This article is more than 5 years old. Information may no longer be current.

Ethyl-chloride spray administered prior to histamine skin-prick test significantly reduces pruritus

Patients treated with an ethyl-chloride spray before a histamine skin-prick test demonstrated significantly reduced pruritus intensity compared with those who received placebo, according to results of a prospective study.

“In addition, ethyl-chloride spray was free of adverse effects and did not reduce the wheal and flare reactions,” Amir Gal-Oz, MD, of Tel Aviv Sourasky Medical Center at Tel Aviv University in Israel, and colleagues wrote. “Taken together, our results suggest that ethyl-chloride spray may be ideal for prevention of pruritus secondary to allergy skin testing, without masking the skin-prick test results.”

Gal-Oz and colleagues performed a double blind, placebo-controlled study of 44 patients who underwent histamine skin-prick test on both arms. Prior to the skin-prick test, patients received a topical ethyl-chloride spray on one arm and a topical saline spray on the other arm to gauge pruritus intensity.

The researchers measured the wheal and flare reaction after the test. Patients reported the intensity of pruritus using a validated questionnaire that analyzed the itching sensation and severity. Investigators also used the visual analog scale.

The questionnaire had three indexes.

In the first index, patients were asked whether the pruritus sensation was tickling, stinging, stabbing, pinching, burning or crawling like ants. They rated the severity of those sensations from 0 to 3, with the highest number being most severe.

In the second index, patients were asked if the sensation was annoying, bothersome, worrisome or unbearable. They rated those feelings on the same 0-to-3 scale.

The third index summarized the first two index ranks.

For all indexes, ethyl-chloride spray significantly reduced pruritus when administered before the histamine skin-prick test. Results by index were as follows: first index, 3.7 ± 2.3 points for ethyl-chloride spray vs. 5 ± 3.5 points for placebo (P = .007); second index, 2.6 ± 2.1 points for ethyl-chloride spray vs. 3.8 ± 2.8 points for placebo (P = .002); third index, 6.3 ± 3.8 points for ethyl-chloride spray vs. 8.8 ± 5.8 points for placebo (P = .03).

The visual analog score was 3.7 ± 1.9 points for ethyl-chloride spray vs. 4.4 ± 2.3 points for placebo (P = .003).

Researchers reported no significant difference in wheal and flare reactions between the two treatments. – by Jeff Craven

Disclosure: The researchers report no relevant financial disclosures.