Patch-test reactions to topical anesthetics: retrospective analysis of cross-sectional data, 2001 to 2004.
BACKGROUND
Allergy to topical anesthetics is not uncommon. The cross-reactivity among topical anesthetics and the screening value of benzocaine alone are not well understood.


OBJECTIVE
The goals for this study were: (1) to evaluate the frequency and pattern of allergic patch-test reactions to topical anesthetics, using North American Contact Dermatitis Group (NACDG) data, and (2) to compare these results to allergen frequencies from other published studies.


METHODS
The NACDG patch-tested 10,061 patients between 2001 and 2004. In this analysis patients were included who had positive patch-test reactions to one or more of the following: benzocaine, lidocaine, dibucaine, tetracaine, and prilocaine.


RESULTS
Of patch-tested patients, 344 (3.4%) had an allergic reaction to at least one anesthetic. Of those, 320 (93.0%) had an allergic reaction to only one topical anesthetic. Overall, reactions to benzocaine (50.0%, 172 of 344) were most prevalent, followed by reactions to dibucaine (27.9%, 96 of 344); however, reactions to dibucaine were significantly more frequent in Canada than in the United States (relative risk [RR], 2.31; 95% confidence interval [CI], 1.67-3.20; p < .0001). Of patients reacting to more than one anesthetic, most (79%, 19 of 24) reacted to both an amide and an ester.


CONCLUSIONS
Of the topical anesthetics tested, benzocaine was the most frequent allergen overall. Over 50% of allergic reactions to topical anesthetics in this study would have been missed had benzocaine been used as a single screening agent. Cross-reactivity patterns were not consistent with structural groups.
Warshaw
Erin M
EM
Schram
Sarah E
SE
Belsito
Donald V
DV
DeLeo
Vincent A
VA
Fowler
Joseph F
JF
Maibach
Howard I
HI
Marks
James G
JG
Mathias
C G Toby
CG
Pratt
Melanie D
MD
Rietschel
Robert L
RL
Sasseville
Denis
D
Storrs
Frances J
FJ
Taylor
James S
JS
Zug
Kathryn A
KA
D000287:Administration, Topical; D000779:Anesthetics, Local / Q000009:adverse effects*; D001566:Benzocaine / Q000009:adverse effects; D002170:Canada / Q000453:epidemiology; D003430:Cross-Sectional Studies; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D003992:Dibucaine / Q000009:adverse effects; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D011237:Predictive Value of Tests; D011318:Prilocaine / Q000009:adverse effects; D012189:Retrospective Studies; D012307:Risk Factors; D013748:Tetracaine / Q000009:adverse effects; D014481:United States / Q000453:epidemiology
D000779:Anesthetics, Local; D011318:Prilocaine; D013748:Tetracaine; D008012:Lidocaine; D003992:Dibucaine; D001566:Benzocaine