Attention sensitive skin types: Mandelic acid may be the exfoliating AHA for you

While the skincare community has (rightfully) sung the praises of some of the most well-known chemical exfoliants on the market — like glycolic acid — for years, the downside to these powerful and effective acids is that they are often too harsh to use on ultra-sensitive skin or on a regular basis. This goes for even the most resilient, non-reactive skin types out there.

So what's an exfoliating fanatic to do? According to the pros, the answer is mandelic acid, the gentle alpha-hydroxy acid (AHA) that's derived from bitter almonds. It's mild enough to use often, but powerful enough to deliver results in a gradual and non-irritating way — great news if you're trying to treat discoloration (like melasma or other hyperpigmentation) without worrying about your skin freaking out.

To get the scoop on how mandelic acid works and which skin types should be using it, we consulted Dr. Marnie Fisher, a dermatologist at Kingsway Dermatology in Toronto.

"In general, AHAs, including mandelic acid, break the tiny bonds and bridges found between mature, dead skin cells, which are called squames," says Dr. Fisher. (They're the ones lying on the surface of the epidermis.) AHAs are used for "exfoliating those flat, dehydrated cell bodies."

Like other popular AHAs, by "removing dead squames from the surface, [mandelic acid] also removes the pigment molecules inherently placed in those cells," says Dr. Fisher. "When the epidermis undergoes a more rapid exfoliative process [than skin's natural exfoliative process], metabolism speeds up. The new cells are made more rapidly, and they will have less pigment placed in them."

But if all alpha-hydroxy acids essentially do the same thing, why go with mandelic acid, rather than the more commonly found glycolic acid, for instance? "Mandelic acid is slightly larger in size and [molecular] weight than other AHAs, namely glycolic acid," says Dr. Fisher. "It will penetrate the upper stratum corneum, also known as the group of dead skin squames, more gradually."

This means that mandelic acid is less likely to produce "symptoms like stinging, itching and warmth," she explains. It's "useful for all skin stages: young, old, sun-damaged, acne-prone..." says Dr. Fisher, but especially for those of us with sensitive skin, including conditions like eczema and rosacea, and darker skin tones, as its gentle nature makes it less likely to cause post-inflammatory hyperpigmentation. (Don't forget to wear sunscreen especially when using any AHAs, since they can increase skin's sensitivity to UV light and lead to deeper damage.)

Interested in trying it out? Dr. Fisher says that when you're shopping for skincare containing mandelic acid, you'll most often come across 10 per cent concentrations of the chemical. She advises that you look for a product with no added fragrances that could be potential irritants. And if you're concerned about the fact that it's derived from bitter almonds, perhaps due to a tree nut allergy, there's no need to fret. "Yes, this chemical can be found in nature," explains Dr. Fisher, "but [it] is synthesized through a variety of controlled chemical reactions to reach the end product of the AHA, which would not contain any nut protein residue." Of course, when introducing any new ingredient to your skincare routine, it's always a good idea to test it on a small patch of skin first.  

Below are some products that utilize mandelic acid.

This serum mixes mandelic acid with a gentle polyhydroxy acid, and is formulated to mattify skin and keep excess oil at bay. It can be worn both under or over makeup.

Neostrata Mandelic Mattifying Serum, approx. $38, Shoppers Drug Mart

The Ordinary explains the strength of its 10 per cent mandelic acid formulation by saying that anything higher "would simply be achieving an indirect peeling strength that is more easily offered through lower percentages of glycolic acid."

The Ordinary Mandelic Acid 10% + HA, $6.70, The Ordinary

These cult favourite, two-step pads are pre-soaked in mandelic and similarly mild lactic acid, and provide at-home skin exfoliation that won't irritate sensitive skin.

Dr. Dennis Gross Skincare Alpha Beta Ultra Gentle Daily Peel for Sensitive Skin, $115, Sephora

Souzan Michael is a Toronto-based writer and editor with a deep, undying love of astrology, watermelon and golden retrievers. Follow her on Instagram @suziemichael_.