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.

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