Inspiration, Solutions & Expert Advice

The Beauty Memo

Acid Layering 101: The Experts Guide

Whether you’re already signed up to the “skincare acid fan club” and you use acids in your daily routine, or you’re slowly trying to figure out which acids work best for you, one of the most important things you need to know when it comes to incorporating acids into your skincare routine is how to layer them. From skincare guru Hyram Yarbro to flawless celebs such as Hailey Bieber, everyone is talking about (and loving) skincare acids!

Acids, such as hyaluronic acid, lactic acid, salicylic acid, and glycolic acid, have really gained popularity in the last few years, and for good reason! Acids are incredibly powerful and provide a wide range of benefits - they can fight signs of visible aging, reduce inflammation, ward off and help to cure acne, and even skin tone, as well as reduce scarring.  

Although it’s obviously amazing that acids are so powerful, you can’t just go piling on different acids onto your skin for this very reason - you need to take great care when choosing acids, applying acids, and mixing different types of acids. If you don’t, you could cause severe damage to your skin, and no one wants that, so, listen up! 

In this article, we’re going to be diving deep into the world of acids, giving you a complete acid 101, covering the different types of acids, which acids you should use, and how you can perfectly layer acids so that they work with you rather than against you. 

The Main Types of Acids – AHAs, BHAs & PHAs

Although there are lots of different types of acids, most acids tend to fall into three categories - AHAs (alpha-hydroxy acids) and BHAs (beta-hydroxy acids) and PHAs (Poly Hydroxy Acids). Each acid is used to exfoliate the skin, but each type works differently and appeals to different skin types. 


AHAs are acids that are water-soluble and naturally occurring in fruits and milk. These acids exfoliate the skin by penetrating the surface of the skin, breaking up and removing dead skin cells, and encouraging new skin cells to be generated. Much like after physical exfoliation, you will notice that after using AHAs your skin is much smoother. AHAs are typically recommended for those with normal to dry skin, those that are frequently exposed to the sun, and may suffer from pigmented or an uneven skin tone. AHAs are highly recommended for ages 30 and above. This is because AHAs specifically exfoliate the skin whilst increasing the moisture levels, helping to reduce visible signs of aging. Dr Ife J Rodney, CEO of Eternal Dermatology and Aesthetics in Maryland states that, "AHAs work by helping to break the bonds between surface skin cells in order to increase peeling and cell turnover, as well as stimulate collagen production in deep skin layers, resulting in more youthful, radiant-looking skin with better texture”. 

The two most common AHAs are Glycolic Acid and Lactic Acid. However, you’ll also find Mandelic Acid, Malic Acid, Tartaric Acid and Citric Acid within the AHA family. 



BHAs are acids that are oil-soluble and naturally occurring in certain trees. These types of acids exfoliate the skin and penetrate a lot deeper than AHAs, working within the epidermis layer of the skin. BHAs draw out oil and unclog pores by removing excess dead skin cells and sebum. Although BHAs also help the skin to appear smoother as AHAs do, the real benefit of these types of acids is that they promote clear skin and reduce the likelihood of breakouts. BHAs are typically recommended for those with oily, blemished, and acne-prone skin.  BHAs reduce the likelihood and severity of breakouts, reduce inflammation, and kill bacteria that cause skin problems. In addition, BHAs don’t have humectant properties (they don’t help retain moisture), and therefore they’re perfect for those with oily skin! 

The only BHA out there is Salicylic Acid



Poly Hydroxy Acids (PHAs) are bigger molecular acids, meaning they don’t penetrate deep into the skin as AHAs and BHAs do. Instead, PHAs gently exfoliate the top layer of the skin and help to even the texture of the skin, remove fine lines and dark spots.  PHAs are much more suitable for people with more sensitive skin as they don’t exfoliate the skin in the way that AHAs and BHAs do, and therefore, it’s much more likely that they will irritate the skin.  

The most common PHAs are GalactoseLactobionic Acid, and Gluconolactone.  

It’s Also Worth Mentioning Hyaluronic Acid!

Neither AHA nor BHA, hyaluronic acid is a popular acid that nourishes, hydrates, and reduces visible signs of aging. This is a commonly used ingredient in the skincare industry and can typically be found in moisturizers and serums. This is safe to use with pretty much every skincare ingredient and is especially great to use with both AHAs and BHAs!  

