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Beauty experts explain why putting acids on your skin is good for you

Everything you need to know about AHAs, BHAs and PHAs, and how you can use them to elevate your skincare routine.   

Beauty experts explain why putting acids on your skin is good for you

Using skincare products with acids in them can help speed up the skin’s natural exfoliating process, which results is a clearer, smoother and more even skin texture. (Photo: iStock/PeopleImages)

A little acid never hurt anyone, said no one. After all, the mere mention of the word “acid” conjures up images of painful chemical burns. But in actuality, our skin can benefit from the regular use of skin-renewing acids.

These acids help to remove the dead skin cells on the surface of the skin, which helps improve skin texture, said Dr Eileen Tan, dermatologist at Eileen Tan Skin Clinic & Associates.

Fact: Our skin’s natural pH sits between four and six on the scale, which is slightly acidic. It is also where the skin functions at its optimum.

When used in the right concentrations, skin-renewing acids are said to help fight acne, reduce the signs of ageing and give your complexion a glow. And while our skin does naturally renew itself every 28 days, this natural exfoliating process slows down with age and stress.

So sometimes a little help is necessary. Enter, acids in your skincare products.


Before we dive into how to incorporate skin-renewing acids into your daily skincare routine, it’s important to understand the difference between each, and how they work for your skin.  

The world of acids can be divided into three categories:


Alpha-Hydroxy Acids come from fruits, including lemons, oranges, apples and grapes, as well as milk, sugarcane and even almonds. (Photo: iStock/George Peters)

Part of a group of fruit acids, AHAs are useful in smoothening out fine lines, brightening skin and lightening pigmentation, said Dr Melvin Tan, medical director of Epion Clinic and Epion Aesthetics.

Common AHAs include lactic acid, mandelic acid, citric acid, phytic acid and glycolic acid; the latter is deemed the most potent of the lot. In fact, a 2003 study in the Journal of Experimental Dermatology found that glycolic and lactic acids can help regulate melanin production in skin.

While AHAs are generally well-tolerated by most skin types, Dr Eileen Tan recommends that those with drier skin use lactic acid.

A 1999 study in the Journal of Investigative Dermatology found that it increases the skin’s production of ceramides, a natural substance that locks moisture into your skin, thereby improving its hydration levels and strengthening the skin barrier.

According to, without this protective barrier, the water in your body would escape, causing dehydration. The skin barrier also prevents harmful substances such as germs and toxins from entering the body.  

Dr Eileen Tan added that those with sensitive or acne-prone skin might want to opt for mandelic acid as it has an anti-inflammatory effect.


Unlike AHAs, which are water-soluble, BHAs are oil-soluble. According to Dr Coni Liu, dermatologist at DS Skin & Wellness Clinic, this allows them “to get below the oil clog on the skin”, ideal for oily skins and in treating acne.

According to Paula Begeon, founder of Paula’s Choice skincare, the anti-inflammatory and anti-bacterial properties of BHAs can help soothe the skin and may even be used on skin that’s prone to redness.

The most common BHA is salicylic acid, along with derivatives of salicylic acid like lipohydroxy acid, salicylate, betaine salicylate and sodium salicylate. Other lesser known BHAs include willow bark extract, beta hydroxybutanoic acid and trethocanic acid.


Poly-Hydroxy acids are suitable for all skin types, including those with sensitive skin. (Photo: iStock/kitthanes)

While PHAs – gluconolactone, galactose, lactobionic acid and maltobionic acid – technically fall under the AHAs category, they’re suitable for all skin types, including sensitive skin.

AHAs are often associated with redness and irritation, thanks to their smaller molecule size, which allows them to be quickly absorbed into the skin. PHAs have a larger molecule size, so they not only penetrate less deeply into the skin, but are also slower to take effect, providing gentler exfoliation.

That’s why they’re ideal for sensitive or dry skin, and for those with skin conditions like eczema and rosacea, said Dr Melvin Tan.

In addition, PHAs are “strong antioxidants and humectants that can strongly attract and bind water”, said Dr Gladys Teo, head of research and development at Est.Lab, a home-grown skincare company that works with research institutions from all over the world.

This water-binding effect forms a hydra-film over the skin’s surface to help deliver moisture, softness and smoothness to the skin.


So why are acids important when it comes to skin renewal? And why should we bother with helping the skin exfoliation process along?

“Skin turnover is a continuous cycle of dead skin cells being pushed to the surface by new, healthy cells,” Dr Liu explained.

When these dead skin cells are compacted on the skin surface, they make the skin appear dull and lacklustre, she added. AHAs, BHAs and PHAs act like chemical exfoliants that break the bonds between dead skin cells, loosening them so they can be removed more easily.

