediatric Pain. http://dx.doi.org/10.1016/j.annemergmed.2014.02.026