Acids Explained: What are AHAs, BHAs and PHAs In Skincare?

Topical acids have been getting more popular over recent years, and it’s with good reason. As everyone’s starting to catch on to the damage that harsh scrubs can do to your face, plus the total glow-inducing, pore-clearing magic of chemical exfoliators, acids are quickly becoming a must-have in skincare routines. They can even help with collagen production, which reduces fine lines and wrinkles!

But with so many different types of acids and products out there, it can be a bit overwhelming if you’re new to the scene or your current product isn’t working for you.

Below, we break down three common types of acids in skincare—AHAs, BHAs and PHAs—plus give our top recommendations for the best products in each category.

WHAT ARE AHAs IN SKINCARE?

Usually derived from organic sugars, alpha hydroxy acids (AHAs) dissolve the bonds keeping dead cells clinging to your skin, revealing a smoother complexion and reducing imperfections.

There are several different types of AHAs you’re probably familiar with, which are great for a number of skin conditions. Glycolic acid is a super popular and widely studied AHA that can help with ageing and acne, while lactic acid reduces dark spots and also helps with fine lines. Mandelic acid, from bitter almonds, also treats the aforementioned conditions, but is super gentle on the skin.

Whether you have uneven texture on your face, mild breakouts, sunburn or your complexion is just looking a little dull, AHAs are a great option to add into your routine.

Check out more about AHAs in our ingredient guide here.

AND SHOP SOME OF THE BEST AHA SKINCARE BELOW:

WHAT IS BHA IN SKINCARE?

Now for more serious breakouts and congestion, let us direct you to beta hydroxy acid (BHA), salicylic acid.

This powerful BHA comes from willow bark and sweet birch, and goes deep into your pores to unclog them and prevent acne. Antibacterial and anti-inflammatory, BHA soothe redness, reduce oiliness and make your pores appear smaller.

Read more about BHA in our ingredient guide here.

HERE ARE OUR PICKS OF THE BEST BHA SKINCARE PRODUCTS:

WHAT ARE PHAs IN SKINCARE?

Polyhydroxy acids (PHAs) are the only acid category in skincare that don’t make your skin more susceptible to UV damage. Incredibly gentle on the skin, they dissolve the protein bonds keeping dead skin attached to your face and improve hydration. While they don’t penetrate the skin very much and therefore aren’t the best for clearing acne, they’re ideal for those with sensitive skin who still want that clean, glowing complexion.

Read more about PHAs in our ingredient guide here.

THEN SHOP THE BEST PHA SKINCARE BELOW:

AHA vs BHA vs PHA: Which should I use?

All of these lovely acids are going to exfoliate your skin and keep it smooth, clear and firm, but as you’ve already gathered, there are differences between them that make each more suited to your particular needs.

AHAs and PHAs only sit on the skin’s surface, so BHAs, which exfoliate both the surface and within pores, are better for serious breakouts, large pores and normal to oily skin.

For normal to dry skin, an AHA is a great choice since you don’t need the super deep exfoliation of a BHA.

Those with easily irritated skin are going to want to reach for a gentle AHA like lactic acid, or a PHA, which is the gentlest of them all thanks its large molecular structure (meaning it can’t penetrate the skin like salicylic acid does). PHAs are also wonderful if you use a retinol, as they work together to brighten the skin.

Can I use AHAs, BHAs and PHAs together?

Technically, yes.

With these acids targeting different conditions, you can definitely layer them to get better results. However, combining acids does make them more potent and can sometimes cause irritation (see the bit about negative side effects below), so just be careful about how you do it.

Experts recommend applying leave-on acids to different parts of the face to avoid layering them on the same area of skin (such as salicylic acid for an oily T-zone and an AHA or PHA product elsewhere), or using a cleanser with one type of acid followed by a toner with another type of acid since the cleanser will be washed off.

Plus, keep in mind that there are other ingredients you definitely don’t want to mix these acids with unless they’re already formulated together, such as vitamin C, so always make sure you do your research before adding a particular product to your routine!

Are there any negative side effects of using topical acids in skincare?

Acids exfoliate the skin, and you probably know by now—if you’re ditching the face scrubs for chemical exfoliators—the dangers of over-exfoliating. That’s why you should always test out an AHA, BHA or PHA product before incorporating it regularly, and plan your layering carefully so you don’t over-use these acids and ruin your skin barrier.

Use of topical acids can also cause sensitivity to sunlight, but that’s easy to fix with a good ole SPF (which you should be wearing daily anyways!).

Once you’ve gotten rid of all those pesky dead skin cells with a chemical exfoliator, you’ll want to follow it with a serum!

Check out our Ultimate Guide to Face Oils and Serums.