Clinical relevance of positive patch test reactions to lanolin: A ROAT study

Background: Lanolin is often included when patch testing for common contact allergens. The clinical relevance of a positive patch test reaction to lanolin markers is, however, still a subject for debate. Objectives: To evaluate Amerchol L101 as a marker of lanolin allergy and investigate the clinical impact of lanolin-containing moisturizers on healthy and damaged skin using the repeated open application test (ROAT). Methods: Twelve test subjects and 14 controls were patch tested with Amerchol L 101 and additional lanolin markers. Subsequently, a blinded ROAT was performed on the arms of the study participants for 4 weeks. Each participant applied a lanolin-free cream base and two different lanolin-containing test creams twice daily on one arm with intact skin and on the other arm with irritant dermatitis, induced by sodium lauryl sulfate (SLS). Results: Eleven test subjects (92%) had positive patch test reactions to Amerchol L 101 when retested and one test subject (8%) had a doubtful reaction. None of the study participants had any skin reactions to the ROAT on intact skin and all participants healed during the ROAT on damaged skin. Conclusions: Lanolin-containing emollients do not cause or worsen existing dermatitis when performing ROAT in volunteers patch test positive to Amerchol L101.