The Skin Nerd: These are the ingredients you should never mix when layering skincare

Skincare ingredients you shouldn’t mix - and the exception to one nerdie rule

The Skin Nerd: Skincare isn't a pick and mix!

It is gifting season and whilst many of us will be delighted to receive a box of beauty must-haves, introducing any new product to your regime should always be a careful and considered process. 

As well as thinking about your skin type and goal, it is important to look at what ingredients are in the skincare products that you already use. 

The bigger picture should always be considered when it comes to skincare. 

This means looking at ALL the ingredients within your full regime to ensure you: 

a) don’t use too much of one thing, 

b) see what you may be lacking and 

c) consider whether all these ingredients work together as a team or fight against each other to potentially cause their own set of skin issues. 

Many ingredients blend together to ultimately create a wonderful skin recipe – but others are best kept apart. 

In fact, you should be particularly cautious when mixing active ingredients as overzealous use of these potent formulas can damage the skin barrier and cause irritation, dehydration and inflammation – not what you want to start the new year with!

It therefore goes without saying that your skin health depends on a thorough investigation of the ingredients you are combining pre-use to ensure they work together harmoniously. 

Here is a simple (and nerdie) guide to smartly layering ingredients to help you reach your skin goals.

Retinol and AHAs & BHAs 

Retinol is a form of vitamin A and is highly regarded in the beauty industry for its extensive benefits, which include the ability to boost skin cell turnover, stimulate the production of collagen and elastin, reduce pigmentation, address fine lines and wrinkles and improve skin texture – what a star, eh!

Due to its potency, retinol can cause skin sensitisation when alone, so as you can imagine, it can also do this when mixed with other active ingredients. 

This is especially likely when it is paired with exfoliating acids such as AHAs and BHAs which also promote the sloughing of dead skin cells. 

By using these ingredients during the same evening, you can potentially risk weakening the delicate skin barrier which can cause problems including dehydration, feelings of tightness and redness.

To air on the side of caution, ALWAYS follow manufacturer's instructions to the word. 

It is best to use these active ingredients on alternate evenings – or if you have particularly sensitive skin, you could start by using them on alternative weeks. 

Importantly, if you are unsure, don’t hesitate to ask a skincare professional for advice.

Nerdie tip: An exception to this rule is polyhydroxy acids (PHAs) as they are a more gentle AHA which are kinder to the skin barrier and also act as a humectant.

Retinol and Vitamin C:

Retinol and vitamin C are two powerhouse active ingredients that aren't always a perfect match either, so always proceed with caution when it comes to using these alongside each other within a routine. 

Vitamin C is a powerful antioxidant that has many skin benefits including boosting collagen, the ability to promote wound healing, neutralise free radical activity caused by UV exposure and pollution and the potential to lessen the appearance of dark spots. 

Vitamin C comes in lots of different forms but layering any of them with fellow powerhouse retinol can lead to irritation if care is not taken.

One way to include both is by applying vitamin C underneath your sunscreen in the morning, and to then use retinol at night to assist with the skin’s nightly regeneration and renewal processes. 

Alternatively, consider switching to the gentlest form of vitamin A - retinyl palmitate - which can be layered with vitamin C. 

I recommend the award-winning Skingredients Skin Protein Anti-Ageing Retinoid Serum (€55, skingredients.com). 

This game-changing formula contains retinyl palmitate AND vitamins C and E to stimulate the production of collagen and elastin, optimise the skin’s renewal process and reduce the appearance of open pores. 

Always follow with a broad-spectrum, high-factor SPF and reapply every two hours during the daytime as advised by Irish Cancer Society.

Vitamin C and Exfoliating Acids:

As mentioned above, if you are looking for antioxidant protection, vitamin C should be in your skincare arsenal, but it is also worth noting that it is an unstable ingredient that requires a certain pH balance to work its magic on your complexion. 

Subsequently, this means that it requires careful consideration to avoid overuse and the risk of causing any damage to the skin. For example, layering an exfoliating acid such as an AHA or BHA with vitamin C could potentially disrupt the pH balance and lessen any benefits of the vitamin C.

Unless the product manufacturer's instructions specifically say otherwise, I suggest taking precautions by using vitamin C in the mornings and reserving AHAs and BHAs for night-time regimes (on a night you are not using retinol). 

This not only gives the exfoliating acids a little space from vitamin C, but also helps to mitigate the fact that exfoliating acids can weaken our skin’s resilience to UV damage – even if you are consistently applying broad-spectrum SPF.