Main content
adding serum to skin routine

4 min read

Want to get more from your skincare, without spending hours in the bathroom? The answer Is often as simple as adding a facial serum to your routine. Lightweight and easily absorbed, serum penetrates the skin to deliver a concentrated dose of antioxidants, vitamins, and active ingredients. Targeting hyperpigmentation, wrinkles, dehydration, acne and more, they’re the easy way to supercharge your skincare routine – as long as you know how to use them.

For everything from the correct way to layer serum and moisturiser to the ingredients to look out for, read on. Our AM to PM serum guide explains how to add a facial serum to your morning and night skincare routines for maximum results, minimum effort.

A quick tip: a perfect serum AM PM pairing starts with a soothing, hydrating or brightening serum in the morning, and a targeted serum at night. Our Toleriane Ultra Dermallergo Hydrating Serum and Retinol B3 Anti-Ageing Serum are a perfect pair so if you're unsure where to start, start with these serum friends!

exfoliating skin


Do you use a Vitamin C serum morning or night? And can you apply retinol during the day?... Before you start applying serums willy-nilly, it’s important to know which ingredients work best, when.

Many gentle serums, such as a hydrating Hyaluronic Acid Serum, barrier-boosting niacinamide serum or soothing, Anti-Redness Serum are effective applied morning and/or night. However, others are designed for use at a specific time, such as before sun exposure or sleep.

Skin brightening, hydrating and collagen boosting, a Vitamin C serum sits firmly in the ‘best for AM use’ category. This is because Vitamin C is rich in antioxidants, which help to mitigate the free radical damage – and subsequent signs of photo-ageing – triggered by UV radiation.

If you’re using a single serum in the morning, it’s therefore smart to prioritise an antioxidant serum, such as La Roche-Posay’s Vitamin C 10 Brightening Serum. If layering a second serum (no more than two are recommend AM or PM), apply the Vitamin C first.

La Roche-Posay Face Serum suitable for AM useVitamin C 10 Brightening Serum*, Hyalu B5 Hyaluronic Acid SerumToleriane Ultra Dermallergo Hydrating SerumRosaliac Ar Intense Anti-Redness Moisturiser

*Morning use recommended



Some stimulating ingredients, on the other hand, are best applied in your nightly serum routine. These include retinol, AHAS such as glycolic acid, and salicylic acid, which may increase sun sensitivity (particularly in high concentrations).

Another reason a refining, re-texturising Retinol Serum is ideal for night-time use is that the skin switches into renewal mode, and retinol supports its overnight processes. By helping to speed up skin cell regeneration, retinol can further enhance repair.

At the same time, skin also loses more moisture as you sleep. This means hyaluronic acid is also ideal for night-time use, especially if your skin is dry or dehydrated.

Want to layer your PM serums? Make sure you look at the ingredients first. Some pairings, such as retinol and exfoliating acids, can overstimulate skin and cause dryness, peeling or sensitivity. While no combinations are categorically off-limits, application of some ingredients is often best spaced out. Confused? Our guide to serum layering explains this in detail.

La Roche-Posay Face Serum suitable for PM useEffaclar Anti-Acne Salicylic Acid Serum*, Retinol B3 Anti-Ageing Serum*, Hyalu B5 Hyaluronic Acid SerumToleriane Ultra Dermallergo Hydrating Serum

*For evening use only – may increase sun sensitivity

hyaluronic acid


When layering serums and other skincare products, think thinnest to thickest*. This means applying serums to clean skin after your toner/mist (if using), and before moisturiser and sunscreen. If applying multiple serums, apply the thinnest first or, if they’re the same consistency, use the most important serum to ensure it has a clear pathway.

Whether you should moisturise after applying serum is a matter of preference and ingredients. If your serum contains no hydrating ingredients, you’ll likely benefit from using moisturiser. However, if it contains hydrators like glycerin and hyaluronic acid, you might be able to skip the moisturiser – especially if you’re oily or acne-prone.

Regardless of skin type, the final, most important step in any morning skin routine is applying a high-SPF broad-spectrum sunscreen! According to La Roche-Posay’s Scientific Communications Manager, Rachel McAdam, as sunscreen works by integrating and sitting within the crevices of the skin to form a shield, it’s best not to apply too many layers underneath. Since most sunscreens contain hydrating ingredients, this means that a separate moisturiser is often optional.

(*One exception to the thinnest to thickest rule is eye cream. This should be applied to clean skin, before serums.)

using retinol and niacinamide


If you add one serum to your anti-ageing regime, consider a product containing Vitamin C. 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 Vitamin C 10 Brightening Serum.

So, for younger looking skin longer, try pairing a Vitamin C serum with a high-SPF broad-spectrum sunscreen, such as Anthelios Invisible Fluid Facial Sunscreen SPF 50+, every single day.



For skin that feels dry, tight or flaky, add a hydrating serum to your morning and night routine to target these sensations and provide a skin moisture barrier boost. The serum stage of your AM or PM skincare regime is the ideal moment to add an additional layer of hydration. In the morning, this can give your skin a naturally plumped, fresh appearance, while at night hydrating ingredients can work to target dry skin while you sleep.

Vitamin B5, sometimes called panthenol, is a skincare ingredient used for it’s moisturising and comforting capabilities. You’ll find it in our multitasking Cicaplast B5 Serum alongside prebiotic Aqua Posae Filiformis to care for the skin microbiome, and HEPES to refine the skin surface. The innovative new formula works to provide 24 hour hydration and two times faster recovery of the skin moisture barrier from triggers that can cause dryness, redness, tightness and discomfort*. Apply 1-2 drops morning and night to clean, dry skin, and allow to sink in before continuing with your skincare routine. Don’t forget to follow up with your broad spectrum sunscreen when using in the morning.

*TEWL study on 25 women aged 18-65 at T00 before and T1h, T2h, T4h and T6h after stripping skin.



Serums differ from moisturisers in a number of ways. Firstly, while they may contain hydrating ingredients, facial serums perform a wider range of functions than moisturisers, which essentially form a physical barrier to lock in hydration.

With a thinner, lighter consistency, liquid or gel-like serums also penetrate the skin more deeply, thanks to smaller molecules. This, combined with their high concentration of one or more active ingredients, makes serums very effective at targeting specific skin concerns.

While it’s important to meet your skin’s basic needs first by cleansing, moisturising and applying sunscreen, serums are also worth considering. And if you want to delay or reverse signs of ageing, many skin experts consider them crucial.



What about layering a serum and a moisturiser with the same active ingredient – is this a ‘do’, or a ‘don’t’? Well, it depends on the ingredient, the dosages, and whether the skin will actually gain any additional benefit, says McAdam.

For instance, while layering up a hydrating ingredient such as hyaluronic acid (the hero of the La Roche-Posay Hyalu B5 Hyaluronic Acid Serum and Hyalu B5 Hyaluronic Acid Anti-Ageing Moisturiser) is a ‘do’, retinol layering is generally considered a ‘don’t’. It’s also best to take care layering exfoliating acids; however, there are always exceptions.

Those with acne, for example, may benefit from following a salicylic acid serum with a moisturiser also containing BHAs. In a night-time anti-acne routine, that means following the La Roche Posay Effaclar Anti-Acne Salicylic Acid Serum with Effaclar Duo (+) Anti-Acne Moisturiser – if tolerated.

For all ingredients, there is also a point at which the skin can’t take up anymore, and no further benefit will be gained. Take Vitamin C. 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.


1. Al-Niaimi F, Chiang NYZ. Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. J Clin Aesthet Dermatol. 2017;10(7):14-17.


Stay In Touch

Orientation message
For the best experience, please turn your device