Used for thousands of years for its emollient qualities, and for hundreds of years as an ingredient in skin care ointments, lanolin is a greasy yellow substance derived from the sebaceous secretions of sheep, as well as other wool-bearing animals (Br. J. Nurs. 2009:54-7). Although a plant-derived substitute has been recently produced, lanolin itself is a complex natural product that cannot be synthesized. It is also a commonly used occlusive ingredient, along with products or compounds such as paraffin, squalene, dimethicone, soybean oil, grapeseed oil, propylene glycol, and beeswax (Atlas of Cosmetic Dermatology, edited by Z. Draelos. New York: Churchill Livingstone, 2000, p. 83).
Photo courtesy USDA
Lanolin, a substance derived from the sebaceous secretions of sheep, is an effective occlusive and emollient agent, but has been known to cause contact sensitization in some individuals.
Lanolin, like mineral oil and petrolatum, is known for it dual activity, exerting both occlusive and emollient effects. This column will briefly review the current status and reputation of lanolin as a cutaneous therapeutic agent.
Evidence of Contact Sensitization. Lanolin shares two important features with stratum corneum lipids: Lanolin contains cholesterol, an essential constituent of stratum corneum lipids; and lanolin and stratum corneum lipids can coexist as solids and liquids at physiologic temperatures. Not surprisingly, given its longtime use as an adjuvant, lanolin is characterized by a very different composition from human sebum. This is also the case for commercial lanolin products. Significantly, the method used to refine the compound determines the quality and composition of the resulting formulation; therefore, not all lanolin products exhibit the same activity (Dry Skin and Moisturizers, edited by M. Loden and H. Maibach. Boca Raton: CRC Press, 2000, p. 259).
Unfortunately, a small percentage of individuals who use lanolin develop contact sensitization to the occlusive/emollient agent. Consequently, lanolin has developed a reputation as a sensitizer that, according to some, may be undeserved (Contact Dermatitis 1998;39:103-7; Br. J. Nurs. 2000;26:54-7). Nevertheless, manufacturers have responded to such claims, and many moisturizing products are now touted as "lanolin free."
Another response to the notion that lanolin provokes allergic reactions has spurred the development of ultrapure, hypoallergenic, medical-grade lanolin formulations such as Medilan. In fact, Medilan has been shown to provoke virtually no sensitization (Br. J. Nurs. 2000;26;54-7). In addition to the soothing, healing properties imparted by Medilan, it is also effective as an occlusive agent and has exhibited the capacity to penetrate the skin and assist in stratum corneum water retention.
In 2008, investigators sought to identify the frequency of positive patch test reactions to common allergens in leg ulcer or venous disease patients by using a case series of 100 consecutive consenting subjects who had chronic venous disease and other leg ulcer etiologies. At least one positive patch test was observed in 46% of patients, with multiple reactions in the same subject frequently seen. Of the 38 common allergens tested, lanolin was identified among the most frequent sensitizers, which also included fragrances, antibacterial agents, and rubber-related compounds (Int. J. Low. Extrem. Wounds 2008;7:120-5). Of course, such results suggest that lanolin may be contraindicated in patients with leg ulcers, but are not generalizable to a healthy population.
Use in Nipple Crack and Xerosis. In 2003, Dodd and Chalmers led a multicenter, prospective, randomized controlled clinical trial to compare the effects of hydrogel dressings to lanolin ointment for the prevention and treatment of nipple soreness in 106 lactating mothers. A board-certified lactation specialist provided breastfeeding guidance at the beginning of the study. During the first 12 days of the study, participants, who were randomized to either of the two groups, were instructed to rate pain intensity according to a numeric scale as well as a verbal description scale. Patients then forwarded self-reported skin assessments of the bilateral breasts, nipples, and areolae to investigators.
A significantly greater reduction in pain score mean values was identified in the hydrogel group at baseline, day 10, and day 12, compared with the lanolin group, and the hydrogel group discontinued treatment earlier than did the participants using lanolin. Overall, researchers found hydrogel to be superior to lanolin ointment for the management of nipple soreness (J. Obstet. Gynecol. Neonatal Nurs. 2003;32:486-94).
Additional evidence that lanolin is not the optimal therapeutic option for sore or cracked nipples came 4 years later, when investigators conducted a randomized, double-blind clinical trial to compare a peppermint gel formulation, modified lanolin, and a placebo control ointment for the treatment of nipple crack related to breastfeeding. A total of 216 primiparous mothers were randomly assigned to the three groups, which were comparable in mean age, and were instructed to apply their selected formulation on both breasts for 14 days. Patients were seen for up to four follow-up visits, as well as a final visit at week 6. Researchers found that nipple and areola cracks were less frequent in the peppermint gel group than in the lanolin group or placebo group (Med. Sci. Monit. 2007;13:CR406-11).