With winter preparing to make a gusty entrance — and fingers hovering above the indoor heating "on" button — it makes sense to start thinking about doubling down on hydration. When it comes to cleansers, creams, lotions and lip balms, we've got a lot of ingredients to choose from, not limited to nut butters, fruit oils, hyaluronic acid and ceramides. Today we're focusing on lanolin, specifically, a moisturizing ingredient that tends to get overlooked and misunderstood.

Image via @lanolips

In short, lanolin is a wax that's secreted by the sebaceous glands of wool-bearing animals — most notably, sheep. It's sometimes referred to "wool grease" or "wool wax" and it's responsible for keeping the animal's skin and fur protected from the elements.

"Lanolin has long been used in skin care because it is an effective emollient. It's commonly used in body creams and lotions to lock in much-needed moisture and prevent water loss," explains Dr. Hadley King, a board-certified dermatologist based in New York City. "Because of its high fat content, lanolin is occlusive, meaning it prevents the evaporation of water from the skin. This keeps skin moisturized and helps it heal."

Image via @lanolips

Anyone who's susceptible to dry skin (including the face, hands and lips) can benefit from lanolin's moisturizing properties. And let's face it — that's #allofus come winter. That said, King notes that it's "particularly great for eczema-prone skin types" and notes that it's even used to help expedite the healing process for minor scrapes, cuts, burns and irritation.

There are a handful of products out there, each formulated for specific purposes, that you can try. For example, the brand Lano makes lanolin the hero ingredient in all its products. Some favorites include Coconutter Hand Cream Intense ($15), which is made with pure lanolin, coconut oil, coconut milk and vitamin E, and 101 Ointment Multipurpose Superbalm ($17).

Additional examples include Go-To Lips ($12), Aquaphor Healing Ointment ($14) and Glossier Balm Dotcom ($12).

It's true that some people are allergic to lanolin, but only a small percentage of the population is affected. Dr. King says that recent studies, including this one from 2013, have estimated that approximately 2 to 3 percent of the population may experience a lanolin allergy.

Bella Schneider, a celebrity esthetician and the CEO of LaBelle Day Spas & Salons, notes an additional study published in 2008 that found Lanolin as the ninth most common allergen found in moisturizers. Ingredients that people are more commonly allergic to include fragrance, parabens, vitamin E, essential oils, benzyl alcohol and propylene.

To be safe, Schneider and King both recommended patch-testing a small area before lathering on any potentially irritating product.

"If you have an allergic reaction to lanolin, you will mostly likely experience an itchy skin rash on the area of the body where the product containing lanolin was applied. It may take a few hours or up to a day or two for the skin to react," says King. "A lanolin skin reaction most commonly takes the form of a mild allergic contact dermatitis, which will show up as a scaly patch of skin or small, red itchy bumps."

In the case of a severe allergy, it's possible to have swelling, blisters and itching or burning. If you are allergic to lanolin, don't fret. There are many other ingredients that also prevent "transepidermal water loss" (aka evaporation of moisture from your skin). These include beeswax, coconut oil, shea butter, cocoa butter and mineral oil.

Image via Imaxtree