Beta-Hydroxy Acids (BHAs)

Penetrates the skin’s surface to break down dead skin cells, unclog pores and dry out excess oil.

Written by
Kate Evans
Medically reviewed by
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These days, we're all taking skincare much more seriously. In saying that, the rules seem more complex, the ingredient list harder to follow (or maybe we're just paying more attention to it), and it seems like you need a degree in chemistry to understand either the most complicated words out there, or the never-ending acronyms.

You've got AHAs, AzA. There are classics like SPF and pH. Some differ by a single letter or share their acronyms: LAA and LA (not the city).

And then you've got the one you'll learn about today — BHA. Or, by its spelled out version, beta hydroxy acid.

What is a beta hydroxy acid?

BHAs, or beta hydroxy acids, are a chemical type of hydroxy acid (as the name suggests) [1]. It's found in sweet birch bark, willow tree bark and wintergreen leaves [2], but can also be derived synthetically [1].

If you're wondering what makes beta hydroxy acid such a big deal (enough so that it gets its own acronym), it boasts a pretty unique characteristic — it's lipid-based [2]. Translation: it's oil soluble, so can permeate the skin through follicles, penetrate sebum and facilitate a deep cleansing of the pore.

If you've ever heard of or used, salicylic acid — then congratulations, you know a beta hydroxy acid. In fact, this is the "most often" used BHA in the cosmetic world [2].

Beta hydroxy acids vs alpha-hydroxy acids

Remember the AHA we mentioned in the intro? As it turns out, alpha hydroxy acid and beta hydroxy acid both belong to the category of hydroxy acids; they're the 2 main classes. AHAs and BHAs are some of the most widely used — and widely studied — anti-ageing skincare compounds [3].

Alpha hydroxy acids include glycolic acid, lactic acid and fruit acids; unlike beta hydroxy acids, they're water soluble — they're better for surface-level (literally) issues when it comes to your skin [4].

Both compounds have recognised exfoliation, skin texture smoothing and brightening properties; helping eliminate acne and improving your skin's appearance [5].

Another difference between the 2, other than solubility? AHAs are considered to have a great skin irritancy effect than BHAs, meaning they may cause discomfort to those with more sensitive skin [2].

Is beta hydroxy acid safe for the skin?

Yes, beta hydroxy acid is safe for the skin.

But — because there's always a but — sunscreen and other sun protection are strongly suggested if you use BHAs on your skin [2].

Why? It's an interesting, slightly oxymoronic one. Although the use of beta hydroxy acids appears to restore "unusual" damages caused by photoageing —a fancy word for sun damage — BHAs can also cause a 50% increase in sun sensitivity [6][2].

You see the conundrum. That's why it's recommended to use a sunscreen that offers UVA and UVB protection if your skincare routine incorporates BHA products — to prevent further sun damage [2].

Software's Daily Sun Defence sunscreen is formulated for the harsh Australian sun and provides both UVA and UVB protection. Plus, our sunscreen is fragrance-free, non-greasy and white-cast free and is non-comedogenic, so it won't clog your pores.

Studies have found that, in skincare products, BHAs work best in a concentration of 1-2%, at a pH level of 3-4 [3][2].

What are the benefits of BHAs?

What isn't a benefit of beta hydroxy acids, is the more accurate question? Yep, honestly, they're that good.

It helps with sun damage

As we've already touched upon, they're great for restoring issues caused by sun damage — including the alleviation of roughness, wrinkles and uneven pigmentation. This includes improving skin texture, skin tone and colour [7].

It improves your skin's surface

Beta hydroxy acid, in certain concentrations, can assist with a chemical peel. It's known for being a good peeling agent, in fact; BHAs have the ability to remove dead skin cells — specifically, salicylic acid helps with this [2][7].

It's oil soluble

This is one of the characteristics that makes BHAs so unique, as you already know. But because it can permeate the skin through follicles, it can aid in the exfoliation of your pores — in turn, decongesting deep-seated oil and debris [2].

