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Cox NH, Forsyth A. Thimerosal allergy and vaccination reactions. Contact Dermatitis 1988;18:229-233.

http://www.fda.gov/cber/vaccine/thimerosal.htm

Mercury Allergy and Patch Testing
Ernst Epstein, MD
San Mateo, Calif
Arch Dermatol. 1974;109(1):98.

In a study by Baer et al1 mercury allergy was found in 22% of a large number of patients tested with a series of routine patch tests, as reported in the July ARCHIVES. Baer et al point out that this percentage is far higher than the incidence of clinical mercury allergy among eczematous patients. They attribute the lack of correlation between patch tests with mercury and mercury allergy to “low degrees of sensitization in many individuals.”
While such an explanation is possible, it is much more likely that the numerous positive tests represent weak, false-positive irritant reactions. The authors consider this possibility, and rather surprisingly dismiss it, stating the following:
We consider it unlikely that a significant proportion of these reactions were due to primary irritancy of the test material since the tests were carried out with 0.05% mercury bichloride solution rather than with the 0.1%

http://archderm.ama-assn.org/cgi/content/summary/109/1/98

van Ketel, W.G. and C.G. Roeleveld, A curious case of allergy to mercuric compounds. Contact Dermatitis, 1977. 3(2): p. 106.

http://www.dermacom.ch/private/alindex/ME010.htm

To date, the most common vaccine-associated adverse event to which thimerosal has been possibly implicated is minor, contact allergy (delayed-type hypersensitivity) skin reactions(9,29). Between 1% and 16% of tested individuals have exhibited such a reaction on skin patch testing(30).
Immediate hypersensitivity (e.g., anaphylaxis) and immune complex-mediated disorders (e.g., glomerulonephritis) have been reported in association with exposure to thimerosal-containing products although it is uncertain if thimerosal was the responsible allergen(14,29).

Canada Communicable Disease Report
Volume 28-09
1 May 2002

http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/02vol28/dr2809ea.html

Wattanakrai P, Rajatanavin N.
Division of Dermatology, Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.

BACKGROUND: Thimerosal or merthiolate is used as an antiseptic and a preservative in topical medicaments, cosmetics, and vaccines. Thimerosal is known to cause delayed type hypersensitivity. However, there is argument about the clinical relevance and risk of using thimerosal-preserved products in thimerosal allergic individuals. OBJECTIVE: Retrospective review of patch test results from the Ramathibodi Hospital patch test clinic to determine the prevalence and relevance of allergic reactions to thimerosal in Thailand. MATERIAL AND METHOD: During a 5-year period, thimerosal was patch tested in all patients tested for possible allergic contact dermatitis. Thimerosal was the second most common allergen causing a positive patch test reaction. RESULTS: Of the 433 patients tested, 46 (10.62%) were positive to thimerosal. However, despite the high prevalence of positive reactions none was clinically relevant to their present dermatitis, none of the patients reported reactions to vaccination or cross-reaction to piroxicam. CONCLUSION: There was a high rate of sensitization to thimerosal in Thai patients, but were of little clinical relevance. The author does not advise thimerosal allergic individuals to avoid vaccination, although the small risk of local dermatitis should be pointed out. The topical use of thimerosal containing antiseptics should be avoided.

1: J Med Assoc Thai. 2007 Sep;90(9):1775-9
PMID: 17957918 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/pubmed/17957918