Lab notes > Ingredients > AHA and BHA: What are they and how should they be used?

AHA and BHA: What are they and how should they be used?

A guide to using AHA and BHA ingredients

Alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs) are two types of acid found in many chemical exfoliants. Both help to remove dead skin cells from the top layer of your skin, but they work in different ways and each have their own additional benefits.

AHAs work on the surface layer of the skin to dissolve dead skin cells, which in turn can even skin tone, improve radiance and target fine lines - some also have hydrating properties.

BHAs, salicylic acid in particular, have antibacterial properties and are oil-soluble, so can sink deeper into the skin to unclog pores and prevent blackheads and breakouts.

A list of AHA and BHA ingredients you may be familiar with:


  • Glycolic acid
  • Lactic acid
  • Citric acid
  • hydroxycaprylic acid
  • hydroxycaproic acid


  • Salicylic acid (or related ingredients like willow bark extract)

It’s important to note that due to their exfoliating nature, either form may irritate your skin, bring on redness, or make you more likely to get a sunburn, so it’s important to choose the right product for your skin and introduce it as directed. That being said, if you have very sensitive and reactive skin or plan on going away any time soon, it might not be the best time to introduce an AHA or BHA product into your skincare routine.

It’s always a good idea to talk to our aestheticians before you introduce any new products. They can let you know if it’s right for you, whether it could affect the success of your current routine and what strength or concentration of the ingredient is best suited to your needs.

Using AHA and BHA Together

AHAs and BHAs are used for treating different skin challenges, and are often suitable for different skin types. AHAs might be best for less congested skin, looking to improve radiance and even tone, where BHAs tend to work best for those with oilier skin that’s prone to congestion.

More frequently, we’re seeing products using both AHA and BHA together. It’s worth nothing that these usually have a gentler formulation of both, so are deemed safer on the skin. Gentler yet still powerhouse products for evening out your complexion, making the skin smoother and stimulating the skin to produce new skin cells faster.

Understanding which exfoliant is right for you (if at all) can be confusing, so we want to really reiterate here that you should talk to our skin care specialists before you go ahead and introduce any new products into your routine. If AHA or BHA is advised, it’s important to follow instructions carefully. Usually, this would be to phase the ingredient into your routine, using 1-2x per week and building up over several weeks to daily use (as a maximum).

We see so many different crazes and miracle ingredients out there that it’s hard not to want to try it all, but overuse of any acid can really affect your skin barrier health over time. If your skin starts to feel red, irritated, itchy or you see sudden breakouts at any point during the use of exfoliants, it’s important to stop the use of any active ingredients and focus on healing the skin barrier. Sometimes it’s better to keep your skincare simple.

How to Use AHAs or BHAs Safely

Take some simple steps to protect your skin: 

  • Introduce them slowly – your skin is always changing and will build up a tolerance, so start with a small amount of product, 1-2 times per week. This will be enough for your skin to get familiar with the ingredients.
  • That being said, follow the recommended use and try not to be tempted into using more than you need. Our aestheticians will let you know how often and how much of the product to use.
  • Use an SPF on your face every single day (yes, that’s right) after your moisturiser, even if you are spending the day indoors. 
  • If your skin tends to be reactive, do a patch test before use. Put a little bit of the product on a small area of your skin first (behind the ear or inner wrist.) If your skin is fine 24 hours later, you can proceed to using the product as advised. If you notice any type of reaction (look out for heat, redness, itching, irritation and so on), avoid using the product and speak to our skin specialists.

We want you to love being in your bare skin and understand that your skin health is part of your overall health and wellbeing.

Take our skin health quiz as a first step in receiving your personal routine and even book in to speak to one of our aestheticians at a time that suits you.


AHA and BHA for Skin: What to Know ( 

AHA vs BHA: The difference and how to use both (

AHA and BHA – What Is the Difference and How to Use Them in Skincare (

AHA vs. BHA: Choosing an Exfoliant, Acid Types, Products (


Pippa Harman
Pippa Harman
Co-Founder Renude