Effect of topical vapocoolant spray on skin test wheal, flare, and pain responses

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.

To determine the effects of ethyl chloride vs placebo on skin puncture testing (SPT) and intradermal allergy testing.

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.

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).

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.