Kojic Acid is one of those holy grail ingredients of skincare when it comes to hyperpigmentation and dark spots. It can be obtained in various forms like creams, lotions, serums, powders, and soaps.
This article will focus specifically on Kojic Acid Soap – everything we need to know- benefits, side effects, results, use, and which brands work the best.
What is Kojic Acid
Kojic acid is a compound that is made from fermenting certain Asian foods like soy, rice wine, Japanese sake, and others.
In skincare, it is used to treat hyperpigmentation (darkness of the skin which occurs when too much melanin is produced and deposited in the skin).
Kojic acid works by inhibiting the production of tyrosine which is an amino acid that is vital in the production of melanin (pigment) in the skin. It does this by blocking the UV activation of tyrosinase, the enzyme that helps to make tyrosine.
Benefits Of Kojic Acid Soap For The Skin
When used consistently, Kojic acid soap:
1- Lightens the skin
Kojic acid soap will lighten patches of hyperpigmentation, dark spots, sun spots, and melasma. Its ability to disrupt the melanin production pathway itself makes it an effective treatment for the darkness of the skin.
Related article: Kojic Acid for Dark Underarms- How to Use Correctly & Risks
2- Protects the skin and reduces signs of aging
Kojic acid also acts as an antioxidant. It fights free radicals in the skin which damage skin cells and cause wrinkles and fine lines to develop more quickly. Over time, it helps to keep the skin cells healthier for longer.
Related Article: How to Use Kojic Acid for Under-Eye Circles & Wrinkles
3- Has antimicrobial properties
kojic acid has been found to have some antibacterial and antifungal properties. It may help to fight off some common kinds of bacteria that cause acne (so it can help to manage mild to moderate acne) and it is useful in treating some mild to moderate fungal infections of the skin.
4- Gently cleanses the skin
Kojic acid will not deeply exfoliate your skin like other kinds of “acids”. However, in the soap form, it will gently lift away dead skin cells, dirt, and oil from the skin. It will also tighten your pores over time.
Some other great types of soaps to consider are:
Side Effects Of Using Kojic Acid Soaps
The most common side effects associated with using Kojic acid soap are irritation, dryness, and contact dermatitis.
These side effects are less when a low concentration of Kojic acid is used.
Contact dermatitis can present with redness, irritation, itchiness, rashes, swollen skin, or pain and discomfort. This usually happens when kojic acid is used in concentrations of more than 1% (I do not recommend doing this).
I recommend that you moisturize well when using Kojic acid soap. I have normal skin (not too oily and not too dry) and when I used Kojic acid soap I needed the extra moisture. While it didn’t leave my skin crusty, it felt a little dehydrated after a few days.
If you have dry and sensitive skin, your moisturizer will help to prevent irritation so that you can get the most benefit out of your kojic acid soap!
Some other great soaps to use are:
How To Use Kojic Acid Soaps
Kojic acid soap can be used like regular soap (externally, all over your body, except on the sensitive skin of your private areas).
I do not recommend using a high concentration of kojic acid. Look for a soap that contains 1-2% of kojic acid to prevent side effects.
Kojic acid soaps are generally very sudsy (they create lots of foam and lather well) so a little will go a long way. Here is what to do:
- Wet the skin
- Lather up the soap in your hand or directly on your body
- Spread it all over the body with gentle massages
- You may use a soft loofah to gently physically exfoliate the skin (but do not scrub at your skin – this can irritate it)
- Let the soap sit on your skin for 1-2 minutes and then wash it off well
- Pat your skin dry and then apply your daily moisturizer all over
- If you are going out, use a moisturizer with SPF or apply your SPF separately. Kojic acid can make your skin more susceptible to sunburn.
How Often Can You Use
You can use your kojic acid soap every day or as often as your skin can tolerate it without side effects. If you notice your skin becoming dry or irritated reduce how frequently you use the soap.
Video: Kojic Acid for Dark Spots and Melasma
The Safety Of Using Kojic Acid Soaps
Kojic acid is not regulated by the FDA. However, the Cosmetic Ingredient Review Expert Panel has approved the use of kojic acid in cosmetics in concentrations up to 1-2%.