Can You Use AHAs and BHAs Together?

You can use AHAs and BHAs together. However, you need to be careful when doing so, because if you overdo it, you can seriously irritate your skin. It’s actually best if you alternate the use of them. For example, if you’re planning on using an AHA, such as glycolic acid, and a BHA, such as salicylic acid, there’s no problem in doing so, but use them at different times during the day. For example, use a BHA in the morning and AHA at night, to avoid doubling up on the acids and irritating your skin. 

Or, you could use an AHA one day, and a BHA the next - alternate the products how you see fit, but try to avoid actually applying them to your face together. 

What about PHAs, AHAs and BHAs?

You can use PHAs with AHAs and BHAs due to the fact that they don’t work deep into the skin and act on the surface level of the skin instead. However, most people that use PHAs are those with sensitive skin, and therefore those people may want to avoid using AHAs, BHAs and PHAs together at the same time as the combination may irritate the skin. Instead, you could use an AHA one day, and a BHA the next, then a PHA after that, or alternative times during the day. If you are using all of these acids, alternate the products how you see fit and see what works for your skin. 

Which Acids Can You Use Retinol With?

Retinol is a popular, extremely powerful skincare ingredient, and a lot of people tend to rush into using acids alongside retinol in the hopes of getting the best skincare results possible. However, this is where it tends to go wrong!  

Retinol should not be used with AHAs, BHAs, or PHAs. In fact, New York Board Certified Dermatologist, Dr. Shari Marchbein states that using retinol with these acids may cause “excessive skin sensitivity, irritation, and redness”. However, hyaluronic acid can be used together with retinol and will actually benefit the skin by giving it moisture, so use this pairing for great results! 

Which Acids Can You Use Vitamin C With?

Vitamin C is another popular skincare ingredient that brightens skin and reduces pigmentation, and people are going crazy about it! However, as wonderful as AHAs, BHAs, and Vitamin C all are individually, they shouldn’t be mixed together! 

As vitamin C has exfoliating properties, using it alongside AHAs, BHAs, and PHAs will irritate the skin. In fact, the combination of Vitamin C and retinol should also be avoided completely. However, trusty hyaluronic acid can be paired with vitamin C and may even improve the efficacy of it!  

It’s All About SPF!

SPF should always be worn during the day (yes, always!), but it’s even more important when you’re using AHAs, BHAs, retinol, hyaluronic acid, and vitamin C. Using acids, and in particular powerful vitamins such as retinol and vitamin C, breaks down your skin barrier and therefore you need to protect your skin from sun rays even more than normal to ensure you don’t succumb to skin damage.   

So, get yourself a high-quality SPF and don’t forget to apply daily, especially when using acids and vitamins as part of your daily skincare routine. 

How Should You Add Acids into Your Skincare Routine?

AHAs and BHAs are most commonly found in toners and serums, so that’s where you should be adding these acids into your skincare routine. Of course, follow the rules set out above and make sure you don’t mix anything that’s incompatible. 

It's important to say that when you receive your acid products and vitamin serums, don’t go overboard and apply them to your skin in large doses straight away, especially if you’ve never used these types of skincare products before. Instead, start by using a low percentage formula only a few times a week. Then, if your skin tolerates it and is reacting well to it, you can up the amount you apply and perhaps even choose a higher percentage formula.  

This is what your skincare routine should look like if using acid products and vitamin serums: 

1. Cleanse (Double Cleanse) 

2. Toner (Add AHA/BHA Here) 

3. Serums (Add AHA/BHA Here, or Vitamin C If Not Using AHA/BHA) 

4. Retinol (Only at Night and If Not Using AHA/BHA) 

5. Eye Cream 

6. Moisturizer (Could Be A Hyaluronic Acid Moisturizer Here) 

7. SPF (Always with your Morning Routine) 

Now You’re Ready to Finesse Your Skincare Routine!

Now you know everything there is to know about different acids and how to layer acids, get out there and give them a go! Just remember, take time when trying new products on your skin, don’t go overboard, follow the rules, and if something doesn’t feel or look right, stop doing what you’re doing and seek professional advice!