Q:

6/11/2014
I have several patients request topical lidocaine to be applied to their skin prior to percutaneous skin prick testing. Apparently there is a local practitioner in my area who does this, presumably prior to intradermal testing (possibly prior to percutaneous as well). I do not allow this myself as I question how topical lidocaine would affect mast cell response. Additionally, we try to explain to the patients that percutaneous testing has minimal pain and we typically do not encounter issues after this discussion. Have you heard of doing this and do you know of any evidence for or against it?

A:

Thank you for your inquiry.

The abstract copied below represents, in my opinion, the best data we have regarding the use of lidocaine to create analgesia during skin tests. Based upon the information we have, it may be used with minimal if any effect on the skin test. I have never personally employed lidocaine but have encountered several practices that do use it during skin testing.

Thank you again for your inquiry and we hope this response is helpful to you.

Ann Allergy Asthma Immunol. 1997 Jan;78(1):64-8.
EMLA cream for pain reduction in diagnostic allergy skin testing: effects on wheal and flare responses.
Sicherer SH1, Eggleston PA.
Author information
1Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Abstract
Background: The use of a topical anesthetic cream containing prilocaine and lidocaine (EMLA) has been considered to reduce the pain of diagnostic allergy skin testing, but the effects of the cream on interpretation of skin tests is unclear.
Objective: To determine the effects of the cream for pain reduction using prick and ID skin tests and for possible alteration of wheal and flare responses to allergen, saline, and histamine.
Methods: In a randomized, double-masked, placebo-controlled design, 20 adult volunteers with a history of positive allergen tests had EMLA and placebo cream placed according to the manufacturer's recommendations on the volar aspect of the arms. Paired skin tests were placed and subjects rated the tests on a pain scale from 0 to 5 and average wheal and flare diameters were determined.
Results: Mean pain scores (+/-SEM) were significantly reduced from 2.5 +/- 0.7 to 1.1 +/- 0.6 for prick tests (n = 20, P < .001) and from 3.2 +/- 0.9 to 1.13 +/- 0.9 for intradermal (ID) tests (n = 58, P < .001). The wheal sizes for allergen prick tests, allergen ID tests, and histamine ID tests were identical in comparing placebo to EMLA-treated skin. Flare responses were reduced on the actively treated skin, on average, as follows: allergen skin tests- 52% (P < .001), and histamine- 40% (P < .001). In nine tests there was complete suppression of the flare response, all on the EMLA treated skin.
Conclusions: EMLA significantly reduced the pain associated with diagnostic allergy skin testing and with no effect on the size of the wheal response. It reduces the flare response, in some cases inhibiting it completely, which must be taken into consideration in interpreting results.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology