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Hydroxy Acids


It has taken me waaaaay too long to finally start this series on my blog, but I am glad I am finally starting. Before I started my current job, I was constantly reading about cosmetic ingredients and learning about how to formulate the best skincare products. I love teaching my friends about how marketing works against science 99% of the time in the cosmetic industry, especially when a new fad ingredients is discovered (*cough cough* hyaluronic acid *cough cough*). So since they seem to like learning/knowing these things, I wanted to share what I know with everyone else who reads COS. Most bloggers give advice about their skincare routine, but I am yet to see any that actually know about the ingredients they’re using. I know that most people could care less about what is in their products so long as it makes their skin look new & shiny, but I know there are several people who are starting to be aware of what is in what they use daily.

My goal is to create a skincare dictionary, if you will. I will try to breakdown all the fad ingredients and tell y’all whether or not a product is worth splurging on based on the ingredients. Of course all my thoughts are opinions (backed by science), but they will be as unbiased as possible. So at the end of the day, it is up to you on whether or not you take my advice.

The first topic in my ingredient dictionary will be hydroxy acids!

What is a hydroxy acid?

They are a class of molecules that contain a carboxylic acid + hydroxyl group. There are 2 main different types: alpha & beta. The different acids are names based on how far their hydroxyl group (-OH) falls from the carboxylic acid group (-COOH).

That is probably not the clearest non-scientific definition, but that is the best I can do ha ha.

When most people think of acids, they probably think of burning. This is mainly because in school we are warned about the dangers of strong acids and the damage they can do to any cell on our body. Hydroxy acids are capable of doing that same damage, but in the proper concentrations, they can become your skin’s BFF.

When I was still formulating skincare products, I would try to keep all my products acidic. Most sources state that the pH of human skin is around 5-6, but in reality, it is in the range of 4.0-5.5. So what does that mean? Basically, when we use products that are closer to our skin’s natural pH, our skin does not need to work hard to try to get back to it’s optimal pH level. Products that have very high pH, like soaps, dry out our skin. And as you might have read or heard, dry skin = wrinkled skin. Other than that, when our skin is dry, we are more prone to bacterial invasion along with other issues like breakouts & excess oiliness. Yes, that’s right, if you have oily skin, it’s best to not try to dry out your skin because it becomes counter-intuitive. Anyway, let’s move on. This is a very long post!

What is pH?

pH is simply the -log of the concentration of free hydrogen ions (H) in a solution. It is honestly more complicated than that, but this is not a chemistry course. The amount of H+ in solution is what determines the pH of that solution. So on a pH scale (0-14), a low pH indicates an acidic solution while a high pH indicates a basic solution.

pH = -log10 [H+]

Okay, so now that we’re done with the basics, I can explain why hydroxy acids are the best, when used responsibly.


If y’all read my first post about skincare, you’ll recall that our skin is made up of several layers. Hydroxy acids, AHAs to be specific, work very well to chemically exfoliate the top layer of our skin. Therefore they are less abraisve than scrubs. Out of all the AHAs, glycolic acid is the smallest and due to this, it is the most powerful. This is because structure = function. Skin our skin cells are comprised of fatty/hydrophobic cells and AHAs are hydrophilic compounds, therefore, the two don’t typically interact well. Think of it like this: If you’re stuck in traffic and let’s say you’re driving a pick-up, it’s much more difficult for you to be able to maneuver through the lanes without getting into an accident. If you were driving a motorcycle, you could go in between lanes and basically cut your way though the traffic to make it to your destination. So that is how glycolic acid works. Since it is smaller than the rest of its family members (the AHA family), it has an easier time penetrating our epidermis. Other AHAs have benefits as well, and I will discuss each of them separately in the future. But for now, I just want to introduce the entire class of hydroxy acids.

Image result for glycolic acid structure


Another hydroxy acid that is probably familiar to y’all is salicylic acid (a beta hydroxy acid – BHA). Salicylic acid is another popular acid. The difference with this acid is the fact that it has more hydrophobicity, therefore it penetrates deeper into our skin than an AHA like glycolic acid. This enables it to get deeper into pores, which is why chemists & dermatologists love to prescribe products that use this ingredient for acne. This is kind of a pet peeve of mine though because several studies have determined that salicylic acid does not kill p. acnes (a bacteria that causes acne), yet it is used because it cleanses pores. Personally, in the face wash I formulated, I did not use salicylic acid as an ingredient and it works for people have acne. But I also am not a doctor nor do I sell my products, so I cannot say too much about this.

Skeletal formula of salicylic acid

There are other classes of hydroxy acids, but they are less common. I will still have a separate post for them in the future, but AHAs & BHAs are the ones you will most-likely run into when purchasing products.


Just as I mentioned before, acids can & will hurt you if you do not use them responsibly. It is very important that when you try out any acidic product for the first time, that you test it on the back of your hand first. If there is any immediate burning, stinging, or itching, don’t put it on your face. This should not happen with products that are sold in store, but people who are impatient and want results right away can try to make their own concoctions based on some blog they read (I do NOT recommend this). I have seen many images of people burning their skin and worsening their hyperpigmentation just because they did not seek professional help or they did not want to wait months for the problems to go away.

If you do get a chemical peel from a professional, make sure you do your research. Chemical peels can be very effective, but in the wrong hands, they can be destructive. The percentage of acids in chemical peels are much much higher than what you can buy in stores. But again, I will get into this topic later. I do not want this post to be too saturated with information.

Lastly, when using hydroxy acids (or any other skin sensitizer), make sure to wear sunscreen! I only recommend mineral sunscreens, but you can do your own research and decide whether or not you care about the ingredients in chemical sunscreens or not. Again, this is for a future topic of discussion.

Until then though, I hope I covered everything & if I didn’t, please leave a comment & I’d be happy to answer any questions 🙂 I have also linked some great products below that use glycolic acid. I personally love Tula’s “Pro-Glycolic” gel & I have seen a huge difference in my skin since I started using it a month ago.

Thank you for reading,

bisous bisous ♥

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