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difference between aha and bha

The secret to radiant, younger-looking skin? Exfoliation. If you’re serious about getting your best skin ever, this is a step you can’t miss in your routine. But how to do it right? For a long time, I thought exfoliating skin was easy. Pick a scrub. Use it. Done. Problem was, that often left my skin red and irritated. 🙁

Then, an angel suggested I try chemical exfoliants. But, there was a problem with those, too. No, it’s not because they’re chemicals. Some chemicals are good (water, anyone?). Nope, chemical exfoliants talked a language I didn’t understand. AHAs? BHA? WTH? How is a girl supposed to make sense of all that? Like, can’t someone just start talking plain English and tell you what you have to use, please?

It took me a moment (or three!) to figure out the language of exfoliants and what I discovered changed my skin forever. AHAs and BHA are the only two types of exfoliants that I recommend to my clients these days. But they can’t be used interchangeably. AHAs and BHA have different properties that suit different skin types and needs. So how do you know which one is right for you? Fret not, I answer all your questions in this quick guide:

the ordinary glycolic acid toning solution

What Are AHAs?

AHAs is short for alpha hydroxy acids. I know, that’s not much help. Let me start again. AHAs are acids derived from sugar, milk, nuts and fruits. This is why they’re often referred to as fruit acids. Some brands will go even as far as put fruit extract in an exfoliant, instead of the acid itself, claiming it can exfoliate skin (spoiler: it can’t. You need a certain % of the acid itself to do the exfoliating job. Just saying…). The most common types of AHAs used in skincare products are:

  • Citric acid: Derived from citrus fruits or yeast fermentation, it has mild exfoliation properties. It’s mostly used in skincare products to adjust their pH instead of exfoliating skin. How can you tell? When it’s used as exfoliant, you’ll find it at the top of the ingredient list. When used as a pH adjuster, it’s at the bottom.
  • Glycolic acid: Derived from sugar cane, it’s the smallest of the AHAs. This allows it to penetrate skin deeper than other acids. Translation: it works better and faster. It’s perfect for dry and dehydrated skin.
  • Lactic acid: Derived mostly from sugar acne, it’s the largest of the AHAs. It gives results, but more slowly than other acids. This makes it ideal for sensitive skin that can’t tolerate other exfoliating acids.
  • Mandelic acid: Derived from bitter almonds, it’s mostly been studied to treat acne (although it’s not the best acid for that job).

The Benefits Of AHAs

AHAs are powerful multitaskers. For starters, they exfoliate skin by dissolving the glue that holds skin cells together. “AHAs exert benefits both to the outer layer of the skin (epidermis) and the deep layer (the dermis),” says board-certified dermatologist Kenneth Howe. “In the epidermis, AHAs have an exfoliative effect, increasing the shedding of dead skin cells retained at the surface. They do this by gently cleaving the retained bonds between dead skin cells. Once cut loose, those cells can then fall off, or exfoliate.” Plus, by shedding away old, uneven-toned skin cells, and replacing them with newer, more even-toned eyes, they help dark spots fade away faster.

Another benefit? AHAs boost the production of collagen, the protein that keeps skin firm. “AHAs do this both by increasing collagen synthesis by fibroblasts (the collagen-producing cells in the skin), and by decreasing degradation of the existing dermal matrix,” continues Dr Kenneth. The more collagen your skin has, the smaller your wrinkles are. Finally, AHAs also hydrate skin, making them ideal for dry skin types. 

Who Should Use AHAs?

As a rule of thumb, AHAs are suitable for dry skin. Which one you choose, though, depends on several factors. Here’s a quick guide to help you pick the right one immediately without having to figure things out on your own:

  • Citric acid: I don’t recommend this as an exfoliant. There are better options around.
  • Glycolic acid: Dry skin and anyone who wants to fade dark spots (and isn’t affected by acne).
  • Lactic acid: Sensitive skin that can’t tolerate other acids.
  • Mandelic acid: Acne-prone skin that can’t tolerate salicylic acid (BHA).

