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Alpha Hydroxy Acids: A guide to AHAs

Types of AHAs, where to find them and how they’ll transform your skin

Want to get your glow back? Alpha hydroxy acids (AHAs) are a class of naturally derived organic acids found in skincare products that primarily work as exfoliators, but avoid the need to physically scrub skin.

Discovered in 1974 by two dermatologists through their research on an inherited dry skin disorder, they work by effectively dissolving the bonds between skin cells and encouraging the top layer of dead cells to shed while also promoting their turnover.

While exfoliation is a key benefit of using AHAs in your skincare regime, these transformative cosmeceutical ingredients also tone, brighten, smooth, resurface and reverse the signs of age and photodamage. If you haven’t yet tried AHAs, what are you waiting for?

What are the most popular AHAs?


  •  Glycolic acid: Want noticeable results? Glycolic acid, which is derived from sugar cane, is the smallest of the acids so has the ability to penetrate the skin effectively and deeply, and resurface the skin without scrubbing; it’s the active ingredient found in clinic peels.

  • Citric acid: Derived from citrus fruits such as lemons or limes, citric acid is used commercially to adjust the pH of a product to prevent it from being too alkaline. As an AHA it is also effective at exfoliating, improving elasticity and thickening skin in the right formula and concentration.

  • Lactic acid: According to Google data, lactic acid is one of 2020’s most searched for skincare ingredients. Derived from lactose, lactic acid is milder than glycolic acid and considered the silver bullet for hyperpigmentation and age spots. A gentle, non-friction type of exfoliant, it’s therefore ideal for sensitive and acne-prone skins. It also works to pull water into the skin, prevent congestion and improve pigmentation.

  • Malic acid: Another gentle acid, malic acid is derived from apples and pears, and can help to brighten skin by exfoliating the skin’s top layer and promoting cell turnover. With a larger molecule size than other AHA’s (meaning it cannot penetrate as deeply), it’s another good choice for sensitive skin and those prone to spots and acne.

  • Mandelic acid: The AHA of the moment and the one with the most growth potential, mandelic acid is derived from bitter almonds and is powerful but gentle, so reduces the risk of irritation or redness. Loved by acne sufferers as well as those with pigmentation and fragile skin, its’ molecule size is twice as big as glycolic acid. It’s used to remove dead skin cells, strengthen collagen, brighten and give it a healthy glow, and is also the acid of choice for darker skin.

What will AHAs do for my skin?

While beneficial for most skin types, AHAs are ideal for giving skin a fresh and healthy glow, improving the appearance of sun damage or uneven texture, and helping to clear pores making them suitable for treating acne.

Those with skin on the sensitive side will benefit from the chemical (as opposed to physical) exfoliation, but may want to choose formulas that include an amino acid or peptide which works to slow their penetration into the skin, or opt for the gentler AHAs listed above.

AHAs are not just effective for the face – if you are prone to spots or acne on your chest or back, glycolic acid-based body care products can help to promote cell turnover and slough off rough patches, while leaving skin smoother, fresher and more even-toned.

Key skincare benefits of AHAs

  • Fresher, clearer skin
  • Smoother skin with improved skin texture 
  • A stronger, thicker stratum corneum (the skin’s top layer)
  • Brighter, glowing skin
  • A reduction in hyperpigmentation 
  • A more even skin tone.

Which products and treatments contain AHAs?

Home use products usually contain lower concentrations of AHAs, typically around 4-16 per cent. Anything claiming to have a higher concentration is probably likely to be ‘buffered’ with an alkaline agent or other skin-stimulating ingredients.

Looking for something stronger? Chemical peels containing higher strength AHAs (up to 70 per cent) are available in-clinic to treat scarring and melasma (pigmentation) and resurface the skin.

But don’t worry about ending up with a red, raw face akin to Sex and the City’s Samantha (Google it if you don’t know what we’re talking about!) – professional peels are very safe and only performed under supervision by trained practitioners or dermatologists.

AHAs can be found in the following products:

  • Cleansers A cleanser containing glycolic acid will exfoliate skin and as it’s not in contact with the skin for long, is a good starter product for those wishing to introduce AHAs into their regime. 
  • Toners Resurfacing toners can help brighten the skin – those containing lower strength AHAs should be tolerated by most skin types.
  • Serums Active leave-on serums can be used at night to even out the skin tone and transform its appearance, but introduce them into your regime cautiously at first as they work on a deeper level. 
  • Facial pads These exfoliate and brighten dull skin and come in degrees of strength.
  • Facial exfoliators AHAs excel in chemical exfoliation – this means they do not use harsh, physical exfoliants or scrubs, making them potentially less irritating and highly effective.
  • Face masks Brightening, smoothing and resurfacing, these should be used once a week as they are likely to be more active. 
  • Body lotions and washes Usually containing lactic or glycolic acid, these offer exfoliating benefits without scrubbing the skin, leaving it smooth, soft and glowing. 

Whichever product you opt for, skin specialists advise that the products’ pH should be low, in-between 3 and 4, to prevent redness and flakiness.


Are AHAs safe? Are there any side effects? 

It’s all about the concentration with AHAs – if your chosen acid is concentrated enough to penetrate the skin, you should feel a tingling sensation on application which is normal.

However, the aim is to achieve stimulation without upsetting the skin – any irritation can take a few days to surface, so take it slowly to start with; it’s wise to perform a patch test if you think your skin may react.

Mature or dry skins, and those with skin conditions such as rosacea or eczema should avoid using glycolic acid as it may be too irritating.

If using an AHA product or peel, it’s vital to use a high factor sunscreen (SPF) during the day as your skin may be more sensitive to UV light, due to the constant exfoliation your skin is undergoing.

In fact, a study concluded that continual use of AHAs can cause the skin to burn when exposed to UV light up to 24 hours after the last application.