Exfoliants 101: What are AHAs, BHAs, and PHA?

The world of skincare is riddled with exfoliants. AHAs, BHAs, and PHAs are the new buzzwords that can seemingly do everything for your skin. However, despite them all being exfoliants, they function a little differently. Here’s what they do for your face and which one you should pick for your skin -

Keynotes:

• AHAs, BHAs, and PHAs are exfoliating acids that improve skin texture and clarity by removing dead skin cells.
• AHAs work on the surface to brighten and smoothen skin, while BHAs penetrate pores to treat acne and oily skin. PHAs are gentler, making them ideal for sensitive skin types.
• Practice caution with exfoliants and start with low concentrations
• After exfoliating, always use day creams, night creams, and sunscreens to repair your skin barrier.

Alpha Hydroxy Acids (AHAs), Beta Hydroxy Acids (BHAs), and Polyhydroxy Acids (PHAs) are used in skincare for their exfoliating properties. As exfoliators, they help remove dead skin cells from the outer layer of the skin. This process promotes cellular turnover and improves overall skin texture and tone.

What are Alpha Hydroxy Acids? (AHAs)

Glycolic acid (GA), citric acid (CA), malic acid (MA), tartaric acid (TA), and lactic acid (LA) are all commonly used AHAs. These are naturally occurring organic acids present in many foods and milk sugars. They are water soluble and work on the skin’s surface to exfoliate it, while making it smoother and more radiant. AHAs have a small molecular size and can penetrate the skin to some extent. Research shows that the effectiveness of AHAs usually depends on their exposure time. For instance, compare an AHA cleanser to an AHA chemical peel. The latter may show better results due to longer exposure.

What are Beta Hydroxy Acids (BHAs)?

Salicylic acid, trethocanic acid, and tropic acid are some examples of BHAs. Salicylic acid is the most commonly used BHA and is extracted from plants like white willow and wintergreen leaves. BHAs and AHAs function in a similar way, except for the fact that BHAs are oil-soluble acids (primarily salicylic acid). This allows them to cut through the oils or sebum on your face and penetrate deep into the pores to unclog them, making BHAs ideal for acne-prone and oily skin. They also have an anti-inflammatory effect and have been proven to irritate the skin less when compared to AHAs.

What are Polyhydroxy Acids (PHAs)?

PHAs are often synthesized in labs but are naturally created by bacteria. PHAs function exactly like AHAs, except they have a larger molecular structure. This means that PHAs penetrate your skin more slowly and gently, making them suitable for those with very sensitive skin. Think of them as softer versions of AHAs. They are known for their anti-aging benefits. They work to hydrate your skin and boost skin cell regeneration to reduce the appearance of fine lines and wrinkles.

When it comes to hydroxy acid skincare, it’s crucial to select the right ingredient. Picking the wrong one may leave your skin more damaged than when you began. Now that you know what are AHA and BHA, and PHA, it’s time to assess their different benefits.

AHA in skincare - For Surface-Level Exfoliation

Unlike BHAs, AHAs are not oil-soluble and can only penetrate the skin up to a certain extent. If you are looking to remove dullness and dead skin cells from the upper layers of your skin, AHAs are for you. Some other benefits of AHAs are -

• AHAs like glycolic and lactic acid help remove the topmost layer of dead skin cells, resulting in smoother, brighter skin.
• AHAs like glycolic acid increase hyaluronic acid and collagen gene expression, preventing fine lines. This makes your skin appear plump and young.
• They help you fade any pigmentation on the surface of your skin by exfoliating the top layer.
• AHAs also improve your barrier function, increase epidermal proliferation and thickness, making your skin retain moisture and appear younger.
• Compared to PHAs, AHAs have a smaller molecular size and can give you deeper exfoliation.

