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 though is 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 by 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 one arm with irritant dermatitis, induced by sodium lauryl sulphate (SLS).

Results: Eleven test subject (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 for 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. This article is protected by copyright. All rights reserved.

Keywords: Allergic Contact Dermatitis; Amerchol L101; CAS no. 8027-33-6; Lanolin; Patch testing; ROAT; emollient; relevance; repeated open application test.