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What Is Serum? How It Can Help Your Skin and How to Choose the Best Formula for You

The most powerful product in your skincare routine.
What is serum

When it comes to skincare, we all know the basics: cleansing, moisturizing and protecting our skin from the sun. But to really get the most out of your routine, serum is the answer.

You've no doubt seen and already tried some of the countless serum formulations on offer. There are hydrating serums, brightening serums, anti-aging serums and calming serums, to name just a few types. Heck, there are even serums that promise to do all of the above. 

So are they actually worth it? And how do you choose (and use) the right one?

In this tutorial, you will learn what serums do (and why they're more effective than creams), the different types of serums, and how to incorporate them into your skincare routine.

What Is Serum?

Serum is a topical treatment product that efficiently delivers active ingredients into your skin. Think: vitamins, antioxidants, acids, peptides, botanical extracts and more.

Because of its thin, liquid texture, serum is the ideal way to get the maximum benefits from these substances. 

A moisturizer's main job is to prevent water loss, so when active ingredients are present, they're alongside thicker emollients (like oils and butters) that can interfere with penetration. 

But serums are typically water-based, so when you apply one to your bare skin, the active ingredients can sink in quickly and start getting to work right away. What's more, by leaving out the heavy moisturizing agents, serum also contains a higher percentage of actives.

As a general rule, serum is meant to be used after cleansing and before moisturizing.  

Why Use a Serum?

Here are some of the reasons to love serums:

  • Lightweight: By nature, serums have a thin, fluid texture—so they don't feel like you're wearing anything on your skin.
  • Fast-absorbing: While creams and oils contain occlusive ingredients that can form a barrier on top of your skin, serums are made from very small molecules that penetrate quickly and deeply.
  • Non-comedogenic: Most serums, especially if they are oil-free and silicone-free, are unlikely to clog pores or trigger acne. 
  • Targeted: No matter what skin issue you are looking to improve, from dullness to fine lines to dark spots, there's a serum for that. 
  • Concentrated: The active ingredients in serums are present at a higher concentration than in other products (like face creams). 
  • Effective: Thanks to their higher dose of actives and ability to deeply penetrate, serums will give you better and faster results than most other topical skincare products.
  • Easy to layer: Since serums have a weightless texture, you can easily layer them under your other skincare products (such as moisturizers, face oils, sunscreens and foundations).

Which Type of Serum Is Best for You?

When it comes to choosing a serum, certain formulas are universally beneficial, while others are intended for specific skin concerns. 

The most common types of serums include:

  • Hydrating serums
  • Antioxidant serums
  • Brightening serums
  • Resurfacing serums
  • Clarifying serums
  • Pore-minimizing serums
  • Anti-aging serums
  • Calming serums

Here's what you need to know about each type.

Hydrating Serums

ClarityRx Daily Dose of Water Hyaluronic Acid Hydrating Serum

ClarityRx Daily Dose of Water Hyaluronic Acid Hydrating Serum

  • Purpose: Hydrating serums deliver an extra layer of moisture underneath face creams, face oils or sunscreens. They do so using humectants, which are ingredients that draw water into the stratum corneum (top layer of skin).
  • Key ingredients: Hyaluronic acid, glycerin, aloe vera, snail mucin.
  • Best for: All skin. 
  • Products to try: The simplest and best hyaluronic acid formulas I've tried include ClarityRx Daily Dose of Water Hyaluronic Acid Hydrating Serum, Timeless Hyaluronic Acid 100% Pure and SkinCeuticals Hydrating B5 Gel. (I try to avoid low-molecular weight varieties, since they are linked to inflammation.) There's also Consonant HydrExtreme, a two-ingredient serum containing glycerin and a naturally-derived sugar that is proven to outperform hyaluronic acid (!). Snail mucin is another great hydrator with both humectant and emollient (skin-softening) properties. Benton Snail Bee Ultimate Serum is 70% snail mucin.

    Antioxidant Serums

    SkinCeuticals C E Ferulic

    SkinCeuticals C E Ferulic

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    Brightening Serums

    Summer Fridays CC Me Serum

    Summer Fridays CC Me Serum

    • Purpose: Brightening serums focus on boosting radiance, evening out skin tone and fading dark spots, post-acne marks and hyperpigmentation. This is accomplished with ingredients that inhibit melanin production or prevent melanin transfer, or with chemical exfoliants that remove dead, pigmented cells. Sometimes, brightening serums also contain light-reflecting particles that impart an instant luminous effect.
    • Key ingredients: Vitamin C, niacinamide, kojic acid, alpha arbutin, tranexamic acid, hydroxy-acids.
    • Best for: Dullness, dark spots, hyperpigmentation. (Just be aware that L-ascorbic acid may not be suitable for sensitive and acne-prone skin.)
    • Products to try: Summer Fridays CC Me Serum is one of my favourites because it contains two types of vitamin C derivatives along with niacinamide. I also swear by SkinCeuticals Discoloration Defense, a dark spot-fighting serum that combines niacinamide with tranexamic acid, kojic acid and HEPES (a synthetic acid). If you can tolerate mild acids, consider Tatcha Violet-C Brightening Serum, which gets you glowing with 20% vitamin C derivative and 10% fruit-derived AHAs.

