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Today we're talking one of my favourite skincare ingredient discoveries of the past year or so: PHAs! What are they? Why are they great? All that and more is coming your way...
PHAs are Polyhydroxy Acids, a class of ingredient that has two main varieties: gluconolactone (the most common) and lactobionic acid. These are next-generation exfoliating acids not entirely dissimilar to AHAs (lactic, glycolic, mandelic etc.) Whilst they have a larger molecular size than something like glycolic acid, they are still penetrating (otherwise they wouldn’t really be effective), just at a slower rate. A lot of the same warnings apply as with other acids. The other thing to note is that the pH of formulas containing PHAs usually isn't quite as low as with something like glycolic, so they can feel less harsh in that respect too.
The fact they can be less sensitising than something like glycolic acid is obviously a bonus, and the fact they work so effectively on the surface level of the skin makes them a good option for dry winter skin when you want to get a bit of mild exfoliation in. But they have the additional benefit of actually having a hydrating element to them. For this reason, they're a really nice choice for dry and mature skin types, and are probably the best option for sensitive skin that's been put off ingredients like glycolic. Just be sure to follow the usual exfoliation rules around sunscreen, patch-testing and phasing the product into your routine. It also doesn't have to be an either / or because PHAs can really compliment other exfoliating acids that work in a slightly different way or on a different level of the skin.
PHAs are often found in cleansers and these fine to use daily, but focusing in on leave-on products, up to 10% is an effective concentration for exfoliating the skin. You might see PHAs in low concentrations for their hydrating benefits or to increase the penetration of other active ingredients within a formula. I'd say that if you can use a leave-on glycolic acid at 5% 2-3 times a week, you could do a PHA leave-on product at 10% around 3-4 times a week, so don't go HAM just because PHAs are a little gentler, less stripping and more hydrating! They're still a chemical exfoliant. Personally, as I use ascorbic acid every morning and retinal every evening as a general rule, I don't rely so much on acids these days for glowing skin and speeding up skin cell turnover, so something like a PHA 3 times a week works perfectly for me most of the time.
the Inkey List's PHA Toner* | £9.99 | formulated with 3% gluconolactone, which is what makes it my top pick for sensitive skin. If you're very sensitive and your skin doesn't really tolerate acids well, try this once a week. We also have 3% niacinamide in here which is right in that therapeutic range so you can reap the benefits with a far lower chance of irritation than if you reach for their 10% serum. It both helps stop the spread of hyperpigmentation and also stimulates ceramide production in the skin, supporting the health of the lipid barrier. Then we have soothers, moisturisers and hydrators like glycerin, aloe and castor oil, making this a great all-rounder.
The one I currently have on the go is the Medik8 Press & Glow Daily Exfoliating PHA Tonic with Enzyme Activator* | £25. As I've already outlined: I don't use this daily! I personally don't see the need to use any leave-on exfoliant every day and I like to be intentional with my skincare. What I like about this is that it's designed to work synergistically with something like the retinal from the same brand. This is definitely an advanced skincare tip, but throwing this in 3 times a week before your retinal can help with penetration, if you want to give things a little boost. There's 5.5% gluconolactone in here, which is again on the gentler side and it has a hydrating quality as well as smoothing the skin through exfoliation. It's formulated with aloe, glycerin and antioxidant botanicals.
There is a toner in this same line but I thought we'd switch it up for this post and add in a cleanser (both are reviewed here). The Scientia Pure Clarity Deep Clean PHA Cleanser* | £24 | sounds like it's going to be super foamy and stripping, but it's really not! It gently lathers but doesn't feel at all drying on my skin. This is great if you're more on the sensitive side and you're not wanting to jump right into a leave-on chemical exfoliant. Alongside gluconolactone, we have niacinamide (for it's clarifying and skin-barrier-boosting benefits), squalane (a skin-similar plant oil) and then hydrating, soothing aloe and rose water. Glycerin attracts water and green tea and Vitamin E act as antioxidants. There's so much great stuff in here and it definitely helps maintain soft, smooth skin over continued use.
A great example of how PHAs can be combined with other acids is the Glow Recipe Watermelon Glow PHA + BHA Pore-Tight Toner* | £31. This does contain fragrance, so if you're sensitive to that: give this a miss. If not, I really enjoy the hydrating, more weighty, almost essence-like texture with ingredients like cactus, watermelon, cucumber, glycerin and hyaluronic acid. It combined gluconolactone with some gentler alternatives to salicylic acid, which are oil-soluble, so the PHA is working on a surface-level and the BHA is working within your pores. It also contains licorice extract, to help with pigmentation. This is hydrating, smoothing and blemish-fighting all at once.
Next, we have our strongest option which is probably as far as I'd look to go with a PHA if you're considering it as a less-harsh option. The Indeed Labs Gluconolactone 10% Toner* | £14.99 | doesn't have a ton else going on (just be aware if you have sensitivities that there are some plant extracts in here, including citrus). However, it's a really effective formula; I definitely feel it on my skin a bit more than the other products in this post, but it's still gentle. I'd say this gives the most robust exfoliation, so I'd stick to 2-3 times a week on it and you'll still most likely see the skin-smoothing results you want.
Lastly, we have a serum, which is gentle softening and smoothing as well as being hydrating. The Equal RX Oat Milk PHA Serum | $28 | is something I can use most days, so let's peg it at 4 times a week with no other exfoliation if you're an advanced skincare user. This is a really interesting formula with 5% lactobionic acid (just to switch things up!) There's saponins in here as an anti-inflammatory with beta glucan as a hydrator. Also on the hydration front, we have a polysaccharide derived from snow mushroom and there are oat extracts in here for their soothing benefits. It has a milky, moisturising quality to it because of the shea butter and mango butter in here, despite it being a primarily water-based serum. Then we have Vitamin E for nourishment and to get some antioxidant goodness in there. Is it the most intensely-exfoliating product ever? No, but it's a fantastic all-rounder for more sensitive skin or even to slot into a routine that's heavy on other active ingredients.
Have you tried PHAs in your skincare routine?