Lanolin: a classic moisturizer some skin can’t tolerate

Lanolin has been softening human skin for well over a century, long before anyone talked about skin barriers. It’s in lip balms, cracked-heel ointments, nipple creams, diaper creams and old-fashioned hand salves, and it works. It’s also the ingredient the American Contact Dermatitis Society picked as its Allergen of the Year in 2023, which sounds alarming until you read why. Here’s the full picture.

Where lanolin comes from

Lanolin is the waxy substance sheep secrete from their skin to coat their wool. It’s what lets rain run off a fleece. After shearing, the wool is washed, the grease is separated out, and it’s refined into the pale yellow, sticky wax you find in a tub of ointment. No animal is harmed in the process; the sheep just get a haircut.

Chemically, lanolin is a complex mixture. DermNet describes it as more than 80% high-molecular-weight esters, along with fatty alcohols, sterols, fatty acids and hydrocarbons. That composition is close enough to the oily film on human skin that lanolin blends in rather than sitting on top.

Why it’s such a good moisturizer

Lanolin does two jobs at once. It’s an emollient, meaning it smooths and softens rough skin by filling gaps between the flakes on the surface. And it’s an occlusive, meaning it slows water from evaporating out of the skin.

The 2023 Cutis review of lanolin notes that it can hold as much as twice its weight in water and may reduce transepidermal water loss (the water constantly evaporating through your skin) by 20 to 30%. It also points out that lanolin “maintains tissue breathability”, which is one reason it has been used on wounds and cracked skin: it protects without sealing.

That combination is why lanolin turns up in balms and ointments for the driest, most damaged spots: lips, heels, knuckles, nipples, and the skin under a diaper. In a Canadian winter, when indoor heating and outdoor cold strip moisture from your hands, a lanolin-based salve is a classic remedy.

Who reacts to it, and how often

Now the other side. Some people develop contact allergy to lanolin: a delayed immune reaction, showing up as an itchy rash a day or two after the product goes on. It’s diagnosed with patch tests, where small amounts of suspected allergens are taped to the back.

The numbers depend on who you test. Among people referred for patch testing because they already have a rash, DermNet gives a positive rate of 1.7 to 3.3%, and the North American Contact Dermatitis Group found 3.3% of more than 43,000 patients tested between 2001 and 2018 reacted to one of the two standard lanolin markers. In the general population, it’s far lower: a European study of over 3,000 people found 0.4%.

Lanolin is a weak sensitizer. It rarely causes allergy on healthy skin. The risk climbs when the skin barrier is already broken and lanolin is applied often. The 2023 Dermatitis review by Jenkins and Belsito lists four high-risk groups:

• People with stasis dermatitis (eczema on the lower legs caused by poor vein circulation)
• People with chronic leg ulcers
• People with atopic dermatitis (the common form of eczema)
• People with perianal or genital dermatitis

Because leg ulcers and stasis eczema cluster in older adults, and atopic dermatitis in children, those two age groups show higher rates too. The explanation is straightforward: damaged skin lets more allergen through, and people with chronic skin problems use more creams, more often, on skin that’s already inflamed.

The lanolin paradox

Dermatologists have argued about lanolin for a hundred years, and the argument has a name. In 1996, a dermatologist named Wolf described the “lanolin paradox”, modelled on the earlier paraben paradox. Its main points: lanolin generally doesn’t cause allergy in everyday personal care products but can in medicated creams on damaged skin; some patients who react on inflamed skin can use lanolin products on healthy skin without trouble; and patch tests on normal skin can miss an allergy that only shows up on diseased skin.

The Allergen of the Year designation was partly about drawing attention to that confusion. A 2020 study in Contact Dermatitis took a dozen volunteers who had tested positive to the standard lanolin marker and had them apply lanolin-containing creams twice a day for four weeks, on both healthy skin and skin with a deliberately induced irritant rash. None of them reacted, and 75 of 78 test sites had healed by the end. The authors concluded that lanolin emollients “do not cause or worsen existing dermatitis” in those volunteers and urged caution before telling people to avoid lanolin on the strength of a patch test alone.

So a positive patch test is a reason to be careful, not necessarily a life sentence. If you’ve tested positive, the Cutis review suggests a repeat open application test: apply the specific product to a small patch of unaffected skin on the inner forearm twice a day for at least 10 days. If nothing happens, you’re unlikely to be allergic to that product. Do this with your dermatologist’s guidance rather than on a flaring rash.

What “medical grade” or “highly purified” lanolin means

The allergenic part of lanolin is the free wool alcohols, not the esters that make up most of it. Purification of crude lanolin began in 1882 and has been refined ever since; the newest highly purified anhydrous lanolins contain very little free alcohol. That’s what “medical grade” or “highly purified” on a label refers to.

Highly purified lanolin is what’s used in nipple creams and in ointments meant for broken skin. It doesn’t eliminate allergy risk, and someone with a confirmed lanolin allergy should still avoid it, but it’s a meaningfully different material from the crude wool grease of a century ago.

Sore nipples: what the trials say

The best-known use of lanolin today is on sore nipples in the early weeks of breastfeeding, and the research is honestly mixed. A 2014 Cochrane review pooled four trials with 656 women and found “insufficient evidence” that lanolin, with or without breast shells, improved pain more than applying nothing or expressed breast milk. It also noted that for most women pain settles to mild by about seven to ten days no matter what they use, and rated the evidence low quality.

A 2018 randomized trial in Brazil of 180 women compared highly purified lanolin with expressed breast milk over seven days. The lanolin group reported more pain improvement, and nipple trauma improved in 29.5% of them versus 15.6% in the breast milk group. Both groups also got the same coaching on positioning and latch, which is a reminder that technique is the main fix; a cream is comfort, not treatment. If nipple pain is severe or not improving after a week or two, talk to a lactation consultant, your doctor or a pharmacist.

Should you use it?

If you have dry, cracked skin and no history of reacting to it, lanolin is one of the most effective protectants you can buy, and most people use it for years without a problem. Choose a highly purified grade for lips, nipples or a baby’s skin.

If you have leg ulcers, stasis eczema or long-standing atopic dermatitis, you’re in the group where lanolin allergy is most likely, and there are good alternatives for the same job, petrolatum among them. If a rash appears where you’ve been applying a lanolin product and doesn’t settle within two weeks of stopping it, see your doctor or pharmacist and ask about patch testing.

Lanolin isn’t dangerous, and “lanolin-free” isn’t automatically gentler. It’s a superb old moisturizer that a small, identifiable group of people can’t tolerate. Knowing whether you’re in that group is the whole game.