Heroin of Cosmetology: Facial Acids

Prior to writing the facial skin care series I was sure that acids are dangerous and harmful to the skin. I was not ready to hear a word suggesting the benefits associated with facial acids use; however, for the sake of the fair representation of information I had to learn about them. For those who are skeptical or simply does not know much about facial acids, here is the introduction to the types of facial acids, their relationship with pH and safety advice (as related to frequency of use and product combinations).

Acids are some of the most beneficial ingredients available in skin care when used in right concentration and mix. They are the miracle tools to fight acne, wrinkles, age spots, scarring and uneven tone. However, currently there are so many acids on the market that it can be overwhelming to know and remember which one to use. As such, let’s first explore the types of acids used in facial skincare products.

Types of facial acids

  1. Exfoliation and anti-inflammatory acids
Decoded abbreviation Poly hydroxy acid Alpha hydroxy acid Beta hydroxyl acid
Solubility Water soluble Water soluble Oil soluble
Function Exfoliant Exfoliant Exfoliant + unclog   pores
Pros Gentler than AHAs Gentler than BHAs Penetrate deep into the skin
Cons Might be too light for some people to see the difference Exfoliate only the surface of the skin Might cause skin irritation and sensitivity
Suitable for Very sensitive skin Dry / Sensitive skin Oily / Acne prone skin


  1. Moisturizing vs exfoliating acids:
Decoded abbreviation Hyaluronic acid Alpha Hydroxy Acid
Function Moisturizer Exfoliant
Be aware: Main lubricant in the skin and joints  


How to access strength of facial acid product?

In order to understand the strength of your acid product you need to know “Free Acid Value” of the product which is based on:

–          acid percentage in the product

–          pH of the product


When it comes to active ingredients, it is worth knowing that they are pH – dependent. The top layer of our skin (the stratum corneum) is oily which means that, in order to penetrate deeper into the skin, the hydroxyl acids need to be in their uncharged, free acid form … which we can control by means of pH. To be more specific, the lower the pH, the more “free” the acid is to do the job it is designed to do. As such, facial acid products formulated at pH below 2.0 level are the ones where all of the mentioned acid percentage is essentially “free” / completely unrestrained to do everything it is designed to do on the skin. For example, if you have a product which is a 10% lactic acid product formulated at pH of 2, then all 10% of lactic acid will actually work.


The tricky part here is that:

           If the pH is too high, the acid would not penetrate the skin even at a higher concentration;

          If pH is too low, you run a of risk of irritation at the minimum. In more severe cases, people suffered substantial chemical burns and long – lasting damage to the skin.

As such, do educate yourself about facial acids in order to use them safely. Also, when you are looking for a facial acid product, it is best that you choose the one that indicates pH level as well as acid concentration so that you can work out what the tradeoffs are before buying something and wondering why it did what it did.



Facial acid safety guideline


pH Less than 4 Less than 3.5
Concentration 4- 10% 1 – 2%
Do be aware that each HA has different potency. Consider the above information as a general guideline and consider each facial acid you would like to use


What is the product is formulated at a slightly higher pH i.e. 3.5 – 5.4?

As mentioned above, Free Acid Value is an indicator of strength of the facial acid and how much of it is actually available to do the job it is designed to perform. However, what happens if the product is formulated at a slightly higher pH and not all of the mentioned acid is readily available to “work”?Does the unabsorbed acid just sit on top of your skin shut out forever?

The answer is NO because the acid likes to be a certain percent free acid at all times.Now that the free acid is gone, the space is vacated for some of the disassociated ions to become uncharged free acid which can eventually go through the skin as well.Theoretically, at any pH, all of the HA could turn to uncharged free acid and will be absorbed given the time. This is the reason why some HA products formulated at higher pHs are said to be time – release ( products where active ingredients sit on top of the skin and slowly turn into absorbable free acids over time instead of being absorbed right away). Such products provide users with benefits of decreased irritation due to too much of the facial acid and from the low pH.

However, it is important to keep in mind that if pH is too high, the HAs will be absorbed too slowly and will end up too dilute in your skin to have any effect.

As we speak about timing of facial acid absorption, it would be appropriate to cover some information related to application of facial acids.



Order and timing of application of facial acids

General rule of thumb is to wait 20 – 30 minutes between application of facial acids and other low-pH dependent ingredients in order for each acid to have time to do its job.

Wait 20 minutes between application of each facial acid
–     20 minutes is a window allowing each facial acid to do its work and each acid’s pH will be effectively neutralized by the skin

–  20 minutes wait will ensure that products do not mix so they don’t cancel each other out or cause reactionary breakouts

–     Avoid product interference

For example, facial acids will be interrupted by the action of serum. While serum might not be able to do the job due to facial acid formulation


1)      Cleanser + Toner (?)

2)      Vitamin C

3)      Wait 20 minutes

4)      BHA

5)      Wait 20 min

6)      AHA

7)      Wait 20 minutes

8)      Apply the rest of your routine



Facial acids and frequency of use

ü  There are people who use exfoliating acids on daily basis. My skin is fairly thin so such practice is not for me

ü  There are suggestions to use exfoliation minimum once a week and maximum twice a week in order to avoid the problem of clogged pores and buildup of dead skin cells. The idea here is that you should not exfoliate already inflamed skin. You should support your skin with maintenance exfoliation so it does not even go into the inflammation stage

ü  Do not use facial acids on daily basis! Research continues to show that when the skin is exfoliated daily, the inflammation created – even if it is not visible – can accelerate the aging process. For the best results, it is suggested that exfoliating acids are used 3 nights on and 3 nights off. For example, during the first 3 nights you could use products with exfoliating acids and follow up with 3 nights of hydration and antioxidant rich products. The idea behind such suggestion is that after 3 nights, when the skin is well exfoliated, use hydrating products to feed the “new” cells with nourishing performance ingredients like fermented ingredients and antioxidants.

Once you decide on the desired frequency of use of exfoliating acids, make sure your products support that direction. It is critical to read, fully understand and follow the instructions of the particular product you have chosen to do the job!

Also, even if your skin never looks red or visibly irritated, inflammation is one of the underlying causes of aging. Overuse of exfoliating acids might cause deep and not openly visible inflammation in the skin which means that acids will work against your intention to achieve younger looking skin. Do use treatment products, masks and moisturizers with antioxidants and calming ingredients such as green tea, white tea, chamomile, algae extract, licorice extract, etc.


General guidelines for safe and efficient use of facial acids

ü  First and foremost, Perform a patch test!

If you have sensitive skin, you are no stranger to the practice of testing the products prior to using them. Patch tests are particularly important when it comes to exfoliating acids!

The best place for patch testing on the face is near the ear: if you develop redness or irritation, this area can be easily hidden. That said, keep in mind that sometimes skin has slower reaction time so it might take few days for the irritation to surface

ü   Tingling sensation on the skin is normal but it should subside shortly after the application of a moisturizer. If the tingling turns to pain, wash the product off immediately

ü  Acid product is only as potent as the free acid compound that is flowing around. pH level of the product will determine the amount of the acid in it. Too much of acid content will leave the skin red and stinging. Too little acid will make the product absolutely ineffective. AHA and BHA products will be most effective when their pH level is between 3 and 4


ü  It is suggested that your skin will gain the most benefit from AHA and BHA products when you are in your 20s and 30s. You can still use them as you mature; however, the results will not be as prominent. In your 40+, you might want to opt for prescription strength retinoids. Also, AHA and BHA products do not address deep wrinkles and lines which is the job of fillers and laser treatments


ü  Do understand that you are working with acids so start slow and start with products that contain lower percentage of the acid. Also, acid based products work best when you pH adjust with the toner. That said please do keep in mind that pH adjusting is said to make acids more potent and skin more sensitive to them. As such, please exercise good degree of caution when using acid based products


ü  Acids increase skin’s sensitivity to the sun. As such, acids that are left on the skin for extended period of time like serums and moisturizers should be used only at night. In fact, acids yield better results at night since the skin is primed for repair mode

ü  Acids increase your skin’s sensitivity to the sun by 50%. As such, facial acids are best to be used as part of the evening routine. Also, never, NeVeR forget to use SPF during the day!!!!



Safety alert: Facial acid mixes to avoid

 Retinol with AHA / BHA products  When used together, they are very likely to cause redness and irritation  It is best to use them at different times of the day or week
 Retinol and Ascorbic Acid (Vitamin C)  Retinol works best at pH level of 5.5 – 6. Vitamin C works best at pH of 3.5 and lower. It is impossible to formulate a product where they would work together  If you use them both at the same time, you are wasting a product
 Niacinamide and Vitamin C Niacinamide “kills” potency of Vitamin C. Also, the combination of the two makes the skin flush (i.e. causes redness)… It is best to use them during different times of the day or week
AHAs and Vitamin C AHAs change the pH of Vitamin C enough to destabilize it

Vitamin C is extremely unstable! It is a product that is very pH dependent. It easily goes rancid upon exposure to light and air



How can I increase potency of facial acids?

pH adjust with toners Skin is said to be most receptive as well as most sensitive to acids. Be cautious


Choose products which combine AHAs / BHAs with amino acids (ex. Arginine) Such product formulations are less irritating for the skin due to reduced speed of penetration of the acid into the skin


Use calming ingredients


Do not overuse




For more information regarding pH balanced skin care, please refer to the following post: 

Epidermal Sweet Spot: pH balanced Skin Care Routine


Thanks for reading,



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