You really should be putting acids on your face

But not just any kind.
But not just any kind.
Image: Charles Sykes/Invision/AP
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For three years I was a beauty editor, and constantly experimenting with skincare products that breathlessly promised life-changing, time-reversing results. Today, when it comes to skincare, you might call me low-maintenance—or even lazy. But there’s a single, little-known step I still consider as important as cleansing, moisturizing, and sun protection. (That’s the bare minimum, people.) It comes right after the first, and you’re probably skipping it.

After my face is clean and dry, I dampen a cotton pad with a liquid that smells mildly of sour cabbage. I swipe it over my nose, cheeks, chin, forehead, and neck, repeating on oilier zones. This little daily effort has benefited me more than even the most expensive potions I’ve tried. The stinky stuff I swipe on my face is called Lotion P50, and it’s part of a family of skincare products that some call liquid exfoliants—although they couldn’t be further from the pulverized peach-pit scrubs we messed with in middle school. Others call them acid toners because, like toners, they are used right after cleansing. I don’t care what you call them; just start using them.

Here’s how they work

At their most basic level, these products loosen the bonds that hold dead surface skin cells together. The skin cells shed off imperceptibly, and reveal newer ones beneath, which are less damaged by environmental factors like sunlight and pollution. Over time, it diminishes lots of little things that make a big difference: dullness, congested pores, fine lines, and uneven skin tone.

What defines these products is the presence of acids: specifically either alpha-hydroxy acid (the most popular AHA is the sugarcane-derived glycolic acid) or beta-hydroxy acid (the BHA you may know is salicylic acid, which is chemically-related to aspirin and naturally occurs in willow bark). Both acids exfoliate skin and stimulate collagen growth, which makes the face look younger and plumper.

The cult of acid-users

What results is a fresh-faced, baby skin glow that inspires evangelism in those of us who’ve experienced it. Beyond putting up with the acrid smell, P50 requires customers in the US to register online before even looking at the $61 price tag. These are but tiny hurdles to joining the smooth-skinned cult of fashion editors and makeup artists who extol its virtues. One devotee compared her friend’s face to a fetus (in a nice way).

Lisa Airan, a New York City dermatologist, says that liquid exfoliants also make your skin more receptive to other products, allowing for better absorption. That’s part of why I chose a toner rather than one of the many cleansers, serums, moisturizers, or at-home peels that contain AHAs and BHAs. It frees up my cream and serum to deliver anti-ageing ingredients such as peptides, resulting in a potent and winning skincare cocktail.

Find your own

So how to choose a liquid exfoliant? AHAs help reduce pigmentation, fine lines, and acne scarring. BHAs are mildly antibacterial; they unclog pores and ease the reddening effects of rosacea.

Bryan Barron, co-author of The Original Beauty Bible and research director for the skincare line Paula’s Choice, says those with oilier skin or inflammation should go for BHAs. (He calls Paula’s Choice modestly priced Skin Perfecting 2% BHA Liquid the “gateway drug.”) When it comes to concentration, an AHA exfoliator should contain 5–10% alpha-hydroxy acid. A BHA exfoliator should have 1–4% beta-hydroxy acid. In both cases, says Barron, the product should have a low pH—ideally between three and four. Any higher, and you’ll miss out on exfoliating actions. Paula’s Choice makes it easy for neophytes by letting online shoppers browse by skin concern, such as blackheads or redness.

Beyond Paula’s Choice, and my chosen cult of P50, the glycolic acid-based Liquid Gold from the Australian skincare company Alpha-H has a fervent following among my peers. Model and beauty blogger Ruth Crilly swears by it, and Harper’s Bazaar singled it out as 2013’s “best skin brightener.” With its tingling effect, I can’t help but agree: It’s the best Aussie export since Hugh Jackman.

Proceed, cautiously

Once you choose your exfoliator, use it after cleansing at night. Start slow, about twice a week, building up to every alternate day or daily, depending on the product’s strength and your skin. Using one of these makes sunscreen an absolute necessity; and just make sure you don’t combine acids with products that contains retinol (major irritation potential) or vitamin C, which will be rendered ineffective. Make this part of your routine, and your face will thank you.