How to use AHA/BHA • K-Beauty Ingredient Spotlight

The Korean Beauty for beginners series continues with some informative ingredients posts where we cover the most popular and interesting ingredients which you can find in Korean cosmetics. Let’s start today with AHA & BHA!

Physical VS. Chemical exfoliators

Both AHA & BHA are chemical exfoliants. Chemical exfoliating products differ from physical exfoliators in the way they scrub off dead skin cells. Physical exfoliating products work on scrubbing away the dead skin cells on top of the skin with ingredients like peach stones and strawberry seeds. Because this causes friction between the ingredients and the skin this might be irritating on sensitive skintypes. Chemical exfoliators work from below the surface of the skin and gently attack the dead skin cells with active ingredients.

What is AHA?

Alpha Hydroxy Acid is a water soluble chemical exfoliant which treats dry, dull and patchy skin. AHA dissolves the binding material that holds together dead skin cells making room for new skin cells to reach the surface of the skin. It’s easier for your other skincare products to soak into the skin when your dead skin cells are replaced by fresh new cells. AHA also has humectant properties which simply means it locks in the moisture on your skin.

So what results will I see?

As you probably guessed already new skin cells make your skin appear brighter, less dull and even out the complexion. Clear skin aside, AHA is known to thicken the epidermis (upper skin layer) and increase the collagen production. If you like plump looking skin and want to tackle any (premature) wrinkles you must maintain the collagen balance of your skin.

How can I find an AHA product?

If you read product labels you might not even know there’s AHA inside of your skincare products. This is because there are different types of AHA which all have different benefits. We created a list of the most common ones below:

  • Glycolic Acid: most popular and most common AHA because of it’s small molecular size. This means that it can easily penetrate into your skin and do it’s job. However, it can also mean it can easily irritate your skin if you use to much. Start out with a lower percentage (-10%) of glycolic acid and use every three days.
  • Lactic Acid: second most common AHA. This active ingredient is derived from milk and great for tackling redness. People with Rosecea or sensitive skin in general will benefit the most from this AHA. It’s molecular size is bigger than the size of Glycolic Acid but not as big as with Mandelic Acid.
  • Mandelic Acid: great for acne prone skin because of it’s anti-bacterial and anti-microbial properties. Because it’s molecular size is the biggest of all of these AHA’s it takes longer to get into action but it makes it less irritating.


BHA (short for Beta Hydroxy Acid) is an exfoliant which is known as the ‘pore care’ master. It is most effective for acne prone and oily skintypes since it’s an oil soluble active. It sinks into the pores deeply and de-clutters the pores from any accumulated dirt. The most used and well known BHA is salicylic acid.

Salicylic Acid

Salicylic Acid is derived from salicin which makes it unsuitable for people with aspirin allergy (sorry). This active is known for it’s anti-inflammatory effect which makes it great for calming inflamed skin. Because of this effect salicylic acid is a common ingredient in anti-dandruff shampoos too! Salicylic acid has all the great benefits of AHA like brightening, firming and increasing the collagen production. However Salicilyc Acid doesn’t posses any humectant ingredients like AHA. Because of this it can make the skin dryer which makes it unsuitable for dry skin. However, it’s still way more gentle then other acne treatments like benzoyl peroxide.


How to apply AHA / BHA

With different active ingredients you have to layer them correctly into your skincare routine. Unless you are a skincare pro we recommend staying with one active at a time. This also includes vitamin C and other active ingredients. Because AHA can cause photo sensitivity we recommend to apply AHA only in your nighttime skincare routine. Even though it hasn’t been proven yet if BHA causes photo sensitivity or not, we recommend applying it in your evening routine only just to be sure. When you do want to apply AHA / BHA in your morning routine never skip your sunscreen! But you are wearing sunscreen already every day right?

Correct order to apply: cleanse ❤ toner ❤ AHA / BHA ❤ essence ❤ serum ❤ moisturizer ❤ mask


So in short: choose AHA if you are more of a dry skin type and BHA if you are more of an oily skin type. Have normal or combined skin? Yay, just pick whatever product sounds interesting to you and start gradually adding it into your skincare routine to see how your skin reacts. This should be the procedure for all skintypes though. You don’t need to use AHA or BHA every single day but you can adjust it to your skin’s needs.


If you are interested you can read Sugarmew’s verdict on the popular Cosrx BHA Blackhead Power Liquid here!


Hope this was helpful!

Love, Ichigo

18 thoughts on “How to use AHA/BHA • K-Beauty Ingredient Spotlight

  1. Matilde says:

    Hi! I’ve been using BHA and AHA for a while and neither ever caused me irritation before. But the last couple weeks, both irritated my skin. The only thing that changed in my skincare routine is my cleanser. The one i have now does have some irritants in it. What cleansers would you recommend to use in a routine with CosrX 7% AHA and CosrX 4% BHA. Would the CosrX low ph gel cleanser work?

