Lanolin is a yellow, sticky substance that's derived most commonly from the sebaceous glands of sheep, although it can come from other wool-bearing animals like goats as well. It can't be made synthetically. In sheep, this oily substance helps to protect their coats against the environment and insect bites. Lanolin can be obtained from sheep without harming them. When sheep are sheared to remove their coat, the lanolin can be extracted by squeezing the wool between tight rollers without harm to the animal. Lanolin has been used topically for thousands of years to treat dry skin and other skin conditions.
Lanolin has a variety of commercial applications. It's used for industrial purposes and has medical and cosmetic applications. Industrially, lanolin is used to make lubricants for metal parts and musical instruments and to make water and dirt repellant coatings. It's used to protect metal parts including cars and boats against rust and corrosion. It's also an ingredient in shoe polish and products used to condition and protect leather. In the medical and pharmaceutical industry, lanolin is an ingredient in some ophthalmic products and is used in the production of vitamin D for supplements and to soften chewing gum. Some doctors recommend medical-grade lanolin to treat nipple soreness in women who are breastfeeding.
In the cosmetic and personal care industry, lanolin is an ingredient in a wide array of products including moisturizers, baby products, soaps, personal lubricants, shaving creams, hair products and sun protective products. In these products, it functions as an emollient to soften and smooth skin and as a skin and hair conditioning agent. It also helps to stabilize emulsions. Cosmetics are typically formulated with both oil and water-soluble ingredients. Emulsion stabilizers like lanolin help to keep the two phases from separating. This allows the product to function better and extends its shelf-life. For hair, lanolin has anti-static and conditioning properties.
As a moisturizer, lanolin is an occlusive and an emollient. As an emollient, it coats the outer layer of the epidermis and prevents water loss. Lanolin is very effective for preventing loss of water through the skin. It contains cholesterol, a fat naturally found in the outer layer of the skin that reduces water loss and keeps skin moist. Some studies show that lanolin is a better moisturizer than petrolatum, considered to be one of the best ingredients for reducing moisture loss. Petrolatum is derived from crude oil, while lanolin comes from natural sources.
Although lanolin is an effective skin occlusive and emollient, it has a reputation for being an allergen. Although some people are allergic to lanolin, the problem may not be as widespread as previously thought. A study published in the British Journal of Dermatology found that 1.7% of people are allergic to lanolin. Despite the relatively low rate of contact allergy to lanolin, some cosmetic companies have removed lanolin from their products and advertise them as being lanolin-free. Lanolin is made up of fatty alcohols, fatty acids, cholesterol and wool alcohols. Most people who are allergic to lanolin are reacting to the wool alcohols in lanolin. Therefore, people who are allergic to wool should avoid using products that contain lanolin. People who are allergic to the wool alcohols in lanolin typically experience an itchy rash, skin redness and swelling after using a product containing lanolin. Patch testing is used to determine whether a true lanolin allergy exists, although patch testing may not be 100% accurate. Patch testing uses wool alcohol as the challenge, and it's not clear whether other components in lanolin also cause allergic reactions and contact dermatitis.
All in all, lanolin is a very effective moisturizing agent that helps skin hold on to moisture. It's still one of the most effective treatments for dry, itchy skin. There's still the perception that allergies to lanolin are common, but these days lanolin is more purified, which may account for the relatively low incidence of allergies seen in more recent studies. If you're not allergic to wool and haven't had a problem with lanolin in the past, there's no reason to avoid it.