Various studies on the general safety of kojic acid have been conducted by different research bodies indicating that when used in concentrations of 1-2%, Kojic acid is non-toxic as it is slowly absorbed into the skin.
Please note that there are currently no skin-lightening ingredients (including kojic acid) that are approved for use by the FDA. They also specifically monitor products made with skin-lightening agents like Kojic acid for safety concerns and they have a voluntary registration program through which companies can report how their products are made.
When buying kojic acid products, I usually do a little research to see whether the product has been on the FDA’s radar for any reason and check product reviews for other users’ experience with the product.
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Frequently Asked Questions
Can you use kojic acid soap while pregnant and/or breastfeeding?
There is limited research on the use of kojic acid during pregnancy and breastfeeding. However, it is considered to be generally safe for use once approved by your doctor.
I recommend that you speak to your doctor about your skin concerns and have them decide what concentration of kojic acid would be best for you to use.
Can you use kojic acid soap on your private parts?
I do not recommend using kojic acid soap on your private parts.
Kojic acid can be irritating to the skin, especially sensitive skin. You may use kojic acid soap on your inner thighs and around your private area (keeping to the external skin) but avoid getting it inside any folds or on sensitive areas.
Will Kojic acid soap help to lighten inner thighs?
Yes. Using kojic acid soap on your inner thighs will help to lighten them.
Of course, like so many of us, I have “thick thighs” problems with chaffing and friction, which causes dark inner thighs. I started using kojic acid soap on my inner thighs a few months ago and the difference it has made is amazing. I just need to remember to moisturize the area well every day and I am good to go!
Will Kojic acid soap lighten dark underarms?
Yes. Using kojic acid soap consistently will lighten dark underarms.
Just keep in mind that you will need to moisturize your underarm skin well and avoid things that can irritate the already sensitive skin (frequent shaving or waxing, irritating products, etc).
Click here to read more about using Kojic Acid for Dark Underarms- How to Use Correctly & Risks
How long will Kojic acid soap take to lighten the skin?
If you use your kojic acid soap every day, you should begin to see noticeable differences in your skin within 1-2 weeks.
However, this can vary for every person based on the condition of their skin. Some people (especially those with more severe hyperpigmentation) may take longer to see visible results. It will also depend on the cause of the hyperpigmentation and on daily lifestyle habits that can worsen or help to prevent hyperpigmentation as well.
It took me 7 days to see some results! But once I did, there was no going back.
What happens when you stop using kojic acid soap?
Unfortunately, if your hyperpigmentation is being caused by something chronic (long-term), it will eventually come back when you stop using kojic acid soap or other kojic acid treatments.
Kojic acid will inhibit melanin production in the skin for as long as it is used. But when it is stopped, and after it is no longer in the skin, melanin will resume being produced. It is a temporary solution.
It works great for hyperpigmentation that is caused by short-term causes (scars, acne scars, melasma, sun spots, etc). However, if you have hyperpigmentation from chronic illnesses like diabetes and PCOS (acanthosis nigricans), and they are uncontrolled, then the hyperpigmentation will return.
Best Kojic Acid Soaps To Use
1- Kojie San Skin Lightening Soap
I use this soap for my hyperpigmentation issues and I love it. It is great for sensitive skin but it can be a little drying so always moisturize. I saw results on my inner thighs and underarms within 7 days!
2- Koji White Kojic Acid Skin Brightening Soap
Koji White is another very popular Kojic acid soap and from my research, its popularity comes from how effective it is. It is made of natural ingredients and is cruelty-free, SLS-free, and paraben-free.
3- VALITIC Kojic Acid Dark Spot Remover Soap Bar
This soap bar is another fan favorite on the Kojic acid train. However, it does not only contain kojic acid. It also contains Vitamin C, Retinol, Collagen, Turmeric, Hyaluronic Acid, Vitamin E, Shea Butter, and Castile Olive Oil. It is great for daily use.
However, I recommend that you patch-test your skin first before starting to use this soap. Because of the addition of retinol and vitamin C, the combination with kojic acid may be too much for some skin types. However, if your skin can tolerate it, it works!