Few people would say that they don’t care about their skin. Even if they’re not following a complex multi-step routine that would make K-beauty fans proud, most people do want clear skin that doesn’t look dry, dull, or splotchy. While some people are blessed with good genes and can simply wash their face with regular soap and keep it moving, others might need to finesse their skincare routine to get the desired results.

Specifically, people who struggle with hyperpigmentation often find themselves chasing a miracle product that will fade dark spots and uncover a more even skin tone. One particular product that’s often promoted among natural skincare circles as the solution to the problem is kojic acid soap. So, what exactly is this product? Is it effective at banishing dark marks, and how should people use it to get the best results?

What is Kojic Acid Soap

Sometimes simply referred to as kojic soap, this is a topical cleansing product usually sold in bar soap form that’s applied to a person’s skin. One of the main ingredients in the soap is kojic acid, which is a known topical treatment for hyperpigmentation that’s often prescribed or sold in other formats like creams, ointments, or serums. Unlike prescriptions, kojic acid soap is readily available online and in stores, meaning that people don’t have to visit a dermatologist to purchase it.

Shawnda Dorantes APRN, MSN, FNP-C and founder of Beauty Lounge Medical Spa provides historical context by sharing that “Kojic acid has a rich history, dating back to late 20th-century Japan. A scientist studying the byproducts of sake fermentation (Japanese rice wine) noticed that the koji mold used in sake production had a skin-lightening effect on the workers’ hands. It was discovered that kojic acid inhibits the production of melanin.”

How Does Kojic Acid Work?

What makes kojic acid so effective is that it’s derived from fungi or fermented rice wine. When applied to the skin, it prevents the body from producing tyrosinase, an enzyme that creates melanin. Because of this, it’s often promoted as a solution for treating hyperpigmentation.

Although it’s sometimes been associated with skin bleaching, kojic acid soap will not bleach the skin. For this reason, it can be a popular option for melanated beauties that want to correct hyperpigmentation. As a soap, it’s used just like regular body soap, applied when wet, and then washed off.

Benefits of Kojic Acid

Most research on kojic acid benefits aren’t on its use as a soap, but rather as a topical cream, ointment, or serum. However, most experts agree that people can reasonably assume that similar — if muted — results can be achieved through a soap. Dorantes adds that “Kojic acid can offer great benefits to those dealing with acne scars, hyperpigmentation, and freckles and to those looking to stay young.”

Along with inhibiting the production of tyrosinase, kojic acid is also an antioxidant that can fight free radicals caused by sun exposure. This means that if sunlight is the culprit behind dark spots, kojic acid can potentially help to lessen those effects. Some research suggests that even using a product with just 1% kojic acid is effective enough to counteract melasma in 58% of respondents. But for maximum effectiveness, the topical is usually used in combination with other proven skin-brightening treatments like glycolic acid or hydroquinone. However, it’s not without drawbacks.

Known Risks of Kojic Acid

As with any product, there are always risks, and kojic acid — including the soap form — is no exception. For most people, kojic acid will be a fairly low-risk topical product to use. But similar to other brightening ingredients like retinoids, niacinamide, and even vitamin C, kojic acid is known to increase people’s risk of sun sensitivity, skin irritation, or even cause allergies like contact dermatitis.

So, before hopping in a shower and scrubbing away with a bar of kojic acid soap, Dorantes encourages beauties to always perform a patch test and wait at least 24 hours before applying liberally. Similarly, invest in a good daily SPF lotion or moisturizer to protect the skin from sun damage. And, avoid using this product when there are open cuts on the skin.

How to Use Kojic Acid Soap

Depending on who’s consulted, some people will encourage daily use while others will recommend limiting use to a few times per week. The best frequency will depend on a person’s existing skin sensitivities and how their skin responds to treatments. Understand that results can take a few months to show, so be dedicated to the cause before incorporating kojic acid soap into a weekly skincare routine.

Whether for the face or body, many experts recommend starting with nighttime treatments to minimize the risk of skin sensitivity. Likewise, if using the soap for targeted areas, treat it like a spot treatment rather than applying liberally all over.

Additionally, those with sensitive skin may find that they need to take breaks during treatment. It’s not uncommon for people to begin a regimen for a month or two and then take a break to give their skin time to recover.

The following simple tips are ideal for using kojic soap as a cleanser:

  1. Make sure the skin is wet before application
  2. Create a lather with the soap and then apply to skin
  3. Let the kojic acid soap sit on the skin for 1 to 2 minutes
  4. Rinse the soap off and pat skin dry
  5. Follow up with a moisturizer and apply sunscreen that’s at least SPF 30 when out during the day

If using kojic soap as a spot treatment, follow the same steps as above, except only apply the soap to areas with hyperpigmentation.

Is Kojic Acid Soap Right for You?

Skincare is personal so what works for one individual may not be right for another. However, kojic acid has a proven history of effectively reducing dark spots and treating hyperpigmentation. Even though most studies focused on more concentrated treatments like serums, ointments and creams, anecdotal evidence suggests that kojic acid soap could yield similar results — even if the timeline for achieving them is longer. Ultimately, people will need to weigh the benefits and risks of using kojic acid soap and choose accordingly.