    • shopichigo says:

      Hi Mathilde, I would not suggest the Cosrx Low pH Good Morning Gel cleanser as that also has salicylic acid in it. You might want to add a moisturizing cleanser in your routine because of your chemical exfoliation. Our personal favorites are the Pure Heals Propolis Foam Cleanser or the Etude House Soon Jung Whip Cleanser 😀

  2. Lainey says:

    Hello! I just recently discovered your blog and I love how informative they are! I used to think that I have a clear understanding on the correct layering of the skincare products that I have but after reading your blog, I’m now a bit baffled. Lol! These are the products I currently have and how I layer them. Please help me check if I’m indeed doing it correctly or not.

    1. I just wash my face thoroughly with water in the morning
    2. COSRX One Step Original Clear Pads
    3. Klairs Freshly Juiced Drop Vitamin C
    4. COSRX Natural BHA Skin Returning A-sol (for spot treatment only; normally in T-Zone area)
    5. COSRX Galactomyces 95 Whitening Power Essence
    6. Mizon Skin Recovery Gel Cream (or other moisturizer that I’m trying out)
    7. Biore UV Aqua Rich Watery Essence SPF50+

    1. Etude house O-LE-MONG Sherbet Cleanser (used only at night time to remove make up & sunscreen)
    2. Hada Labo Whitening Face Wash
    ** I sometimes use Garnier Micellar Water only at night if I’m too tired to do double cleansing.
    3. COSRX One Step Original Clear Pads
    4. COSRX BHA Blackhead Power Liquid (used on alternate days with #5)
    5. COSRX AHA Whitehead Power Liquid (used on alternate days with #4)
    6. COSRX Natural BHA Skin Returning A-sol (for spot treatment only; normally in T-Zone area)
    7. COSRX Galactomyces 95 Whitening Power Essence
    8. Mizon Skin Recovery Gel Cream (or other moisturizer that I’m trying out)
    9. Laneige Water Sleeping Mask (2-3x a week) or 10. Face Mask

    ** I also use Aztec Secret Indian Healing Clay mask once a week after double cleansing. I go straight to #7 PM routine if I do so.

    Btw, is it safe to use A-sol for the whole face and not just as spot treatment? I know my comment is lengthy but I hope you can find time to respond. Thanks!

    • shopichigo says:

      Hello Lainey, Thank you for dropping by on here! You’ve got a pretty set routine there and seem to understand the layering well no worries! From your post I can’t really tell what your skin type or your skincare goals are however based on the acids the routine looks good but maybe a bit drying? The only two suggestions I would make is adding more moisture and skipping the Cosrx pads in the morning. These pads also contain BHA so I would refrain from using them in the morning and just go straight to the Vitamin C or use a more hydrating toner beforehand like the Etude House Soon Jung Toner. Also, waiting 20 min after applying the vitamin C before applying any other skin care item is the way to go, same for the acids in the evening routine. Please let us know if you have any other questions 😀

      ‘xo Ichigo

  3. Sreynich says:

    I’m 20 years old. i want to use product that match my age so, what’s products that i can use.
    I read the detail of each product. some product for 40s 30s so I am afraid that i use the wrong product that I am just 20s and it do’t match my skin type. if i use all this i think my skin will get older

    • shopichigo says:

      Hi there, It’s not so much a matter of which product matches your age but more so which matters your skin type and concerns. Hope that helps 🙂

  4. Lydia says:

    Hi there!
    This post says to put aha/bha after toner, or as a toner, but if that’s the case why are there bha/aha serums? Isn’t putting on the serum at night and then letting the serum do its magic while you sleep also an option?

    • shopichigo says:

      Hi Lydia, there are a variety of different type of products with actives like AHA & BHA including toners, serums and even creams. It’s best to apply these actives to directly to the skin after balancing its pH level. For example you can also use an hydrating/ balancing toner and use your serum with actives after that. Just make sure that you take note of the ingredients of the other products you are using and check if they aren’t in conflict with the actives you are using.

  5. Koh says:

    Hi there,
    Thanks for such n informative write up on usage of acids.. I have never used any acids products in my skincare routine before, my skin its generally clear excpt the t zone n cheeks area which I have a problem with on visible pores, whiteheads n blackheads.

    Can you recommend which or the type acids I should try to incorporate into my routine , something mild yet effective.

  6. Koh says:

    And the sequence of acid application its after say our regular hydrating toner , then acid say the Eg.Corsxr bha then let it seat on for 20 mins, then continue on to the next step of essence/serum, moisturiser it’s that right ?

    Thank so much, would be looking forward to your advice.

  7. Mia says:

    Hi! Is it still necessary to use a chemical peeling gel for exfoliation once/twice a week if you use an essence/serum with AHA + BHA in your evening skincare routine?

    • shopichigo says:

      Hi Mia, if you are properly using your AHA/BHA already there should be no need for an additional peeling gel as both AHA and BHA are already chemical exfoliants 🙂

  8. Samindrika says:

    I m using vitamin c serum in my morning routine and aha/bha in the evening routine. I m a little confused with niacinamide, i m using secret key first treatment essence is it ok to use it after vitamin c in the morning and after aha/bha in the evening?

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