What the heck is kojic acid soap?

what is a kojic acid soap?

Ever heard of kojic acid soap?

When I first heard of it, I was like….”kojic whaaaat?”

What the heck is that?

Then I did some digging. That digging led me into buying.

After buying and using the product for about 3 weeks, I was HOOKED.

It got rid of my acne scars and evened my skin tone!

I was like…..OMG! This is working!

So, without further ado….

What is kojic acid soap?

In simple terms, it’s a soap with kojic acid in it that can help get rid of dark spots and hyperpigmentation.

Kojic acid is an all-natural byproduct of fermented (acidified) rice wine.

At first, Japanese women started using kojic acid as a food preservative. But then, they realized “OMG, our skin is getting lighter!”

This is when kojic acid was discovered as a skin lightening ingredient.


  • Natural ingredient – a byproduct of fermented wine.
  • Discovered in Japan in 1907.
  • Widely used as a preservative in many Japanese foods like miso, soy sauce, sake and rice wine.
  • From several types of fungi (the good ones though).
  • Has been in the market since 1955 when Pfizer started developing organic acids.
  • Has the ability to stop melanin from producing, which helps lighten the skin.
  • Can get rid of dark spots and hyperpigmentation by stopping  the production of melanin.

How it works:

So how does it work? Well, kojic acid works by stopping melanin production.

Melanin is the pigment responsible for producing your skin color. It’s also found in your hair, eyes, etc.

When your skin stops the producing melanin, the result is a lighter and even skin tone.

This is why most people refer to kojic soap as “skin lightening soap.”

3 types of kojic acid soap:

1. Natural

What is a natural kojic acid soap? It’s basically soap base + kojic acid + naturally-derived ingredients.

No additional chemicals or synthetic ingredients.

How to identify:

  • Cold-processed. Meaning you’ll see these ingredients: coconut oil, sodium hydroxide + water (also called saponified coconut oil).
  • Contains shea, cocoa and other plant-based butters.
  • Doesn’t have fragrance.
  • Contains colorant (this is typical with kojic to distinguish it from other soaps). Note that the usage of colorants  are very minimal that’s why you see it at the very the end of the ingredients list.
  • Minimal ingredients.

2. Conventional (Cold-processed)

This is very common type of kojic soap because it’s made in bigger batches. They’re also cold-processed but they contain additives like preservatives to prolong shelf life.

How to identify:

  • Conventional soaps are also cold-processed (coconut oil, sodium hydroxide + water (also called saponified coconut oil).
  • Has fragrance.
  • Contains colorant.
  • Contains preservatives
  • Includes emulsifying agents

3. Melt and Pour

Melt and pour kojic soaps are basically made with pre-made soap base + kojic acid. This type is usually cheaper because the base is already made and the only thing that needs to be done is to add kojic acid in it.

This means less work for whoever is making it.

In my opinion, this type of soap isn’t as effective as cold pressed.


It’s because kojic acid is soluble in water. In order for it to work, it must be dissolved in the water phase of soap making.

If you add kojic acid in an existing pre-made soap base, kojic acid would more than likely not dissolve properly. If it doesn’t dissolve properly, then how can it be effective?

How to know if you’re buying a melt and pour soap:

  • Look at the ingredients: if it contains ingredients like sodium myristate, sodium stearate, sodium laurate, propylene glycol, then more than likely, it’s a melt-and-pour soap.


Price ranges from $7 to $30 USD.


Here are the common ingredients found in kojic acid soaps.

NOTE: Not all kojic soap brands have these ingredients. Some are natural-based and the others aren’t. Use this as a guide to learn what’s on the soap that you’ll be buying but ALWAYS check the ingredients first.

