Introduction of Lanolin

Lanolin is a complex mixture of high molecular weight esters, aliphatic alcohols, sterols, fatty acids, and hydrocarbons that has been widely used for centuries for its emollient properties.

Lanolin is similar in function to sebum that comes from sebaceous glands in the human skin. Sebum, like lanolin, acts to waterproof hair and skin. Because of its moisturizer or emollient (reducing water loss and itching) and antimicrobial actions, lanolin is used in personal care products, such as baby oil, diaper rash products, hemorrhoid medications, lip balm or salve for chapped lips, lotions and skin creams, medicated shampoos, makeup (lipstick, powder, foundation), nipple cream for lactating mothers, and shaving creams. Moreover, there are multiple industrial uses for lanolin including as a lubricant, leather production, textile additive as an emollient making textiles softer, in paints, varnishes, polishes, inks, and as waterproofing for concrete. Natural is not necessarily safe. The ingestion of lanolin leads to lanolin poisoning.

Allergic symptoms of Lanolin

Controversy as to lanolin's allergenicity began in the 1920s and remains an issue. The most appropriate patch test preparation(s) for detecting allergy remain disputed. Detection of lanolin-induced contact dermatitis in diseased skin by patch testing on normal skin may lead to false negative results. Patients with a positive patch test to lanolin may tolerate use of lanolin on normal skin.

Although lanolin is a weak sensitizer and the frequency of contact allergy to it in the European population reportedly is 0.4%, there are high-risk concomitant conditions: stasis dermatitis, leg ulcers, perianal/genital dermatitis, and atopic dermatitis (AD). Children and the elderly are also at greater risk of developing contact allergy to lanolin, partly because of comorbidities (AD and stasis dermatitis/leg ulcers, respectively). Finally, in the United States, non-Hispanic white patients are more likely than their non-Hispanic black counterparts to be lanolin allergic.

Diagnosis of Lanolin

The prevalence of lanolin contact allergy in dermatitis patients varies from 1.2% to 6.9%. Different lanolin derivatives are used in patch testing. To determine which combination of lanolin derivatives is most effective in patch testing for the diagnosis of lanolin contact allergy.

A retrospective analysis of patients patch tested between 2016 and 2017 was performed. Patients were eligible if they had been tested with lanolin alcohol 30% pet., Amerchol L101 50% pet., and a supplementary series containing other lanolin derivatives. Lanolin alcohol and Amerchol L101 were tested in duplicate.

Results Of 594 patients, 28.6% (95% confidence interval [CI]: 25.1%-32.3%) had a positive patch test reaction to at least one lanolin derivative. Reactions to lanolin alcohol (14.7%, 95%CI: 11.3%-18.2%) and Amerchol L101 (15.0%, 95%CI: 11.5%-18.5%) were common in the routinely tested series. Reactions to other test preparations were significantly less frequent (P < 0.05). The addition of Amerchol L101 to lanolin alcohol significantly increased the number of positive cases (odds ratio 1.79, P < 0.001).

The combination of lanolin alcohol and Amerchol L101 is effective in patch testing for the diagnosis of lanolin contact allergy. Routinely testing with other lanolin derivatives may not be worthwhile, as it detects only a few additional patients.

References:

[1] BLAIR A JENKINS  Donald V B. Lanolin.[J]. Dermatitis, 2023, 34 1: 4-12. DOI:10.1089/derm.2022.0002.

[2] JANNET KNIJP  Thomas R  Derk P Bruynzeel. Diagnosing lanolin contact allergy with lanolin alcohol and Amerchol L101[J]. Contact Dermatitis, 2019, 80 5: 298-303. DOI:10.1111/cod.13210.