BHAs, aka beta hydroxy acids, are very similar to alpha hydroxy acids (refer to The Beauty Alphabet: A is for AHA!). However, the difference between BHAs and AHAs are the fact that BHAs are LIPID-SOLUBLE. AHAs are 💧 water-soluble.
Because BHAs are lipid-soluble, they have the ability to penetrate into the skin through sebaceous follicles, aka sebum, making it a great ingredient for those with oily skin and open pores and comedones.
Examples of BHAs:
- Salicylic acid — it’s often described as a BHA, but it’s sort of not considered a BHA at the same time. For simplicity, I’m calling it a BHA (can be sourced from white willow bark)
- Sodium salicylate — the salt form of salicylic acid that can be obtained from white willow bark
- Citric acid
- Malic acid
Beta hydroxy acids also have similar chemical structure to alpha hydroxy acids.
What makes it beta and what makes it alpha?
If you’ve taken general or organic chemistry, you probably know about the alpha and beta carbon positions.
Here’s a little snippet from Wikipedia for your understanding of alpha and beta carbon positions:
Structural wise, beta hydroxy acids contain a carboxylic acid functional group and hydroxy functional group separated by two carbon atoms. Alpha hydroxy acids have one carbon separating the two groups.
To make it more simple, beta hydroxy acids have one more carbon. See chemical structure difference highlighted in blue below:
Some beta hydroxy acids can be considered alpha hydroxy acids as they can sometimes contain a hydroxyl group in the alpha position and another one in the beta position. Examples of this phenomenon include: Citric and Malic acid
What all can BHAs do for you?
Beta hydroxy acids are topical exfoliant that can reverse some signs of photo-aging, fine wrinkles, discolored skin, and more. They have similar functionality to AHAs except for its solubility.
Because BHAs are lipid soluble, they can help “unclog” pores through deeper or better penetration much better than the water soluble alpha hydroxy acids. BHAs can reach the plugs that cause lesions to form, so this is a great ingredient for those who are battling acne, pimples, blackheads, and so on.
When using AHAs or BHAs, you must…
WEAR SUNSCREEN/SPF 🧴 !!!!!
You should always wear sunscreen and spf during the day, but it is extremely important to wear it when using AHAs & BHAs!
These ingredients can cause extra sensitivity to the sun, AHAs more than BHAs; therefore, it is imperative to pair AHAs and BHAs with sunscreen and spf during the day.
The best way to decrease sun sensitivity is to use products containing AHAs and BHAs at night and not in the morning or during the day. Again, still wear sunscreen the following day. I recommend a minimum of SPF 30 (heck, even an SPF 15🧴 is better than no SPF!).