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With little else to do at the moment, some of us are turning to fastidious skincare routines for entertainment and we regret nothing. Supplements now form part of a regime that was once entirely topical. Our keratosis pilaris should be drastically reduced by spring. We’ve even gone so far as to address our issues with lip balms. But there is trouble in this productive (and pretty) paradise.

“Too many active ingredients in one product or combined in different washes, serums or creams can cause adverse effects to the skin”

Like several narcissists fighting for attention at a social event, some of the most effective skincare ingredients don’t like each other – at all. And the consequences can be disastrous. “Too many active ingredients in one product or combined in different washes, serums or creams can cause adverse effects to the skin,” explains Dr Barbara Kubicka, founder of Clinicbe®.

As deflating as this might be to discover, knowledge is power – especially when it comes to skincare. So, any questions?


Even if both were to contain the most innocuous of ingredients, the scientific fact remains: oil is hydrophobic – it simply won’t mix with water. Using an oil-based product leaves a coating on your skin that hinders water-based products from absorbing. However, they can be used in the same sitting if the water-based formula is applied first. But if you find yourself applying serum first and cleanser last on account of this information, stop.


Beloved for brightening complexions (amongst other things), there’s something about vitamin C that suggests amicability. How could an active ingredient with such a sunny demeanour ruin others’ chances at success? In truth, vitamin C is more of a bratty child star.

As Dr Kubicka states, “vitamin C should be used on its own as it oxidises very easily and can be deactivated when used with other active ingredients.”

The most disastrous of these combinations involves beta and alpha hydroxy acids such as salicylic acid and lactic acid. Another term for vitamin C is ascorbic acid (named as such in the last century because ascorbic means ‘anti-scurvy’), and layering it with the aforementioned acids does not make for a compatible cast of skincare ingredients – only irritation. There’s also the fact that it’s unstable: any AHAs or BHAs it’s used with could render it ineffective.

That said, we feel it is important to note that vitamin C’s incompatibility with niacinamide is a myth. A 2009 study published in the Journal of the American Academy of Dermatology found that a combination of both was still able to decrease melanin production in response to UV exposure: the presence of niacinamide hadn’t scuppered the benefits of vitamin C, in other words.

Ultimately, vitamin C should be applied “in the morning in the form of a serum and then followed by a light moisturiser and SPF,” says Dr Kubicka.


This is where things get complicated. Dr Kubicka tells us that “the main ingredients to avoid mixing are salicylic acid and retinol – as well as high percentage glycolic acids – as they individually are quite active and, when combined, will cause irritation and compromise the skin’s barrier.” For Lars Fredriksson, Founder of Verso Skincare, “a healthy skin barrier is the best way to withstand [skin] issues.” While no respectable authority on skincare would deny the importance of a healthy skin barrier, Consultant Dermatologist Dr Anjali Mahto is keen to remind us that retinol and AHAs do not necessarily have to be at war with each other if used thoughtfully.

“If you are concerned about the changes associated with premature skin ageing such as fine lines, wrinkles, and pigmentation then using both AHAs and retinol (in conjunction with daily sunscreen) should be the solid backbone of your routine,” she says. Why? “AHAs will cause chemical exfoliation of the skin by breaking down bonds between skin cells to leave brighter skin tone and texture as well as boosting collagen (the protein which gives our skin its structure). Retinol increases skin cell turnover, stimulates collagen and can help correct pigmentation,” she explains.

According to Dr Mahto, “there are some common myths propagated over and over again that these two ingredients should not be used together.” But there is “little scientific data'' to prove either that AHAs reduce the effectivity of retinol if used simultaneously, or that “AHAs reduce the pH of the skin and in this process deactivate the enzyme that converts retinol into retinoid acid (the active form of vitamin A used by your skin).” In actuality, issues of compatibility arise between them when they are not used cautiously – not automatically.

To put it simply: “their use needs to be gradually introduced and built up over time otherwise there is a real risk of developing irritation, redness, peeling and even swelling or dermatitis.” Indeed, it may well be the case that “those with sensitive or very dry skin” simply cannot tolerate both agents being used at the same time. Interestingly, however, “if your skin is on the oily side you are likely to manage the combination much better,” Dr Mahto reveals. Either way, the incorporation of both AHAs and retinol into your skincare routine must be done slowly. “Think about using an AHA-based face wash at night (it will be rinsed off so the contact time with your skin is short) and over time see if your skin can tolerate this regularly,” advises Dr Mahto. “Once you are able to do this without too many issues, then introduce a retinol into your routine (start with 0.1-0.3%) after cleansing which can be left on overnight.”

Of course, the speed at which your skin will adjust to these ingredients is deeply personal: “if your skin feels dry, tight or sore then don’t plod along for the sake of it,” Dr Mahto reminds us. In fact, “if you find this method too harsh for your skin then you may be better off alternating the products. Consider either using an AHA wash in the morning and retinol at night OR use AHA and retinol on alternative nights so your skin isn’t being hit with both at the same time.”

ESTÉE LAUDER Perfectionist Pro Rapid Brightening Treatment with Ferment²+ Vitamin C, £86

First Aid Beauty Eye Duty Niacinamide Brightening Cream, £28


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