Retinol is one of those skincare ingredients that has a lot of misinformation surrounding it. We're often asked if AHA and BHA exfoliants reduce how effective your retinol formula can be. Or whether retinol should be in the same routine as vitamin C? Or about the combination of retinol & niacinamide and if it's safe?

What shouldn't I use with retinol?

As always, we turn to the research to bring you the facts.

What shouldn't I use with retinol?

Our only caution comes when you’re using multiple formulas that contain retinol, which includes other forms of retinoids (like stronger, prescription-only products). Though there is no harm in pairing them, you should be aware of the increased risk of skin sensitisation.

So, can you use retinol in the same routine as other active ingredients?

Yes. There is no research anywhere that supports the claim that retinol is deactivated when combined with acidic ingredients. But there is plenty of research that demonstrates the opposite. In fact, cosmetic scientists who specialise in developing retinol formulas are quick to disprove this and we've asked around – a lot! Now we're breaking down the research, ingredient by ingredient...

Can you use retinol and AHA or BHA exfoliants?

Let's discuss whether you can pair AHA exfoliants, like mandelic or glycolic acid, with retinol. At the same time, we'll cover BHA exfoliants, like salicylic acid.

There is no research that demonstrates that AHA / BHA exfoliants deactivate or lessen the effectiveness of retinol when used in the same routine. In fact, whenever we see a comment about not using retinol with chemical exfoliants, the advice is never supported by research. Even still, it remains one of those myths that is so often repeated, even dermatologists tend to fall into it.

The claim about retinol not working with AHA or BHA exfoliants began with a misunderstanding about how skincare ingredients work together and how each affect the structure of the skin. So let's dig a little deeper...

Does the pH of AHA or BHA reduce how effective my retinol is?

There are worries about the acidity of chemical exfoliants lowering the skin's pH and so disrupting retinol's ability to work its anti-ageing, skin-smoothing benefits.

The reasoning behind this concern is that skin pH below 5.5 to 6 then carries an enzyme that's no longer able to convert retinol into its active form, retinoic acid. However the initial assumption here is that AHA and BHA lowers the pH of the skin, but that is not the case. Just like most rumours, this one started after a misunderstanding about the research.

One study (from 1999) mentions the issue described above, but it is not a credible source for the following reasons:

• The study wasn't performed on normal human proteins or healthy, intact skin (instead, a blend of animal and human proteins, and the pH relationship issue developed only when a fatty acid byproduct was added to the mix).
• To further complicate matters, the study states: "no clear optimal [pH range] was seen when the test was run without [fatty acid byproduct]."
• It was only used to compare how animal and human skin metabolises the form of vitamin A naturally present in the skin, not about how topical vitamin A (retinol) benefits the skin. Topically applied vitamin A does not substitute the body's development, or the function of retinoic acid.
• Retinol is a solid that must be dissolved in a carrier oil, which makes it a waterless ingredient. Its composition means that there is no pH to consider, even when it is layered with acidic ingredients, as you cannot establish a pH in a waterless product!

It's also worth noting that no research has since replicated the pH limitations of the 1999 study.

But does retinol work better when you're not exfoliating?

In short, no. Research has actually shown that retinol combined with well-formulated & gentle exfoliants (like AHAs) helps to fade hyperpigmentation and actually improves the results you get from both ingredients. We particularly recommend the 6% Mandelic + 2% Lactic Acid AHA Liquid Exfoliant in combination with your favourite retinol to disrupt discolouration and visibly reduce fine lines & wrinkles.

The belief that the skin's pH neutralises acidic skincare is misguided. A neutral pH is 7, yet our skin is naturally more acidic – even more so than thought in the one study often cited. Today's research demonstrates that skin's pH actually hovers between 4.7 and 5. Does this mean we have to raise our skin's pH in order to use a retinol? Of course not! We know from research that retinol works when applied to the skin, so it can work at the skin's naturally acidic pH.

Does retinol have exfoliating effects?

Some people claim that retinol itself can also exfoliate the skin, so you shouldn’t use it alongside AHA or BHA. But the truth is that these ingredients actually work in very different ways. To put it simply:

• Retinol is an antioxidant and an important cell-communicating ingredient. When it absorbs into the skin, it can actually "tell" living skin cells to make healthier, younger cells and enhance the production of new cells.
• Retinol stimulates cellular turnover from the deeper layers up – not in the uppermost layers. Those uppermost layers are where AHA or BHA steps in to help skin shed unhealthy, dead & built-up skin cells.
• Retinol in both over-the-counter and prescription-only products may cause flaking and peeling for some users. But flaking skin does not mean exfoliated skin, whether from retinol or chemical exfoliants. Flaking is simply a sign of irritation. If it persists when using your retinol (or any other formula) it's a sign to use it less often or stop altogether.

Can you use retinol and vitamin C?

Vitamin C (ascorbic acid and its derivatives) is another ingredient we are often told not to use at the same time as retinol. Again, this myth has stemmed from a pH/acidity issue.

The truth: vitamin C (depending on the form) requires a low, acidic or no pH to remain stable. We know retinol works well in an acidic environment and that our skin's pH is naturally acidic. Based on what the research has shown us, there is no problem with pairing vitamin C and retinol.

In fact, research has shown that combining vitamins gives the best results. Teaming retinol (vitamin A) with vitamin C together is a great way to defend your skin against free radicals (of course, always finish with SPF 30+). In this way, vitamin C actually helps retinol work better! Fighting free radicals is a process that helps protect retinol from oxidation as it penetrates the skin – thereby increasing the anti-ageing benefits.

Can you use retinol and niacinamide?

Retinol and niacinamide can definitely be combined for impressive results. Many dermatologists recommend this pairing because niacinamide keeps skin calm, while retinol gets to work reducing wrinkles. Research shows that these two ingredients work well in tandem to overturn signs of ageing at the same time as addressing issues like enlarged pores and uneven skin tone.

Can you use retinol in the daytime?

Retinol doesn't cause the same sensitivity to daylight as more potent, prescription-only forms of Vitamin A. But we do always recommend protecting the skin with SPF 30 or higher, come rain or shine. Research has shown that retinol and vitamin C work well under SPF moisturisers to protect the skin from UV light. Not to mention how vitamins A, C and E (even in combination) also remain stable and effective under an SPF-rated formula.

Research has stated that vitamin A together with vitamin E remains stable when exposed to UV rays and paired with SPF, as does pure vitamin A when used alone. That's excellent proof of retinol's stability when teamed up with sun cream.

Antioxidants plus SPF are a formidable defence against wrinkles, uneven skin tone, loss of firmness and brown spots. For best results, be sure to apply antioxidant-rich skincare formulas both morning and evening.