What Is Urea in Skin Care? A Dermatologist Explains

Anyone who's ever attempted to read the ingredients list on the packaging of skin-care products knows just how confusing the task can be. There are some ingredients that are more commonplace and therefore easier to recognize — like hyaluronic acid, salicylic acid, and ceramides — but then there are ingredients like urea that can leave you scratching your head and wondering: what is urea?

If you're stumped by this ingredient, allow us to shed some light on what urea is, its skin-care benefits, and how to use it in your routine. Ahead, a dermatologist answers all of your questions.

To start, let's establish what urea is in the context of beauty. "Your skin has a natural moisturizing factor (NMF), which helps the skin hold on to water and stay plump and hydrated," Shereene Idriss, MD, a board-certified dermatologist and the founder of Idriss Dermatology in New York City, tells POPSUGAR. "Urea makes up seven percent of your NMF." The rest of your natural moisturizing factor is made up of amino acids, lactic acid, and pyrrolidone carboxylic acid.

The skin isn't the only place to find it. "[It] can be found naturally in pee," Dr. Idriss says. But have no fear, that's not the same type of urea that's in your beauty products. "In commercial cosmetics, urea is made synthetically in the lab and is commonly added back even into baked goods and wine that we consume happily."

Every ingredient has a purpose and reason for being included in a product. Urea has two main benefits. "[It] acts as an agent that helps to break up dead skin cells," Dr. Idriss says. "It also has moisturizing action." Meaning you'll find urea in both hydrating and exfoliating products.

Urea is a humectant, just like hyaluronic acid, and attracts moisture from the environment (like the air) and the skin itself to hydrate. It's also a keratolytic agent, which is how it gets its exfoliating properties. It works by breaking down protein keratin in the skin, effectively getting rid of flakes and dry patches.

Dr. Idriss recommends that if you're hoping to reap the benefit of exfoliation from urea, you should look for products with a urea concentration greater than 10 percent.

You'll find urea in skin-care products starting at a concentration of just two percent and ranging up to 40 percent. "If it's less than 10 percent, it's primarily used as a moisturizer," Dr. Idriss says. "If it's above 10 percent and up to 20 percent, it can be used to treat skin conditions like rough skin patches, calluses, cracked heels, and keratosis pilaris." This makes it great to use on the body where skin is thicker and can tolerate heavier exfoliation, like on hands and feet.

The list of potential side effects of urea is short. "As with anything, it may cause some very mild skin irritation," Dr. Idriss says. "If you develop any symptoms like stinging, itching, [and] burning, you may have an allergic reaction."

On the bright side, urea can also help increase the absorption of other skin-care ingredients in your routine. This can make them even more effective, but it can also make them more irritating.

Some ingredients play nice together, while others don't. In general, urea is pretty easy to incorporate into your routine — you'll just want to use caution when combining it with other exfoliating ingredients, like salicylic acid, glycolic acid, lactic acid, and retinoids, as it might "render it more potent" and lead to irritation, according to Dr. Idriss. It's best to stick to one exfoliant at a time.