Fast Guide for Exfoliating Acids – AHA vs. BHA vs. PHA vs. LHA

Everyone talks about acids (and chemical peels), but what do they actually do?
You have definitely heard of exfoliating acids, but when you have to choose one, the names suddenly turn into a list of confusing abbreviations: AHA, BHA, PHA, LHA.
You might think they all do the same thing, just with different strengths. In reality, each of them has its own personality – a different way of cleansing, brightening and balancing your skin.

If you have ever dreamed of clear, even skin with that natural, filter-free glow, it is time to understand who does what in the world of chemical exfoliants.

1. AHA – for glow and an even tone

AHA – Alpha Hydroxy Acids – are water-soluble acids (for example glycolic acid, lactic acid). They work on the surface of the skin, dissolving dead cells and encouraging cell turnover.

Who they are for: dry, dull skin, with pigmentation marks or post-acne marks.

Main benefits:

• brighten the complexion and even out skin tone;
• support cell renewal;
• smooth the skin’s texture.

Tip: Start with gentle formulas such as AHA 7 Whitehead Power Liquid by COSRX – ideal if you have sensitive skin and have never used acids before.

2. BHA – for clear pores and acne-prone skin

BHA – Beta Hydroxy Acids – are oil-soluble acids that travel deep into the pores, helping to dissolve sebum and impurities. Salicylic acid is the best-known member of this family.

Who they are for: combination or oily skin that is prone to acne and blackheads.

Main benefits:

• unclog pores and help prevent breakouts;
• help reduce inflammation;
• soothe irritated skin.

A study published in the Journal of Cosmetic Dermatology (2024) shows that AHA and BHA, used regularly, can improve skin texture and radiance in as little as four weeks. If you struggle with any of these concerns, you can try COSRX BHA Blackhead Power Liquid – a bestseller for clearer pores and a more even-looking complexion.

3. PHA – gentle exfoliation for sensitive skin

PHA – Polyhydroxy Acids – are the “gentler cousins” of AHAs. They exfoliate softly, hydrate and help support the skin barrier.

Who they are for: sensitive, reactive skin, with rosacea or a compromised barrier.

Main benefits:

• delicate exfoliation without stinging;
• improved hydration;
• support for the skin barrier.

My skin is very sensitive and prone to atopic dermatitis. It is quite hard to find something that does not make my face red or give me a burning sensation. I have tried quite a few combinations and serums, but I got on very well with the Pore Shooter Ampoule by Returnu. It has an oily-like texture, it did not dry out my skin, although it did leave a bit of shine. I would say it is perfect for introducing exfoliation into your daily routine.

4. LHA – next-generation exfoliation

LHA – Lipohydroxy Acids – are derivatives of salicylic acid with a slow, targeted action. They penetrate the skin gradually and offer controlled exfoliation.

Who they are for: mature, sensitive or acne-prone skin.

Main benefits:

• help reduce imperfections without added irritation;
• support cell renewal;
• give a soft, refined skin feel.

Until not long ago I did not even know what LHAs were – or that they existed at all. I came across them by chance while reading about AHAs, BHAs and PHAs, trying to work out what I should buy for my skin. The internet recommended LHAs because they are a bit gentler, acting mainly on the surface of the skin. I have not tried them yet, but they seem like mild, precise ingredients, often used in premium dermatocosmetic formulas. You can find some here.

How to combine them correctly

Now that we have covered what each one does, it is time for the tricky part: how to combine acids safely.

Think of acid combinations like a diet: balance, not excess.

Basic rules are quite simple:

• Do not use AHA and BHA on the same day – especially if you have just started learning about acids.
• The key is to alternate: Monday AHA, Wednesday BHA, Friday PHA.
• Always use SPF during the day (really – without it, all the effort is wasted).
• After exfoliation, moisturise well with something like Dr. Jart+ Cicapair Calming Gel Cream to soothe and support the skin barrier.

Keep in mind that daily application “for fast results” is not recommended and can easily lead to irritation. Your skin does not need speed, it needs consistency.

The right exfoliation makes a difference

Whether you want to manage acne, fade marks or simply bring back your natural glow, choosing the right acid is essential. Proper exfoliation is not about being harsh, it is about listening to your skin.

Start gently, build a routine that works for you (not just one that looks good on social media) and explore the products that can genuinely improve the way your skin looks and feels.

Discover our collection of exfoliants at 24skin.co.uk.