Q:

5/21/2013
The mother of a 5 year old child who was afraid of shots called us. She wanted to know if we could spray the child's skin with a medication that would numb the site of allergy tests and allergy shots. The pediatrician uses a spray before vaccinations. The doctor and I were afraid such a spray would affect the results of our allergy tests or the site of our allergy shots. We would like to know if you have any information on such a spray and its effects.

A:

Thank you for your inquiry.

Copied below are abstracts dealing with two measures that can be utilized to diminish the pain associated with skin tests. One discusses the application of a topical anesthetic, and the other discusses the use of an ethyl chloride spray.

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 SH, Eggleston PA.
Source
Department 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.

Ann Allergy Asthma Immunol. 2005 Aug;95(2):149-53.
Effect of topical vapocoolant spray on skin test wheal, flare, and pain responses.
Waibel KH, Katial RK.
Source
Allergy and Immunology Service, Department of Medicine, Dwight D. Eisenhower Army Medical Center, Fort Gordon, Georgia, 30905-5650, USA.
Abstract
Background: Skin puncture and intradermal tests are commonly used to evaluate allergic rhinitis. Ethyl chloride, a topical vapocoolant spray, provides skin analgesia before venipuncture, but it has not been studied with allergy skin testing.
Objective: To determine the effects of ethyl chloride vs placebo on skin puncture testing (SPT) and intradermal allergy testing.
Methods: We enrolled 20 healthy adults with a history of positive aeroallergen skin test results in a randomized, double-masked, placebo-controlled study. Ethyl chloride and placebo sprays were randomly placed on the upper back. Paired SPT was performed with saline, histamine, and standardized aeroallergens, including Bermuda grass, Kentucky blue grass, timothy grass, cat, Dermatophagoides pteronyssinus, and Dermatophagoides farinae. Serial dilutional end-point intradermal tests were then performed using 1 standardized aeroallergen. Wheal and flare areas were outlined, scanned, and digitally measured. Participants used a 10-cm visual analog scale to record pain during skin testing.
Results: Eighteen individuals completed the study. Compared with placebo, ethyl chloride had no significant effect on histamine wheal (P = .53), histamine flare (P = .39), aeroallergen wheal (P = .10), or aeroallergen flare (P = .71) area for SPT. Serial dilutional end-point intradermal testing was similar after ethyl chloride and placebo application (P = .75). Mean pain scores for SPT were improved with ethyl chloride compared with paired placebo skin tests, although pain scores did not reach significance for SPT (P = .21) or intradermal testing (P = .87).
Conclusions: Ethyl chloride does not significantly reduce histamine and aeroallergen wheal and flare areas during SPT and intradermal allergy skin testing. Ethyl chloride, vs placebo, reduced pain in some individuals during skin testing, although this did not attain statistical significance.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology