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Skincare Routine Order: Serum Layering


Skincare Routine Order: Serum Layering

Delivering a concentrated dose of active skincare ingredients, serums offer multiple benefits, from a brighter complexion to smoother, firmer, more hydrated skin. But, with countless options, it can be hard to know which serum to start with. Added to that are the questions of where they sit in your skincare routine, how many you can use, and how to layer serums for optimal results… If you’re considering adding serums to your skincare routine and want to make sure you’re doing it right, read on. Our no-nonsense guide to skincare layering outlines the ingredients you can and can’t mix, tips for successful serum layering, and the correct order for applying all skincare products – from cleanser to eye cream to sunscreen.

Skincare Ingredients You Should Never Mix

While certain active ingredients should be layered with care, according to La Roche-Posay’s Scientific Communications Manager, Rachel McAdam, there are no ingredients you categorically cannot mix. Instead, it’s a matter of adding new ingredients cautiously – ensuring you combine any active ingredients in a concentration tolerated by your skin, while always following the advice of your dermatologist.   In other words, it’s important to take things slowly when introducing serums (or any skincare products), monitoring your skin’s response before increasing usage frequency or adding another active.

Skincare Ingredients You Can Mix

To help you shop for the right skincare, we’ve created a comprehensive – but not exhaustive – list of serum ingredients that work well together. Something to note is that, while some compatible ingredients can be combined in one serum, others do not combine well in a single formula. This doesn’t always mean they shouldn’t be used together – but that they might require different delivery vehicles, or that they might neutralise each other’s activity.   Therefore, you may sometimes need to layer serums rather than reach for an all-in-one ‘solution’. This is especially the case if you have several different skin concerns or goals.

1. Retinol and Hyaluronic Acid

If there’s one ingredient that plays nice with others, it’s skin-plumping, hydration-boosting hyaluronic acid. “There’s no problem with hyaluronic acid’s interaction – it hydrates, it carries water, so it’s always going to give a good outcome,” says McAdam.  A naturally occurring component in the skin, hyaluronic acid partners well with retinol as it helps combat any drying effects of the anti-ageing Vitamin A derivative.   (Can’t see hyaluronic acid in the ingredients? It often appears as sodium hyaluronate – HA in its water-soluble form that is easily assimilated by the skin.)

2. Vitamin C and Retinol

For brighter, more refined skin, Vitamin C and retinol are the dream team. However, they’re not often combined in a serum. “Vitamin C is acidic so it has a lower pH vehicle and retinol is quite neutral, so it doesn’t have as low a vehicle,” says McAdam. This means the ingredients generally require different formulas for effective delivery into the skin. While Vitamin C and retinol can be layered (with care), the best way to apply these is according to their actions. As Vitamin C is a powerful antioxidant, it’s most beneficial applied in the morning, before sun and pollution exposure. Retinol, on the other hand, is ideal for nighttime use, partly because it makes the skin more sensitive to the sun, but mainly because it works best when the skin is in repair mode. “Retinol affects the skin’s own behaviours and helps it do different things like turn over a little better, which makes it best suited to nighttime use,” says McAdam.

3. Retinol and Niacinamide

Retinol and niacinamide (Vitamin B3) have a direct compensation benefit, as retinol stimulates the skin while niacinamide helps strengthen. These ingredients can therefore be layered in different serums and creams. Alternatively, as they both have a neutral base and are neither acidic or alkaline, they can combined, such as in the La Roche-Posay Retinol B3 Serum.

4. Vitamin C and Niacinamide

Much like hyaluronic acid, niacinamide or Vitamin B3 can be used with most other ingredients – including Vitamin C. “Used in separate products, Vitamin C and niacinamide work very well together. The Vitamin C acts as an antioxidant and the niacinamide has multiple benefits including brightening, so it will add to Vitamin C’s brightening benefits, while also soothing the skin and helping visibly reduce redness,” says McAdam.

5. Vitamin C and Hyaluronic Acid

Both hyaluronic acid and ascorbic acid (water-soluble Vitamin C) exist naturally in the skin and contribute to a firmer, glowing complexion. By improving the skin’s moisture-retention processes, hyaluronic acid helps to re-plump and revitalise dry, dehydrated or dull skin, while Vitamin C is known to help stimulate collagen synthesis and help reduce photo-ageing through its antioxidant benefits.   These popular serum ingredients can be layered, or applied at different times of the day. If spacing apart, it’s best to make Vitamin C part of your morning skincare routine, with Hyaluronic Acid at night. If layering, Vitamin C should be applied first to maximise its antioxidant benefits.

6. Vitamin B5 and Vitamin C

With repairing and soothing benefits, Vitamin B5 (or pantothenic acid) also exists in our body and is generally well tolerated. There is no interaction with Vitamin C and B5 can be combined or layered with the antioxidant. A humectant, Vitamin B5 also assists with moisture retention and is therefore highly compatible with hyaluronic acid – you’ll find the combination together in our Hyalu B5 Serum.

7. Vitamin C and Salicylic Acid

Layering isn’t strictly a no-no, but it’s often recommended Vitamin C and salicylic acid, with its exfoliating, pore unclogging action, be used at different times of the day. This is because the combination can be drying, depending on dosage.   Although some argue they shouldn’t be combined in a single formula, this isn’t always true. “Both Vitamin C and salicylic acid are acidic and hence require a low pH,” says McAdam. “The pH of pure ascorbic acid is quite low – usually under 3 – and the pH of pure salicylic acid is 3-5. So, they can co-exist quite well. However, if there is too much salicylic acid it may bring the pH up slightly and this can reduce the viability of Vitamin C.”

However, when salicylic acid is included in a low concentration as a supportive ingredient, such as in the La Roche-Posay Pure Vitamin C10 Serum, this issue is removed. “The serum is high in Vitamin C with a small amount of salicylic acid (<1%) added to boost exfoliation and brighten the skin,” says McAdam. “The concentration is compatible with the Vitamin C without altering the overall pH of the formula – hence keeping the Vitamin C in the formula very stable.”

Skincare ingredients to combine with Caution

While not a definite ‘don’t’, there is one combination that needs to be treated with particular care. 

Retinol and Acids (AHAs, Salicylic Acid, LHA)

Combining retinol and alpha-hydroxy acids, such as glycolic acid, or beta-hydroxy acids such as salicylic acid and LHA, should be done with considerable caution – particularly at higher concentrations.   “You always have to be careful not to put too many products on the skin with similar actions and similar ingredients so that you don’t get a compounding irritation or side effects, such as redness or peeling,” says McAdam.   It’s therefore often best to seek routine advice from a dermatologist, who may suggest spacing out applications for example.

How to layer serums

Now you know which active ingredients play nicely together, here are some serum layering tips to consider.

1. Apply Serums to Clean Skin

Serums work best on bare skin, so it’s beneficial to prepare by cleansing. However, it’s also crucial to respect the skin’s barrier function and avoid over-cleansing which can break down good fats and cause dryness and irritation.   According to McAdam, while not always essential, morning cleansing helps remove the byproducts of the skin’s metabolic processes that occur overnight. “Skipping cleansing is not going to destroy any outcome from your serum completely, it might just reduce some of the integration and absorption within the skin,” she says.    As for whether you should double cleanse at night, there’s no right or wrong. “One layer is often enough; however, if you’re removing makeup then you can do another round of cleansing,” says McAdam.   Struggling to remove the day with a single cleanse? Start with a micellar water to help lift makeup and impurities.

2. How many Serums to Use

With serums, more is not always more. Dermatologists deal with a lot of overly stimulated, overly reactive skin – and that often comes from using too many ingredients at once.   It’s best to therefore stick with layering no more than two serums, morning and/or night. Introduce them slowly starting with what’s most important to you, whether that’s fighting pigmentation, reducing redness, tackling dehydration or smoothing wrinkles.   Once your skin is tolerating a serum and you see some benefit, you can add another. If something’s not yielding results, take it away and try something else.  

3. How much time to leave before apply serums

While there’s no set rule, you should leave a few minutes between applying serums. This allows each product to be integrated within the epidermis so the skin can uptake what it needs. Applying a second serum too quickly can dilute the first round, or you might lift some product away with your fingers.

How to Use Face Serums with Moisturisers

When layering skincare, thinnest to thickest is your rule of thumb. This means applying serums before moisturiser and sunscreen. And, for serums with the same consistency? Apply the most important serum first to ensure it has a clear pathway.   According to McAdam, whether you moisturise after serums depends on preference and ingredients. If a serum has one active ingredient, such as retinol, with no hydrating ingredients, you’ll likely benefit from applying a moisturiser. However, if your serum contains hydrators like glycerin and hyaluronic acid, it may be an option to skip the moisturiser.     One exception to the thinnest to thickest rule is eye cream. If using, these should be applied after cleansing and before serums. Avoid the eye area when applying your serums, unless specified otherwise. If a serum is specified for the eye area, it can be applied first.

Layer Products with the Same Active Ingredient

So, can you follow a serum with a moisturiser containing the same key ingredient? You can, but it depends on the dosages, and whether the skin will gain any additional benefit from doing so.   For all ingredients, there is a point at which the skin can’t take up anymore, and no further benefit will be gained. Take Vitamin C for instance. Evidence shows that exceeding a 20% concentration can lead to irritation, with no greater result1. Furthermore, too much topical Vitamin C can give fair skin an orange tint.

Layering Moisturiser and Sunscreen

It’s generally accepted sunscreen should be the final step in your morning skincare routine – after any serums and moisturiser. However, it’s important to note that sunscreen works by integrating and sitting within the crevices of the skin to form a shield. If you have too many layers or thick products underneath, its shield integrity might be compromised. According to McAdam, as most good sunscreens will have hydration in them, you could consider whether you actually need a separate moisturiser. Particularly if there is hyaluronic acid in the serum, and then glycerin in the sunscreen. If you’re going to be exposed to UV, sunscreen should always take priority.

Vitamin C and Sunscreen
If you’re to add one product to your anti-ageing regime, a serum containing Vitamin C is a smart choice. A powerhouse antioxidant that helps protect skin from free radical damage caused by environmental aggressors, Vitamin C has been proven to enhance the protective benefits of sunscreen.   Various studies have also shown Vitamin C’s ability to prevent photodamage is further enhanced when combined with Vitamin E (tocopherol) – as in the La Roche Posay Pure Vitamin C10 Serum.

How to Layer with La Roche-Posay: Example Skincare Routines

1. Anti-Ageing, For Dry to Combination Skin

Cleanser from Toleriane range
Redermic Vitamin C Anti-Ageing Eye Cream Pure Vitamin C10 Serum
Hyalu B5 Anti-Ageing Moisturiser Anthelios SPF 50+ sunscreen – XL Ultra-Light (normal to combination) or Ultra (dry skin)  

Cleanser from Toleriane range
Redermic R Anti-Ageing Eye Cream
Retinol B3 Serum Hyalu B5 Serum and/or Hyalu B5 Anti-Ageing Moisturiser   

2. Ultra-sensitive or allergy-prone skin
Toleriane Dermo-Cleanser
Toleriane Ultra Dermallergo Serum
Toleriane Ultra Eye Contour Cream
Toleriane Ultra-Sensitive Moisturiser
Anthelios SPF 50+ sunscreen of choice     

Toleriane Dermo-Cleanser
Toleriane Ultra Dermallergo Serum
Toleriane Ultra Eye Contour Cream
Toleriane Ultra Overnight Sensitive Moisturiser

3. Oily and Acne-Prone Skin
Effaclar Foaming Gel Cleanser or Micro-Peeling Purifying Gel Cleanser
Redermic Vitamin C Anti-Ageing Eye Cream
Serozinc Toning Mist Pure Vitamin C10 Serum (not suitable for acne-prone skin)
Effaclar Duo (+) Anti-Acne Moisturiser
Anthelios XL Anti-Shine Dry Touch Sunscreen SPF50+  

Effaclar Foaming Gel Cleanser or Micro-Peeling Purifying Gel Cleanser
Redermic R Anti-Ageing Eye Cream
Serozinc Toning Mist
Effaclar Duo (+) Anti-Acne Moisturiser  

ALWAYS READ THE LABEL. FOLLOW THE DIRECTIONS FOR USE. Apply 20 minutes before sun exposure. Sunscreen is only one part of sun protection so wear protective clothing and seek shade. Avoid prolonged sun exposure. Reapply every 2 hours and after swimming, towelling and perspiring in accordance with directions.

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