Alpha hydroxy acids (AHAs): what they are & how to use them in your skincare routine
Amelia Jean Hershman-Jones
Beauty & skincare
Reading time: 8 minutes
We break down everything you need to know about some of the most popular exfoliating ingredients in skincare today
You may think you know your glycolic acid from your salicylic acid, but even if you’ve incorporated acid into your skincare routine, the difference between them can be difficult to get your head – and face – around. But not anymore, thanks to our guide on alpha hydroxy acids (AHAs), from the skin-loving benefits right down to the not-so-loving potential side effects.
What are alpha hydroxy acids?
“AHAs are a group of plant and animal-derived acids used in a range of skincare products,” says Claire Williams, skin expert and founder of the WOW Facial.
The water-soluble chemical exfoliants can be either naturally occurring or synthetic and many are derived from organic sugars – glycolic acid is from sugar cane, lactic acid is from milk, malic acid is derived from apples and mandelic acid is from almonds.
What are the benefits of using AHAs?
“AHAs have been used in skincare products for quite some time, and their use has only increased with the wealth in research surrounding their benefits for skin,” says Claire.
Glycolic and lactic acids tend to be the most commonly used AHAs in cosmetic products. Their main benefits include helping to reduce visible sun damage, smoothing the appearance of fine lines and encouraging hydration[1].
"But they can also help get rid of layers of dead skin cells, promote radiance, reduce dry skin and smooth," says Claire.
Essentially: they help skin peel away the surface so that new, softer and more evenly pigmented skin cells may generate and take their place.
How should you use AHAs effectively & safely?
“The trick to introducing AHAs is to take it slow and use a lower percentage acid a few times per week to see how your skin reacts to it,” explains Claire. Look for ones that contain a concentration of around 5% as a rough guide. If your skin’s particularly sensitive, you may want to try using them once a week at first, before gradually building up your tolerance as overuse may lead to irritation. You may also want to consider trying gentler AHAs, such as lactic acid or mandelic acid.
“If you're new to acid products, try using pre-soaked toner pads before going freehand,” suggests Claire.
However, it’s worth noting that AHAs can increase sun sensitivity, so it’s important to incorporate a daily sunscreen into your routine. Check out our edit of the best everyday facial SPFs to find your perfect match.
Which ingredients shouldn’t AHAs be used alongside?
“Retinol combined with these acids is a recipe for disaster,” says Claire “They can leave your skin dry and irritated.”
“The main job of AHAs is to exfoliate, which retinol already effectively does. It’s better to mix AHAs with moisturising ingredients and SPF.”
Who should use AHAs & who should avoid them?
“AHAs may be more appropriate for age-related skin concerns, such as fine lines and wrinkles, but can be irritating for those with inflammatory conditions, sensitive or sensitised skin,” explains Claire. One study[2] revealed that, of the AHAs, lactic acid is less likely to cause irritation.
“Just be sure to incorporate products gradually to reduce irritation,” adds Claire. And choose lower percentage concentrations where you can – particularly if you’re an AHA newbie.
Can AHAs be used in bodycare?
“Yes,” says Dr Usman Qureshi, an aesthetic doctor and founder of the Luxe Skin clinic. “Use an AHA body exfoliant that contains glycolic or lactic acid to help improve the look of dry skin that’s crêpey or sun damaged.” To help reduce your risk of irritation, start slow and build up use gradually.
How can I reduce possible side effects when introducing AHAs into my skincare routine?
“I recommend applying your AHA at night,” explains Dr Qureshi. “Apply your AHA exfoliant after the cleanser and toner steps in your routine. If it’s a liquid, apply it with a cotton pad, if a lotion or gel, apply it with your fingers.”
And how often you should exfoliate so that you reap the benefits but not the possible side effects, depends on your skin type and skin concerns. “Some people do well exfoliating with AHA twice a day, whereas others find that once a day or every other day is a perfect balance. Test – starting gradually – to see what works best for your skin,” says Dr Qureshi.
Which ingredients pair well with AHAs?
“AHAs can be mixed with moisturising ingredients, such as ceramides, and rosehip oil to get effective results,” says Dr Qureshi.
They also play well with niacinamide if brightening is your goal, as well as for “fading pigmentation and reducing the appearance of wrinkles”, says Dr Qureshi. “It is possible to find a few acid products containing low doses of niacinamide, but using two different products will provide more beneficial properties.”
For an ideal combination, Dr Qureshi recommends AHAs plus hyaluronic acid. “Hyaluronic acid doesn’t function like an AHA – it doesn’t strip skin, but is highly nourishing and hydrating, so having “acid” in the name is a bit misleading,” he says.
Keen to try an AHA alongside another product? We’ve broken down the dos and don’ts of layering to get the most bang for your skincare buck.
Are AHAs best used in rinse-off or non-rinse products?
Both. The longer the product stays on the skin, the larger the impact, but sensitive skin may be more suited to the gentler touch of wash-off cleansers or face masks.
“AHAs are usually included in leave-on products, such as serums, toners and creams, as well as concentrated treatments via chemical peels – and are most effective that way,” says Dr Qureshi.
Our pick of the best alpha hydroxy acid products
From exfoliating serums and toners to face and body creams, we’ve got all your top-to-toe needs covered.
For more inspiration, have a browse of our full range of skin-smoothing products.
Try: Ole Henriksen Glow2OH Dark Spot Toner
• Size: 190ml
Formulated with glycolic acid, this skincare powerhouse targets hyperpigmentation and dark spots. When swept over your face post-cleanse, skin appears brighter and smoother, and is perfectly primed for the next steps in your skincare regimen.
Try: Fenty Skin Pre-Show Glow Instant Retexturizing 10% AHA Treatment + Reusable Applicator
• Size: 30ml
Rihanna has unleashed the secret behind her glowing skin – and it begins with 10% AHAs, including glycolic, citric and lactic acid. This gentle, yet effective trifecta, helps reduce the appearance of pores and fade dark spots, and boosts skin’s moisture content. Simply work over the face using the handy applicator included for 60 seconds, then rinse for brighter-looking skin.
Try: Drunk Elephant T.L.C. Framboos Glycolic Night Serum
• Size: 30ml
• Fragrance-free
• Cruelty-free
This AHA/BHA hybrid gel acts as the perfect pick-me-up for dull, congested skin. Helping refine skin texture and lift away dead skin cells, it adds luminosity and clarity to a lacklustre complexion.