So, if you're prone to oily skin, or combination skin that sees the production of excess oil at times, BHAs are "particularly beneficial" in the treatment of this [2]. In fact, we recommend our Salicylic Acid Foaming Wash if you have this type of skin, as it will help unclog debris and trapped oils in your pores.

It's good for acne

If you have acne-prone skin, sometimes it feels like it's a never-ending hand that you've been dealt with. But multiple sources recommend using a beta hydroxy acid for acne breakouts, mild acne, or as part of acne treatment.

BHAs have antibacterial and anti-inflammatory benefits; studies have found when salicylic acid is used in multiple sessions, it reduces the number of inflammatory acne lesions [8].

One double-blind, randomised trial looked at those with mild to moderate acne, with the active group using facial cleansing pads containing 0.5% salicylic acid twice a day for 12 weeks. Those in that group demonstrated a more significant reduction of both inflammatory lesions (red, swollen, painful blemishes) and open comedones (blackheads) [9][10][11].

Beta hydroxy acids help to "deep clean" the pilosebaceous unit, which is a key structure in the development of acne [1]. So really, you could help knock those acne breakouts on their head before they've even had the chance to flare up.

Other skin improvements

So along with everything else BHAs do, they can also increase skin thickness, improve skin barrier function, help prevent milia formation, shrink pore size, and improve skin elasticity. And, it's hydrating. It's the all-rounder of the skincare world [2][1][3].

Types of BHAs

In the US, the Federal Drug Authority (FDA, another acronym for you), says BHA ingredients can be listed as:

  • Salicylic acid
  • Beta hydroxy butanoic acid
  • Tropic acid
  • Trethocanic acid

Related substances to salicylic acid include salicylate, sodium salicylate, and willow extract [12].

Generally, you'll only ever see salicylic acid in relation to BHAs — it's the most common BHA. There are some acids that are considered to be both an AHA and BHA; these include citric acid and malic acid [13].

Who should use beta hydroxy acids?

If you're prone to excess oil — or, to be more specific, your skin is — or you have acne-prone skin (or breakout-prone skin), then beta hydroxy acids should definitely be up your skincare alley.

In fact, they're "fantastic" for these skin types; skincare products containing BHAs are also "especially beneficial" for those with sensitive skin or people of colour [2].

In addition to this, if you're someone who has spent a bit too much time in the sun (guilty, it can be part and parcel of our Aussie lives), and a sunburn (or 2) has taken its toll on your skin over time — then you, too, should incorporate BHA products into your skincare routine.

And last but not least — if you're someone who wants to keep your skin looking fresh and younger looking, then yes, you're now part of the BHA gang [2].

However, if you're trying to get pregnant or are currently pregnant, it's recommended not to use BHAs [14].

How to incorporate BHAs into your skincare routine

Okay, so before you start incorporating skincare products containing BHAs into your routine, you do want to do a patch test first.

No matter what concentration of beta hydroxy acid, test the product on a small area of skin before applying it to a larger area. If you experience skin irritation or prolonged stinging, stop using the product immediately, and consult your relevant healthcare provider [12].

Doctors actually recommend using salicylic acid as a cleanser — incorporated into the cleanser, that is, for gentle exfoliation — or as a treatment serum [15].

Our Salicylic Acid Foaming Wash is one of these cleansers and helps to gently exfoliate and slough away dead skin cells, as well as work to unclog pores and inject hydration into your skin.

Formulated for all skin types — including those of you reading this with sensitive skin — it's also great for acne-prone skin, and doubles as a spot treatment for your face, neck, chest and back.

Use in your evening routine, after a gentle cleanser but before your oils, moisturisers and balms. Pump and lather a small amount into your damp hands, gently massage onto the relevant areas and rinse thoroughly. A salicylic acid like this shouldn't be part of your everyday skincare routine, but it can be used up to 2-3 times a week.

If your skin looks flaky or irritated, this could be a sign your skin is drying out or the skin barrier might be damaged — so keep an eye out, just in case. Everybody's skin is different, and everyone's skin reacts differently.

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