The phenomenon of lanolin allergenicity is the focus of the Contact Allergen of the Year article in Dermatitis. 

Lanolin and its derivatives are widely used in cosmetics and pharmaceuticals designed for topical use on skin, lips, nails, and hair, and as an ocular emollient. They also have many industrial uses. Still, lanolin’s allergenicity remains controversial, and appropriate patch testing to detect lanolin allergy remains a topic of dispute.

Study authors Blair Jenkins, MD, PhD and Donald Belsito, MD, MBA, from Columbia University Irving Medical Center, found that 0.4% of people in the general population have lanolin allergy. Although they describe lanolin as a “weak sensitizer,” they identify special populations for which the concern for lanolin allergy may be greater. These include people with stasis dermatitis/chronic venous insufficiency, chronic leg ulcer, or perianal and genital dermatitis, patients with atopic dermatitis, children, and the elderly.  In the U.S., non-Hispanic white patients are more likely than their non-Hispanic black counterparts to be lanolin allergic.

There is no single patch test preparation to accurately assess “lanolin” allergy, they write. "However, since the principal allergens in “lanolin” are the free alcohols industrial and academic researchers interested in lanolin allergy need to undertake an analysis of our current patch test materials for the presence of these, and other potentially allergenic substances (e.g., low molecular weight oxidized organic derivatives formed during different manufacturing processes),” they wrote. “These studies may well lead to the introduction of newer patch test preparations with improved specificity and sensitivity for detecting “lanolin” allergy.”

“Detection of lanolin allergy by patch testing is challenging because ‘allergic’ patients may tolerate lanolin on healthy skin yet develop contact dermatitis when products containing lanolin are used on inflamed skin,” agrees  Editor-in-Chief of Dermatitis Anthony Gaspari, MD, from the Sidney Kimmel Medical College of Thomas Jefferson University in a news release. “This article succinctly describes the properties of this fascinating allergen and the challenges of confirming the diagnosis of lanolin allergy.”