Struggling to put together a skincare routine that minimises wrinkles, prevents premature aging, and gives your complexion a youthful glow? Download your FREE “Best Anti-Aging Skincare Routine” to get started (it features product recommendations + right application order):

Side Effects Of AHAs

AHAs, especially glycolic acid, can irritate skin and even make it peel at first. That’s why it’s best to start with a small dose (around 5%) a couple of times a week and build up dose and frequency from there slowly. Also, if you exfoliate in the morning, apply sunscreen afterwards. Like all forms of exfoliation, AHAs increase skin’s sensitivity to UV rays.

What Are The Best AHAs Exfoliants?

  • Paula’s Choice Advanced Smoothing Treatment 10% AHA ($39.00): This super-concentrated exfoliating cocktail contains Glycolic, Lactic, Malic, and Salicylic Acids to smoothen out imperfections, fade away dark spots, and treat acne. Available at Cult Beauty, Dermstore, Paula’s Choice, Selfridges, and SpaceNK.
  • The Ordinary Glycolic Acid 7% Toning Solution: A simple, no-frills Glycolic Acid exfoliant that brightens the complexion and fades away dark spots. Available at Beauty Bay, Boots, Cult Beauty, Sephora, SpaceNK, The Ordinary, and Ulta.
  • The Ordinary Lactic Acid 10% + HA 2% ($8.90): A simple Lactic Acid exfoliant enriched with Hyaluronic Acid to exfoliate and hydrate skin at the same time. Available at Beauty Bay, Boots, Cult Beauty, Sephora, SpaceNK, The Ordinary, and Ulta.
  • The Ordinary Mandelic Acid 10% + HA ($6.80): A basic formula with mandelic acid to exfoliate oily-acne prone skin and Hyaluronic Acid to hydrate. Available at Beauty Bay and Ulta.

Related post: Glycolic Acid VS Lactic Acid: Which One Should You Use?

the ordinary salicylic acid 2 solution

What IS BHA?

BHA stands for Beta Hydroxy Acid. There’s more than one but I use the singular here, because they’re only one form of BHA used in skincare products. I’m talking about salicylic acid. It’s derived from willow tree bark. Although AHAs and BHA are very similar, they differ in their position of the one hydroxyl group. If that’s too scientific for you, know this: Salicylic Acid is oil-soluble. Unlike AHAs, it can penetrate through the skin’s lipid barrier and get inside your pores.

The Benefits Of BHA

Salicylic Acid exfoliates skin the same way AHAs do: they dissolve the glue that holds skin cells together so they can slough and reveal the brighter and smoother skin underneath. This exfoliating action also prevent dead cells from getting stuck in your pores and causing acne and blackheads. But why should you choose it over AHAs then?

Unlike AHAs, BHA is oil-soluble, which means it can treat acne. Here’s how: BHA penetrates deep inside the pores. Once there, it exfoliates them from within, getting rid of blackheads, whiteheads, and pimples. While other exfoliants can only get rid of the head of the blackhead, for example, BHA gets rid of the tail inside your pores. Clean pores = no breakouts. One last thing: Salicylic Acid has anti-inflammatory properties that reduce the redness and irritation that always come along with pimples.

Who Should Use BHA?

Both AHAs and BHA exfoliate skin. The main difference is that AHAs are water-soluble while BHA is oil-soluble. So, only BHA can penetrate and unclog pores.

This makes it a better choice for:

  • Oily skin
  • Acne-prone skin
  • Anyone who wants to get rid of blackheads and whiteheads

If you’re dealing with any of the above, BHA is your ONLY option. You could try other exfoliants, but you’re wasting your money and time. They don’t work as well. Period.

Side Effects Of BHA

Salicylic acid is effective at lower concentrations than AHAs (1% or 2% work a treat). So, it’s less likely to cause irritations. But, it CAN still irritate your skin if you use it too often. Don’t go overboard! And, of course, it increases skin’s sensitivity to UV rays during the day, so don’t skip your sunscreen!

What Are The Best BHA Exfoliants?