  • Aqua + Sodium hydroxide + Oil (mostly coconut) – this is the soap base.
  • Carica papaya extract – Papaya extract an enzyme that exfoliates the skin to get rid of dead skin cells. Another benefit is it helps make the skin look even-toned.
  • Kojic acid – primary ingredient.
  • Vitamin E – reduces oxidation.
  • Vitamin C – natural preservative.
  • Fragrance (mostly citrus) – makes the soap smell great. Although this doesn’t add any potency to the product.
  • Colorant (mostly color Orange) – used to distinguish it from other soaps like glutathione, glycolic, etc.
  • Shea butter / Cocoa butter – used as moisturizers
  • Mineral oil – moisturizer. However, this can clog pores.
  • Glycerin – helps glide easily.
  • Cocamide DEA (cocamide diethanolamine) – emulsifying ingredient. CAUTION: This ingredient is recognized by the California Office of the Environmental Health Hazard Department as a potential cancer-causing ingredient.

Therefore, Cocamide DEA is under the Proposition 65 list. For more information, you can read this article. On the other hand, the FDA is saying that it’s a safe ingredient to add in personal care products. It’s up to you on who to believe.

4 Benefits of using kojic acid soap:

  1. Removes dark spots/hyperpigmentation.
  2. Evens skin tone.
  3. Exfoliates and smoothens the skin.
  4. Lightens skin tone.

If you use the soap consistently, it can help get rid of these problems:


  • Acne hyperpigmentation/pimple marks
  • Age spots
  • Freckles
  • Melasma
  • Sun damage (like sun spots)


  • Inner thigh discoloration
  • Dark underarms
  • Back acne scars (Bacne)
  • Butt acne scars (Buttne)
  • Knees
  • Knuckles
  • Elbows
  • Neck

5 Possible Side effects:

Note that not everyone would experience these side effects.

1. Burning sensation

If you’ve never used kojic acid soap before, then you’ll more than likely going to experience a burning sensation during the first couple of times that you’ll be it. However, this can also happen when you leave the soap on your skin longer than the suggested time or if you have sensitive skin.

Note that I DO NOT recommend using kojic acid on sensitive skin as it’s too strong.

For those of you who will be using the soap, I strongly recommend to follow these tips:

  1. Follow Rosey’s 30-second rule: do not leave it on your skin for more than 30 seconds (facial area).
  2. Only use it 2-3 per week until your skin starts to get used to kojic acid.

2. Dryness

Your skin will be dry for sure. It could also get flaky but don’t worry, this is normal.

One of the things I want to add is that kojic acid microexfoliates the skin, so drying and flakiness isn’t a cause for concern.

The best thing to do is to use 100% natural oils to bring moisture back to your skin.

3. Heightened skin sensitivity

Kojic acid has a sun sensitizing effect to the skin. So, it’s important that you don’t stay under the sun if you plan on using kojic acid soap for the long term.

4. Skin Erythema

Mild facial erythema has also been reported as a side effect to using kojic acid soap on sensitive skin. Symptoms include redness and rashes on the cheeks and forehead.

If redness or bumps start appearing, calm the affected area with cool water and apply anti-inflammatory ingredients like Aloe Vera to temporarily soothe affected areas.

Stop using the soap if you experience this.

5. Contact dermatitis

Another possible side effect is allergic contact dermatitis – making skin irritated, inflamed and sometimes, causing rashes.

In the event of contact dermatitis, treat with a soothing gel to calm the affected area. You may also use antihistamine if affected areas start to itch.

If symptoms of any side effect mentioned persists, discontinue use of kojic acid soap and consult your dermatologist.

How to use the kojic acid soap:

This is one great question!

How do you use the soap for maximum results? It’s easy and very simple.

The instructions below assumes that you don’t have makeup on. If you do, completely remove your makeup first before following the steps.


  1. Wet your face with warm water.
  2. Lather and apply the soap on your face (use a rotating face brush, konjac sponge or a microxfoliating face towel for better results).
  3. Rinse thoroughly with cold water
  4. Apply a natural face oil (I recommend Tamanu Oil. DO NOT use any products that contain acids like glycolic, lactic, etc.)

4 top questions about kojic acid soap:

1. Is kojic acid bad for your skin?

The answer is no. Kojic acid is actually good for the skin because it helps get rid of dark spots/hyperpigmentation. However, it becomes “bad” when you overuse it.

