All About Kojic Acid, a.k.a. the Skin-Brightening Ingredient Derms Love

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By Lindy Segal
Published on November 12, 2024
Small bottle and dropper with clear liquid on pink background
Small bottle and dropper with clear liquid on pink background

It’s official: Acids have taken over our skincare routines. We turn to them for everything from hydration (hello, hyaluronic acid) to exfoliation (thanks, glycolic acid) to getting rid of blemishes (we see you, salicylic acid), and then some. But it’s come to our attention that even some of the most skincare-obsessed among us have been sleeping on one of the most effective acids out there—which is why we’re shining a spotlight on kojic acid, your new go-to for glowy, even-toned skin.

So why exactly is this under-the-radar ingredient worth your precious vanity space (and money)? We caught up with dermatologist Dendy Engelman, MD, to break down how and why it works. Read on to find out all there is to know about kojic acid—before you try it.

Meet the Expert

Dendy Engelman, MD, is a New York City-based dermatologist and Mohs surgeon.

What is kojic acid?

It may not be the sexiest-sounding thing in the world, but kojic acid is a byproduct derived from fermented rice, certain varieties of fungi, and even soy sauce. In skincare, kojic acid inhibits the formation of an amino acid that helps produce melanin, AKA the pigment in our skin. “Kojic acid is a skin-lightening ingredient,” explains Dr. Engelman. In the U.S., you’ll see it in over-the-counter concentrations of around 1%, sometimes paired with other brightening ingredients like vitamin C or niacinamide. It’s worth noting that although kojic acid does act as a skin-lightening agent, its milder results are intended for targeted concerns such as scars and hyperpigmentation—as opposed to controversial skin-whitening creams, which have been traditionally used to chemically lighten, or even bleach, the complexion.

What are the benefits of kojic acid for your skin?

Essentially, kojic acid is your new go-to for even-toned skin. “It is used to brighten dark marks and/or hyperpigmentation from acne scars,” explains Dr. Engelman. When it comes to scarring, you will want to begin treatment as soon as possible, as the derm adds, “It is most effective to treat when the scar is fresh.” Similarly, kojic acid can also have a lightening effect on discoloration due to age spots, sun spots, and melasma.

In addition to helping lighten pesky scars, kojic acid also has antibacterial properties that may help treat acne itself; and on the anti-aging front, it even has some antioxidant protection to help fight free radical damage. But what makes kojic acid such a favorite among dermatologists is its tolerability: Those who have had dryness or irritation from hydroquinone—another skin-lightening agent often prescribed by dermatologists—may have an easier experience using products with kojic acid.

How to use kojic acid in your skincare routine

This ingredient is ultra versatile and can be found in everything from spot treatments to face creams and peel pads to serums, according to Dr. Engelman. Kojic acid can also be used daily, although those with sensitive skin may want to start with twice a week and build up frequency as the skin gets more tolerant. Products with kojic acid can also be used in both your nighttime and morning routines—just remember to follow with sunscreen if you use it in the morning!

One product we love is URBAN SKIN RX’s Super C Brightening Serum, which blends a mega dose of vitamin C, ferulic acid, and kojic acid to help fade dark spots and even skin tone. Hyaluronic acid and peptides also plump up fine lines, making this serum a one-two punch for all things anti-aging and brightening.

Are there any side effects?

Kojic acid is relatively gentle on skin (which is why it’s such a good alternative to hydroquinone), but there are still certain factors you’ll want to keep in mind when using it. “Overall it is very well tolerated,” explains Dr. Engelman, who adds that it is safe to use on sensitive skin. However, if you do develop a reaction such as contact dermatitis, itching, or redness, discontinue use immediately and reach out to your dermatologist.

Kojic acid may also make all skin—yes, including deeper skin tones—more sensitive to sunburn. “It is extremely important to use sunscreen when your skin is healing from a wound, such as acne, and even more so when you’re using a dark spot treatment,” advises Dr. Engelman, who prefers formulas “with at least an SPF 30” for maximum protection.

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