What’s The Difference Between AHA vs. BHA Exfoliants

It’s likely you’ve heard about the different types of acids in skincare, and then shortly after felt a headache coming on! There are SO many, it can be difficult to work out which would suit your skin type best. Worry not, this article will break down everything you need to know to make an informed choice.

Within the skincare market there are many, many types of acids we can use, with Alpha Hydroxy Acids and Beta Hydroxy Acids being the most popular categories! Both work to exfoliate your skin, but due to their different chemical properties, they act in completely different ways. 

So why should we exfoliate skin? Every day, our skin goes through a natural exfoliation process anyway – but using an exfoliating acid helps to speed up this process. It can help with a whole range of skin concerns, such as acne, hyperpigmentation and fine lines. 

What is an Alpha Hydroxy Acid?

AHA’s are water-soluble, which means they sit at the surface of your skin, and (depending on the size of the molecule) will penetrate the outer skin layers. So, how do AHA’s work? They work by dissolving the ‘glue’ which holds dead skin cells together, which allows these cells to fall away from the skin surface much more easily, revealing the fresh skin cells!

Benefits of AHA’s

  • As AHA’s speed up exfoliation, they will help to reduce the chances of pores clogging with dead skin cells, hence reducing pimples forming
  • The exfoliation helps to enhance how glowy your skin will look, as skin often looks dull due to dead skin cells sitting at its surface!
  • AHA’s also help to stimulate collagen production, meaning AHA’s also work really well for more mature skin which may have fine lines. This increased collagen production (which will require long term commitment, you won’t see lines softened overnight!) will help to plump up skin, diminishing fine lines. 

Risks of AHA’s

  • AHA’s can be quite strong, so it’s important to choose the right type of AHA for you, at the right concentration. AHA products can vary greatly, from serums which you won’t feel upon application, up to serums which have a higher concentration and can make your skin sting – especially if you haven’t used them before
  • Any exfoliating acid use should be built up slowly, with my recommendation being use it once a week for a few weeks, then build up slowly to 2-3 times a week (depending on which other products you have in your routine already!)
  • If you have sensitive skin it’s very important to do two things. Firstly you should pick a gentle AHA (read more below) which often comes in a creamier form. It’s also important to do a patch test, by using a small amount of product on the jaw area. Leave this overnight and see how your skin reacts – any form of intense redness or itching will signal this product isn’t for you. 
  • As AHA’s speed up cell exfoliation, it makes your skin more sensitive to the sun, which makes it even more important to wear sunscreen. Not doing this increases both your skin cancer risk, as well as hyperpigmentation ‘sun spots’ forming. 

Types of AHA

AHA’s are just the overall name for a group of chemicals which are all similar, but have different sizes. A bigger sized AHA cannot penetrate the skin as well as a smaller one – which means the bigger one is less likely to cause irritation (but it also won’t have as drastic results!) The list below outlines different types of popular AHA’s in skincare:

  1. Glycolic : The smallest AHA, meaning it can penetrate deep into the skin layers – it’s often chosen within professional skin treatments at higher concentrations to target more severe skin concerns. Personally I don’t reach for this acid often, unless it’s in a blend with other, more gentle AHA’s. Glycolic acid is derived from sugar cane.
  2. Lactic : A larger size than glycolic, meaning it is more gentle. It’s often used for treating hyperpigmentation as you can normally use it more often, when compared to glycolic acid. It is derived from milk.
  3. Mandelic : Another larger size AHA, derived from almonds! This is probably my personal favorite – it’s gentle but works very well! 
  4. Citric – Derived from citrus fruits (as you may have guessed!) and has been shown to improve moisture levels; so you’ll get multiple benefits from this ingredient.

What is a Beta Hydroxy Acid?

BHA’s are oil-soluble, meaning they dive deeper into your pores than an AHA would be able to. They work by dissolving the ‘glue’ holding skin cells together – just like AHAs, but specifically target the lining of the pore. This makes them great for refining pore size, and for anyone who has an oily skin type. 

Benefits of BHA’s

  • Due to the exfoliating nature, application of a BHA product helps to reduce congestion and pimple formation. As they can work within the pores, BHA’s will help break down blackheads and also reduce the likelihood of them recurring. Pores look smaller, as there is less debris clogging them.
  • BHA is also a natural anti-inflammatory, as well as anti-bacterial – which is why it’s a gold-standard ingredient for treatment of acne. Together, these features help to reduce the size and frequency of acne breakouts

Risks of BHA’s

  • As with AHA’s, any exfoliating acid has the potential to be irritating. To minimize this risk, the BHA product should be patch tested, use built-up slowly over time, and a lower percentage of product chosen initially. Irritation occurs as the skin barrier becomes damaged – each of the above tips to minimize irritation will ensure the skin barrier is well protected
  • BHA’s also make the skin more sensitive to sunlight, making wearing sunscreen even more important.
  • Due to the oil-soluble nature of BHA, it tends to dry skin out. This normally doesn’t negatively impact oily skin, as less oil is actually preferable during treatment. However, overuse of BHAs can cause dryness and flaking of skin in those with oily skin, and sometimes general use of a BHA is enough to impact anyone with dry skin. I would advise using a product which is creamier, and more nourishing if skin is already dry. 

Types of BHA’s

  1. Salicylic acid : This is the most common BHA, and usually what you’ll find in anti-blemish products. It’s been shown to work well at calming down skin, and acts in an anti-inflammatory way – this makes it perfect for red, bumpy skin
  2. Willow bark : A naturally occurring ingredient, which contains salicin. Salicin has been shown to convert to Salicylic acid in the body – hence Willow bark is a natural source of salicylic acid. This is why it’s often used in more natural skincare products which are targeted for acne.

How to add AHA and BHA’s into your skincare regime

If you already have a skincare routine, you may be wondering how to combine all of the products together – as some don’t mix well! Whenever you use an exfoliating acid I would avoid retinol, benzoyl peroxide or vitamin C in the same routine – they’re what we call ‘actives’ as mixing them together can often cause more irritation. Try some of the sample routines below 

Morning routineEvening routine
AHA / BHARetinol 
Vitamin CAHA / BHA
AHA / BHABenzoyl peroxide

It is fine to use hydrating or nourishing ingredients in the same routine as any of the above actives, as they are unlikely to cause irritation. Examples of these ingredients are hyaluronic acid, polyglutamic acid, niacinamide or ceramides. 

As mentioned before, when you add a new exfoliating acid into your skincare regime, you need to both patch test, and slowly introduce it until you are confident your skin reacts well to it. 


Is AHA or BHA better for exfoliating acne-prone skin?

BHA’s are my personal preference for my acne-prone skin, as they can penetrate the skin more deeply and break down the debris inside the pores. This debris is often the cause for congestion, whilst the BHA’s anti-inflammatory impact is also a huge benefit for acne-prone skin.

Should AHA or BHA be applied to skin first?

I would always apply BHA, as it can get deeper into the pores – whereas AHA’s will sit at the surface. If you wish to apply both together, purchase a product that already blends them for you – you’ll get much better results

Originally Published: November 16, 2022

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Analyzed by Beth Cooper
I'm a beauty content creator from the UK, on both Instagram and TikTok. I adore exploring new beauty products, whilst also learning the science behind the skincare (I'm a major science nerd - currently studying a Bachelors Degree in Health Sciences!) I'm passionate about making acne care accessible for all, whilst empowering people to feel like they are good enough and beautiful with or without their acne. It's such a complex condition, so getting good information to people is so important to me, years of those horrendous internet DIYs really damaged my skin! Read more of Beth's articles.

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