We’re holding out hope that some cosmetic chemist in some lab out there will soon have her eureka moment on this front, but in the interim,we rely on product cocktailing to get us by. We use serum A to address our hyperpigmentation, followed by lotion B to address the moisture loss, then layer treatment C on top to dissolve those dead skin cells and prevent breakouts. A very involved, time-consuming process, but it’s the only way to keep our skin in check at home.
Here, Rouleau gives us the scoop on which ingredients don’t play nice. Budding skin-care cocktailers should take heed — a few of these we had an idea probably weren’t a good idea to combine, but there’s one really surprising one in there almost all of us did regularly. Whoops again.
Retinol & Benzoyl Peroxide
This one seems like a bit of a no-brainer — two harsh products equal a one-way ticket to Red-And-Flaky Town — but what desperate woman hasn’t tried piling her anti-aging cream on top of her breakout treatment?
“Retinol, in its attempt to stimulate cell renewal (and reduce acne) from within, can cause the skin to feel sensitized,” says Rouleau. “And, benzoyl peroxide, while beneficial for drying up blemishes, can make the skin get dried out and even peel. The combination can inflame and irritate the skin, which is not what you want from your at-home products.” The better option? Rouleau says to treat this complexion conundrum with an in-spa peel done by a trusted aesthetician.
Sunscreen & Foundation
Okay, we are not only guilty of doing this, but we’re guilty of telling all of our friends and everyone in listening distance to do this, too. When you find a foundation you love, but it doesn’t have SPF, it just seems like the natural thing to do. Rouleau says while our hearts are in the right place, this is actually not the best way to protect our skin.
“It’s best never to mix your sunscreen and foundation makeup (or your moisturizer) together, because then you are not getting the full SPF number listed on the bottle,” she says. “A sunscreen is a drug that has been tested and approved by the FDA in its final form. Changing the formula by adding moisturizer or foundation makeup will alter a drug, so you can’t be 100% sure that it’s going to protect you.”
Not the end of the world, by any means, but if you’re someone prone to sun damage or skin cancer, you need to be sure your products are working at their highest efficacy. In those cases, Rouleau says to purchase a foundation or moisturizer with built-in SPF, so you can be sure you’re getting the optimum sun protection for your skin.
Retinoids & Glycolic Acid
Prescription retinoids, like Retin-A, and glycolic acid are both proven anti-aging superstars, but in this case two is not better than one. “While prescription retinoids can be more effective for resurfacing sun-damaged skin, they are even more irritating to the skin than non-prescription retinol,” explains Rouleau.
Because of this, dryness and peeling is common, until your skin gets used to it. NBD, right? Wrong: Rouleau says that when this dryness occurs, it causes causes tiny, superficial cracks in the skin — also known as a damaged protective barrier — and these invisible cracks in the skin allow moisture to escape more easily and irritants to get into the skin more readily.
“Since an AHA like glycolic acid has a lower pH than the skin has (which is how it dissolves dry cells on the surface of the skin), this damaged protective barrier can be exacerbated when using at the same time as a prescription retinoid,” says Rouleau. “The result can potentially cause a slight burn to the skin, similar to that of a chemical peel.” Her advice: You can still use them both, just use them on different evenings.
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Cleansing Oils & Treatment Serums
We’re big fans of cleansing oils for removing dirt, makeup, and oil without stripping or drying out the skin. And, while Rouleau says they are great, turns out they could be canceling out all the treatment products you use afterwards.
“These oils, while they feel luxurious to use and leave dry skin types feeling very soft, can leave a residue and barrier on the skin,” says Rouleau. “If you apply a treatment serum afterwards — with ingredients like beta-glucan, peptides, or vitamin C — it will prevent these active ingredients from getting deep within the skin where they need to go to provide skin correction.” And, since you’re usually paying more for serums because of the potency of the ingredients, Rouleau says you’re basically flushing your money down the drain.
The solution: Use cleansing oils in either the morning or the evening — whichever time of the day you don’t use a treatment serum.
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