Exfoliating your face with a physical scrub works only on the surface whereas skin-renewing acids go deeper into the skin. (Photo: iStock/Moyo Studio)

Doesn’t a facial scrub, with its tiny exfoliating beads, work just as well, you may ask.

These physical exfoliators work on the surface and don’t penetrate into the skin like chemical exfoliants do. The added bonus of acids is that they can help other skin issues too. For instance, BHAs help to clear out debris from clogged pores while AHAs are said to promote collagen production.   

“Chemical exfoliation serums offer a more physically gentle approach to skin renewal,” said Est.Lab’s Dr Teo.

But remember that as these are leave-on products, time is needed for the acids to work their way through the dead skin and pores, so you’ll need to use them diligently to see significant results. 

You can find skin-renewing acids in a wide array of products, from cleansers, toners, essences, serums and moisturisers, as well as body lotions and creams. Acid serums tend to be more popular as they can offer prolonged and more intensive care.

But if you’re acid-wary, start with toners containing AHAs, BHAs or PHAs which are milder compared to serums, said Dr Eileen Tan.


Dr Teo said hydroxy acids (AHAs, BHAs and PHAs) can be used alone or combined in many ways to treat different skin conditions and skin types.

In fact, it has been clinically proven that a mix of AHAs (lactic, glycolic and mandelic acids) and PHAs (gluconolactone and maltobionic acid) is effective in restoring dry skin to a normal, healthy state in two weeks.

In a 2009 clinical study in the Clinics in Dermatology Journal, it was discovered that a skincare regimen that included using a moisturiser with PHA and SPF15 in the day, combined with an AHA lotion at night, resulted in a significant reduction in hyperpigmentation and improved skin radiance in 12 weeks.

Furthermore, a 2020 clinical study in the Journal of Cosmetic Dermatology found that a formula of glycolic acid (an AHA) and salicylic acid (a BHA) delivered significant improvement in acne-related issues, including a more than 90 per cent decrease in blackheads and cystic acne.

AHAs, BHAs and PHAs combine well with other active ingredients like hyaluronic acid, retinol and antioxidants in your skincare routine. (Photo: iStock/Artfully79)

Skin-renewing acids play well with other common active ingredients. For instance, hyaluronic acid can alleviate and minimise any risk of skin irritation that might occur when using acids, said Dr Eileen Tan.

Antioxidants are also good companions to acids. She added: “Vitamin C can protect the skin from inflammation, reduce UV damage, minimise free radical damage and stimulate collagen synthesis, while ferulic acid can help achieve skin brightening and rejuvenating effects.”

Dr Melvin Tan, on the other hand, is a fan of combining AHAs with the anti-ageing favourite, retinol (including retin-A, which is applied as a topical cream prescribed by a doctor) to keep the skin blemish-free, smooth and youthful-looking.

For best results, he recommends using acids in the morning and retinol at night as the active ingredient makes the skin more sensitive to UV rays and also breaks down when exposed to sunlight, making it less effective.

Want an extra skin renewal boost? Use a milder exfoliating toner in the day and an acid-infused serum at night to achieve a “longer contact for skin repair and rejuvenation effects”, said Dr Eileen Tan.



  • This applies to both frequency of use and acid concentration.
  • For skincare acid newbies, start with one to two times a week, increasing its frequency as your skin gets attuned.
  • Concentration-wise, “opt for products with lower acid dosages of less than 3 per cent acid in total, using them not more than two times a week if you are just starting out,” said Dr Teo.


  • Stop using skin-renewing acids if skin feels overly tight, starts to peel, gets flushed or itchy. “There is such a thing as over-exfoliating, especially with the use of stronger AHAs such as glycolic and lactic acids”, said Dr Teo. “AHAs can benefit dry, aged and pigmented skin, but overusing them can result in extreme dryness and irritation.”
  • Switch to a gentler acid or formulation, or use a product with a lower acid concentration instead.


  • Dr Teo advised stopping for one to two weeks after completing a two- to three-week course of using high-strength AHA serums, or six to eight weeks of high-strength PHAs.


  • Acids can increase skin sensitivity, making it more susceptible to UV damage. So it’s crucial to apply sunscreen daily.


While acid serums aren’t new – they’ve been around since the 90s, there’s now an array of newer, more effective, and more importantly, skin-friendly ones available on the market. At the same time, you can tap on the skin-exfoliating power of acids in body lotions as well.

When using exfoliating body lotions, the same rules apply. Start slow – two to three times a week, and always use a sunscreen if you’re using your lotion or cream during the day, says Kamil Nowak, sales and education specialist at Drunk Elephant.

Have a look at what each of these skin-exfoliating products do:

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Source: CNA/pc