9 skincare ingredient pairings you should completely avoid 

Some things are just meant to be together. We could list some, but let your imagination wander. Other things are better suited on their own—especially when it comes to certain skincare products. Powerful ingredients such as retinol, Vitamin C, benzoyl peroxide, and even certain acids demand to be the star of the show. Sharing the stage could lead to major drama in the form of irritation, redness, temporary staining, or just a general lack of desired results. "There are so many great active ingredients out there and it may seem like using more of them would give you better results, but that’s not always the case," says Aegean Chan, a board-certified dermatologist based in Santa Barbara, California. 

Unsure if you're giving your favourite serums and creams the spotlight they need? Well, we asked Chan and many other board-certified dermatologists to share which skin-care ingredients you should not mix together—*ever—*as well as alternatives they recommend. 

1)Retinol and Vitamin C 

These efficacious ingredients may brighten your complexion and fade dark spots better than anything else, but in tandem, they will not double your glow. If anything, your face will be left extremely uncomfortable. Both of the actives have the potential to irritate your skin, Chan says. 

Minimise redness and flaking by keeping your favourite retinol and vitamin C serums separate. Slot vitamin C into your AM routine, especially since it functions better in the daytime, she adds. (We have a handy list of our favourite serums spiked with the stuff if you're in the market for a new one.) Retinol is best for your PM skincare lineup, "as light can increase the degradation of the product," Chan explains. 

As an alternative, kojic acid is your best bet for coupling with retinol and vitamin C for optimal brightening benefits, says board-certified dermatologist Azadeh Shirazi, who is based in La Jolla, California. The sake byproduct works wonders with daytime and nighttime routines to decrease the appearance of hyperpigmentation, especially with the serum below. 

2. Vitamin C and alpha hydroxy acids (AHAs)

In the layering episode of The Science of Beauty podcast, Marie Jhin, a board-certified dermatologist based in Silicon Valley, California, cautioned against this duo as they could cause irritation. Consider the same advice as above: Vitamin C in the morning; AHAs in at night. 

3. Vitamin C and benzoyl peroxide

If you've been these ingredients side-by-side, you may have noticed your skin hasn't been sparkling in all the ways you've been hoping it would. Well, there's an explanation for that: benzoyl peroxide cancels out the magical benefits of Vitamin C by degrading, or oxidising, it. 

4. Retinol and benzoyl peroxide 

Although both of these potent ingredients are effective acne-fighting ingredients, you should never combine them. Reason being: benzoyl peroxide can oxidise and degrade tretinoin, Chan notes. "The two ingredients together neutralise each other, making each less effective and may increase the chance of irritation when layered," adds Chicago-based dermatologist Caroline Robinson.

Instead, Robinson and Chan recommend relegating benzoyl peroxide to your morning routine and retinol to your nighttime one. Neutrogena's Stubborn Acne + Marks line makes this easy to remember. 

Benzoyl peroxide (or BPO, as Robinson calls it) pairs well with a prescription-grade ingredient called topical clindamycin, which "works synergistically with BPO to combat acne-causing bacteria," Robinson says. Retinol, on the other hand, is better suited with hydrating glycerin, hyaluronic acid, and niacinamide-based formulas, she adds. 

5. Retinol and AHAs

Another recipe for major irritation is retinol mixed with alpha hydroxy acids, like glycolic, lactic, and citric. "Both of these ingredients disrupt the skin barrier," Chan explains. If you double team your complexion with them, excessive dryness, redness, sensitivity, or a rash are very possible results. 

Instead, alternate the days you throw them on. One or two times a week, Chan reaches for an AHA with a 10 to 20 per cent concentration. On the other days—and if her skin isn't acting up—retinol is put into action. 

6. Retinol and salicylic acid 

Another acid and retinol marriage that should be avoided includes that of the beta hydroxy acids (BHA) variety. Salicylic acid, in particular, is way too drying and irritating for your skin to withstand, Shirazi says. 

Shirazi also suggests niacinamide as a substitution for both salicylic acid and retinol because it has anti-inflammatory properties to help calm skin. With salicylic acid, niacinamide effectively banishes breakouts by regulating oil production, reducing clogged pores, and exfoliating the skin, she says. 

Collagen peptides, which increase skin elasticity and firmness, are another good option in place of salicylic acid as retinol enhances their penetration. "Combining these ingredients doesn't lead to irritation or over-exfoliation, keeping the skin barrier healthy," Shirazi explains. 

7. Dapsone, aka aczone, and benzoyl peroxide

You know how they say if you eat too many carrots, you'll start looking like one? Well, smoothing on topical dapsone and benzoyl peroxide simultaneously can cause your skin to have the same kind of orange discolouration without consuming a single carrot, according to Chan. Stick to only one of the acne-treating ingredients at a time to maintain to your true colours. Also, remember salicylic acid and benzoyl peroxide are always a viable pairing. 

8. Benzoyl peroxide and hydroquinone 

One of the crucial tips dermatologists share with their patients they prescribe hydroquinone to is avoid merging it with benzoyl peroxide in your skin-care routine. Together, they can do the exact opposite of what you want them to do and end up temporarily staining your skin. 

9. Hydroquinone and AHAs

Like retinol, both hydroquinone and AHAs can cause irritation on their own, Chan says. You might as well skirt the issue as much as you can by separating them among your morning and nighttime routines or seeking out a hydroquinone replacement, like tranexamic acid, liquorice extract, or vitamin C. We're loving the Eadem Milk Marvel Dark Spot Serum as an alternative. 

Overall, Chan advocates for using any potentially irritating ingredient on its own for at least a few weeks. "If a certain ingredient leads to skin irritation on its own, you should definitely not use it with other potentially irritating ingredients," she explains. "Even a ubiquitous ingredient like niacinamide can potentially irritate skin." 

Also, giving your skin breaks from actives is incredibly important, Chan adds. If you're noticing irritation or dryness, be sure to seek advice from a board-certified dermatologist and try a gentle cleanser and thick moisturiser in the meantime. 

This article was originally featured on Allure.com

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