  • Drunk Elephant T.L.C. Framboos Glycolic Night Serum ($90.00): Don’t let the name fool you. This exfoliant has both salicylic acid to unclog pores and glycolic acid to fade away the dark spots pimples sometimes leave behind. Available at Cult Beauty, Sephora and SpaceNK.
  • Paula’s Choice Skin Perfecting 2% BHA Liquid ($29.00): The cult exfoliant from the brand, it unlclogs pores and treats blackheads and acne. The texture’s a little sticky, but if you can take that, this is one of the best salicylic acid exfoliants out there. Available at Cult Beauty, Dermstore, Net-A-Porter, Paula’s Choice, Sephora, and SpaceNK.
  • The Inkey List Beta Hydroxy Acid (£9.99): A simple, no-frills salicylic acid exfoliant for people on a budget. Available at Cult Beauty and Sephora.

AHAs VS BHA: How To Choose The Right One For Your Skin Type And Needs

Are you confused about whether to use AHAs or BHA to exfoliate your skin? Which one to choose depends on your skin type and concerns.

If you have oily skin or any type of acne, including blackheads, go with Salicylic Acid. It’s the only exfoliant that can get rid of them.

If your skin is dry but you have blackheads on your nose you want to remove, BHA is still your best bet.

If you have dry skin or want to fade away dark spots, AHAs are your best bet. Lactic acid if your skin is sensitive, Glycolic Acid for everyone else.

Is your skin dry and has acne? Go with salicylic acid.

Do you want to fade away dark spots but your skin is acne-prone? Again, salicylic acid. It doesn’t work as well for dark spots, but you can always use a skin-lightning treatment, like azelaic acid or arbutin, to fade away dark spots.

In other words, if you have pimples, blackheads, or whiteheads, go with Salicylic acid no matter what your skin type is or what other concerns you have. For everyone else, AHAs will work better.

How To Use AHAs and BHA

You use AHAs and BHA in the same way: you apply them right after cleansing, as close to clean skin as possible, every other night. Too much exfoliation is bad for skin. When you remove too many cells and expose the raw skin underneath, your skin gets all red and irritated. Plus, it hurts. A. Lot. Do your skin a favour and exfoliate in moderation. This is especially important if you use other actives, like retinol. Using them on the same night is a no-no. Exfoliate one night, use retinol the next.

The only exception? If your skin is sensitive, use lactic acid no more than twice a week. Your skin is too delicate for frequent exfoliation. Twice a week is more than enough to keep skin radiant and smooth while avoiding irritation.

Can You Use AHAs and BHA Together?

As often in skincare, the answer is an annoying “it depends”. Both AHAs and BHA are exfoliant and your skin doesn’t need multiple exfoliants. One is enough. The more exfoliants you use, the higher the chances you’ll dry out and irritate your skin. I’ve seen this happening more and more since brands started releasing single acid products and people wanted to use all of them for different concerns. Don’t.

If you’re dealing with multiple skin concerns, like acne and dryness, or blackheads and dark spots, pick the one that addresses your main concern. For acne, that’s BHA. For dryness or dark spots, AHAs. Said that, if you want to use both acids, opt for a product that contains both of them, like Drunk Elephant T.L.C. Framboos Glycolic Night Serum. Why? Single exfoliants are formulated to be as powerful as possible. When you use them on the same day or alternate exfoliants every day, your skin gets too much exfoliation. When you use skincare products that combine them already, you only get the right amount of exfoliation you need (unless you overuse them, of course).

AHAs VS BHA: The Verdict

Both AHAs and BHA exfoliate skin. But AHAs are hydrating and collagen-boosting, which makes them ideal for dry and sun-damaged skin. BHA, instead, unclogs pores, making it a must for oily and/or acne-prone skin.

About Gio

Hi, I'm Gio. I'm a no-nonsense, tell-it-like-it-is skin coach and writer on a mission to help you achieve your best skin day ever - every day. I bust skincare myths and debunk marketing jargon to help you figure out what's worth the splurge and what's best left on the shelf - using science, not hype. I also offer skincare consultations to help you create the best skincare routine for your unique needs.