Background: Current evaluation of suspected allergic contact dermatitis to lanolin includes patch testing to lanolin alcohol (30% in petrolatum). Using this method, the prevalence of lanolin allergy is low (1.8%-2.5%).

Objective: The objective of this study was to determine whether patch testing to a single lanolin derivative results in underdiagnosis compared with patch testing to 12 lanolin derivatives.

Methods: Patients were prospectively patch tested to (1) lanolin alcohol (30% in petrolatum) in our standard allergen series; (2) Amerchol L101 (50% in petrolatum) in our cosmetic series; and (3) 10 lanolin derivatives (using concentrations and vehicles recommended in the literature) in a supplemental series.

Results: Of 286 patients, the overall prevalence of positive reactions to lanolin in at least 1 of the 3 patch test series was 6.29% (95% confidence interval [CI], 3.48%-9.11%) (n = 18). The prevalence rates of lanolin allergy using the standard, cosmetic, and supplemental series were 1.05% (95% CI, 0%-2.23%), 3.85% (95% CI, 1.62%-6.07%), and 3.85% (95% CI, 1.62%-6.07%), respectively. Amerchol L101 was associated with increased reaction rates compared with the standard (odds ratio, 3.81; P = 0.007) and supplemental (odds ratio, 8.85; P < 0.001) series, whereas reaction rates were similar for the standard and supplemental series (P = 0.78).

Conclusions: Amerchol L101 and patients' own products should be added to a standard patch testing allergen series to adequately identify lanolin allergy.