I’ve seen people talk about how long they leave kojic acid soap on their skin and honestly, I’m just shocked.

Avoid overusing the soap by leaving it on your face for less than 30 seconds and then about 5 minutes on the body.

2. Can kojic acid permanently lighten skin?

No and there’s no such thing. No kojic soap brand or any kind of skin lightening product can lighten your skin permanently.

Remember than kojic acid works by stopping melanin from forming. Once you stop using kojic acid on your skin, then your original skin color will come back.

3. What happens if I stop using Kojic Acid Soap?

Just like what I stated above, your skin tone will go back to its natural color. One thing that you can do to avoid this from happening is to use the soap for maintenance.

This means that instead of using the soap for about twice a day, you’ll only be using it for about twice a week.

4. How long should I leave kojic acid soap on skin?

In order to see its maximum effect, you should leave the soap for about 15 to 30 seconds on your face (10 seconds if you’re just starting out) and rinse with cold water. Then leave it about 5 minutes in the body area.

I use the soap in my underarms and I just want to warn you that it may cause some stinging when you apply deodorant.

4 tips to make kojic acid soap work for you:

1. Use a very strong kojic acid soap.

There are plently of kojic sops out there. Some are cheap, some are expensive. But if you really want to get rid of your dark spots, then I suggest that you invest in a good kojic soap that’s proven to get rid of hyperpigmentation.

After all, it’s still cheaper compared to a derma visit.

2. Use a konjac sponge or a micro-exfoliating face towel.

If you actually use a konjac sponge or a face towel while using the soap, you’re increasing its power by 100%.


It’s because these two helps exfoliate dead skin cells, which would allow kojic acid to penetrate your skin deeper and faster.

3. Do not overdo it.

What do I mean by this?

DO NOT use any kind of acids (glycolic, salicylic, mandelic, malic, etc.) while using the soap. It’s TOO MUCH!

Do not stress your skin by applying all these unnecessary products.

What I suggest is to use a mild facial cleanser (to remove makeup), then kojic acid soap and lastly, a natural face oil (Tamanu Oil, Sesame, Rosehip, Jojoba, etc.). This should be your routine. Very simple but it works.

4. Be patient

It does work. There’s no doubt about that. But you can’t expect for it to work overnight.

It usually takes between 4-8 weeks to see results. Be patient.

Top 3 before and after pictures:

This article won’t be complete until you see proof that kojic acid soap really works.

Here’s my favorite top 3 before and after pics:

1. Kojic acid soap got rid acne dark spots.

Problem: Acne dark spots (aka hyperpigmentation)

Product used: Pure Kojic Acid Soap (Maximum Strength) For Dark Spots & Hyperpigmentation, Evens Skin Tone

Usage time: April to July (3 months)

Skin tone: Medium to dark

Brand: Marie France



2. Kojic acid soap got rid of acne and acne marks.

Problem: Acne and acne marks.

Product used: Kojie San Orange Whitening Soap, 3 x 65 g

Usage time: Over a month.

Skin tone: Fair

Brand: Kojie San

3. Kojic acid soap lightened dark underarms.

Problem: Dark underarms

Product used: Koji White Kojic Acid & Papaya Skin Brightening Soap

Usage time: Unknown

Skin tone: Fair to Medium

Brand: Koji White


Not only can kojic acid soap improve skin conditions for the face, but also for the body. It helps exfoliate, balance out skin tone, reduce hyperpigmentation, and lighten skin tone. Kojic acid is frequently chosen by people to treat freckles, melasma, and sun damage. Using kojic acid soap correctly will readily improve the condition of body skin. Dark underarms and inner thigh discoloration are improved, acne on the neck, back, knees, elbows, and knuckles.

There you have it ladies and gentlemen. I think this sums up everything you need to know about kojic acid soap.

Should you have any questions, let me know by commenting below or by sending me an email.



Photo credits: Amazon

By Rosey

Kojic Soap Queen. Vegan. Dog mom.

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