Kojic Acid Is the Dermatologist-Loved Ingredient for Preventing Dark Spots

You likely already know about (and probably use) glycolic and salicylic acids in your beauty routine, but there's another somewhat under-the-radar acid that deserves some time in the skincare spotlight—particularly if your goal is a brighter, more even complexion. We're talking about kojic acid, a naturally-derived ingredient. It comes from mushrooms (more on that in a minute) and is excellent at fading hyperpigmentation and discoloration aka dark spots. It works well both on its own and when paired with other lightening ingredients, not to mention also acts as an antioxidant. Ahead, experts explain why and how kojic acid works, who should give it a whirl, and which products to try.

What is Kojic Acid?

As we mentioned, mushrooms are the source of kojic acid, a byproduct of various fungi that also occurs as the result of the fermentation of certain Asian foods, such as soy sauce and rice wine, explains Chang. "Unlike other acids that work by dissolving the bonds between the cells and exfoliating the skin, kojic acid works by inhibiting pigment production," she says. It also has the added benefit of working well when paired with other skin-lightening ingredients (namely the gold standard hydroquinone, most commonly prescribed by derms). Dermatologists often combine it with hydroquinone for a synergistic, prescription-strength lightening agent, notes Bhanusali. But on the flip side, it works well on its own, too, and is a great alternative for those who can't tolerate or don't want to use the more potent hydroquinone. "It’s also less likely to cause an overly-white appearance of the skin, making it a good option for people with darker complexions who'd be more likely to [experience extreme lightening] from using other ingredients," says Nazarian.

Benefits of Kojic Acid for Skin

Spot-fading and skin brightening is the name of the game for this ingredient, though it does have a few other standout qualities.

• Inhibits the production of melanin in the skin: The pathway that leads to excess melanin or pigment (in other words, a dark spot) is complex, but at the heart of the matter is an enzyme known as tyrosinase. Kojic acid blocks UV-activation of tyrosinase, thereby limiting the production of melanin. This means it can help lighten existing sunspots and photodamage, fade the dark marks left from acne scarring or after a pimple, and even improve melasma, notes Chang.
• Acts as an antioxidant: Kojic acid can help scavenge and counteract skin-damaging free radicals caused by exposure to things such as UV damage and pollution. This not only helps improve overall skin tone as well but also makes it a good general anti-aging ingredient, says Nazarian.
• Has anti-inflammatory and anti-viral properties: Unlike many other acids, it also has these unique characteristics, though they're secondary to the skin-lightening benefits.

Who Should Use Kojic Acid

Anyone seeking to improve the look of discoloration caused by sun damage, melasma, and/or post-inflammatory hyperpigmentation that occurs after a blemish, says Chang. Bhanusali adds that it's also a good option for those who want to avoid or can't tolerate hydroquinone, one of the most often used skin-lightening ingredients.

Side Effects of Kojic Acid

"Generally speaking, kojic acid is better tolerated than most acids, but an allergy or irritation is certainly possible," points out Bhanusali. A red rash, itching, irritation, and burning are the most common side effects, adds Chang, though these are typically uncommon if you're using lower concentrations of the ingredient (and most over-the-counter products do contain a lower concentration).

How to Use It

If your skin is super sensitive, Nazarian recommends not using it daily at first; instead, work kojic acid-based products into your regimen just once or twice per week to ensure that your skin can tolerate the ingredient. Also worth noting: "When used over time, kojic acid may also make your skin more susceptible to the sun," says Chang. Using sunscreen daily is always important, but even more so when kojic acid is in your skincare mix.