BHA in skincare - For Deep Pore Cleansing

If you have an oily skin type and clogged pores, turn to BHAs. Salicylic acid, the most common BHA, is oil-soluble, allowing it to penetrate deep into the pores to reduce breakouts while also offering anti-inflammatory benefits. Some other benefits of BHAs are -

• BHAs can regulate excessive sebum. Cleansing gels with salicylic acid keep your pores from getting clogged and prevent whiteheads, blackheads, acne, and pimples.
• Lighter salicylic acid peels are useful to counter surface-level pigmentation like melasma, and stronger SA peels also help you tackle deep wrinkles and scarring.
• Salicylic acid also helps you reduce inflammation caused by acne. Lesser the inflammation, the lower the chances of skin damage and acne scars.
• Like AHAs, BHAs also have exfoliating properties that help you get rid of dead skin cells and reveal smoother skin.
• Salicylic acid is also an antibacterial ingredient that counteracts Cutibacterium acnes, a bacterium that can trigger acne outbreaks. This is why salicylic acid serums, like Eucerin’s DermoPurifyer Triple Effect Serum, are ideal for acne-prone skin.

PHAs in Skincare - Gentle Exfoliation for Sensitive Skin

PHAs like lactobionic acid and gluconolactone are ideal for people with sensitive skin. They have a large molecular size and can exfoliate your skin without irritating it or compromising its barrier.

• While being gentle, PHAs still manage to exfoliate dead and dull skin cells to reveal a brighter and fresher-looking skin tone.
• PHAs are also known to hydrate your skin, supporting its barrier function and locking in moisture.
• Exfoliation is tough when you’re fighting other skin concerns like rosacea or eczema. However, PHAs generally suit people with these skin conditions as well.
• PHAs also have antioxidant properties that can help you prevent any skin damage caused by UV rays.
• Like AHAs and BHAs, PHAs also support skin cell turnover and can brighten dry, sensitive skin while reducing fine lines.

While AHAs, BHAs, and PHAs can be used in multiple ways, via cleansers, toners, serums, creams, and even chemical peels, here are some things to remember before you start using them.

• Start with low concentrations. Consult your dermatologist and slowly introduce these skin actives into your regimen. Limit their use to 1-2 times per week.
• Use them early in your skincare regimen, before moisturising or using other actives. Salicylic acid cleansing gels or lactic acid toners can be a good start to your skin regimen, especially if you have oily skin.
• Always follow up exfoliants with a hydrating serum or moisturizer to maintain your skin barrier health.
• AHAs, BHAs, and PHAs can make your skin more sensitive to the sun. If you’re using them in high concentrations, it’s best to use them during PM routines and always wear SPF during the day.
• Avoid layering multiple exfoliants unless your dermatologist has asked you to do so.
• Avoid using strong retinoids, vitamin C, or other reactive acids at the same time unless advised by a skincare professional. Try gentle skin actives like Thiamidol instead.
• Always perform a patch test before incorporating a new acid into your routine.

When used correctly, hydroxy acids can significantly improve your skin’s texture, clarity, and overall health. AHAs, BHAs, and PHAs all offer different targeted benefits, from brightening dull skin, reducing acne to soothing sensitive skin. Understand your skin type and concerns to pick the one that suits you the best. Build up your AM and PM regimen with exfoliants and dermatologically tested skin care products by Eucerin.

1. Can I use AHA, BHA, and PHA together?

   While exfoliants can be mixed, it’s always best to consult your dermatologist, perform patch tests, and alternate their usage rather than apply them all at once. Going wrong with exfoliants can cost you your skin barrier health.

2. Which acid is best for acne-prone skin?

   BHAs like salicylic acid are the most effective for acne-prone skin due to their ability to penetrate oil and clear out clogged pores. They also reduce acne inflammation.

3. How often should I use exfoliating acids?

   As a beginner, start with 1-2 times per week and adjust your regimen based on your skin’s tolerance and product concentration. Over-exfoliation can damage the skin barrier.

4. Are AHA and BHA safe for sensitive skin?

   Compared to AHAs and BHAs, PHAs are the safest for sensitive skin. AHAs and BHAs can be used in lower concentrations, but a patch test and dermatologist consultation are advised.

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• Berson, D. S., Cohen, J. L., & Rendon, M. I. (2013). Current concepts in the use of superficial chemical peels. Journal of Drugs in Dermatology, 12(s1), s5–s10.
• Kubala, J. (2023, February 15). PHAs for your skin: The facts behind the beauty hype. Healthline.
• Pappas, A. (2018). Epidermal surface lipids. Molecules, 23(4), 863.