    Resurfacing Serums

    Biossance Squalane Lactic Acid Resurfacing Night Serum

    Biossance Squalane + Lactic Acid Resurfacing Night Serum

    • Purpose: Resurfacing serums, also known as retexturizing serums, are leave-on exfoliating treatments. They contain AHAs, BHAs, or a blend of both—which dissolve dead skin cell build-up and create a smoother skin surface. Since they're milder than most acid toners, these serums can often be suitable for sensitive skin.
    • Key ingredients: Lactic acid, glycolic acid, salicylic acid.
    • Best for: All skin. (But sensitive types should stick with lactic acid.)
    • Products to try: My top pick is Biossance Squalane + Lactic Acid Resurfacing Night Serum, which has a high 10% concentration of lactic acid, and is meant to be worn nightly. Drunk Elephant T.L.C. Framboos Glycolic Night Serum is even stronger, with 11% AHAs and 1% salicylic acid (but be careful with it—personally, I can't use that much glycolic acid without getting irritation). Also consider Tata Harper Resurfacing Serum and Herbivore Prism 12% AHA + 3% BHA Exfoliating Glow Serum, which both contain natural AHA-BHA blends.

    Clarifying Serums

    Juice Beauty Blemish Clearing Serum

    Juice Beauty Blemish Clearing Serum

    • Purpose: Clarifying or blemish-clearing serums treat active breakouts and prevent future ones while also helping to reduce excess oil. The best ones contain BHAs, which penetrate below the skin surface to deep-clean pores and regulate oil production. They're often paired with other ingredients that take down inflammation and reduce redness.
    • Key ingredients: Salicylic acid, willow bark extract, zinc, niacinamide.
    • Best for: Breakouts, oily skin, clogged pores.
    • Products to try: The best clarifying serum I've tried is definitely Juice Beauty Blemish Clearing Serum, which has 0.75% salicylic acid. That makes it a good choice for anyone seeking a mild but effective acne treatment (most toners have 2% salicylic acid, which can be too strong for some people). Also consider Derma E Acne Blemish Control Treatment Serum with 0.5%, and Caudalie Vinopure Skin Perfecting Serum (although the latter brand doesn't disclose its concentration). For an even gentler approach, go for Versed Just Breathe Clarifying Serum, a mix of willow bark, zinc and niacinamide.

    Pore-Minimizing Serums

    Paula's Choice Niacinamide 20 Treatment

    Paula's Choice Niacinamide 20% Treatment

    • Purpose: Pore-minimizing serums work on reducing the look of large pores. Often, this is because they've become congested and stretched out—so these serums contain ingredients that exfoliate inside the pores, loosen clogs and decrease sebum secretion. They also help to clear hardened, under-the-skin bumps and smooth out "orange peel" skin texture.
    • Key ingredients: Niacinamide, salicylic acid, mushroom extract.
    • Best for: Large pores, clogged pores, "orange peel" texture.
    • Products to try: Paula's Choice Niacinamide 20% Treatment is the most potent serum available for pore-related issues, boasting the highest concentration of niacinamide on the market. Go for this one if you have significant congestion and textural issues. Otherwise, some lower-dose options include Paula's Choice 10% Niacinamide BoosterPeach & Lily Glass Skin Refining Serum and Pacifica Pore Warrior Booster Serum, which are all niacinamide-based. Dr. Dennis Gross Alpha Beta Pore Perfecting & Refining Serum works a bit differently. It prevents pore blockages with salicylic acid, and minimizes pores with Argarikon mushroom extract.

    Anti-Aging Serums

    Pacifica Clean Shot Granactive Retinoid 5 in Seawater

    Pacifica Clean Shot Granactive Retinoid 5% in Seawater

    • Purpose: Anti-aging serums target fine lines, wrinkles, loss of elasticity and loss of firmness. As a bonus, they often help with dullness, dark spots and pigmentation concerns at the same time. These serums are powered by ingredients with a wide range of benefits, which include regulating collagen formation, relaxing wrinkles and plumping the skin.
    • Key ingredients: Retinoids, peptides, bakuchiol, vitamin C, hydroxy acids.
    • Best for: All signs of aging, including fine lines, wrinkles and loss of firmness.
    • Products to try: In my opinion, retinoids are always your best bet for improving the signs of aging. If you're concerned about irritation, Pacifica Clean Shot Granactive Retinoid 5% in Seawater gives you a high dose of granactive retinoid, a non-irritating retinoic acid ester, in a simple, water-based serum. That said, retinol is still the most proven over-the-counter retinoid, so I love Shani Darden Retinol Reform, which has 2.2% encapsulated retinol plus 2% lactic acid. Copper peptides, found in Dr Roebuck's Ningaloo Firming Serum, and bakuchiol, found in Herbivore Bakuchiol Retinol Alternative Smoothing Serum, are other anti-aging ingredients with good proof behind them (and they won't irritate your skin).

    Calming Serums

    Kristina Holey Marie Veronique Soothing B3 Serum

    Kristina Holey + Marie Veronique Soothing B3 Serum

    • Purpose: Calming serums soothe sensitive skin, decrease redness and irritation, and help to strengthen a weakened skin barrier, making your skin more resilient. This is accomplished with ingredients that take down inflammation, restore the moisture content of the stratum corneum, and seal up the cracks between skin cells.
    • Key ingredients: Niacinamide, ceramides, Centella Asiatica extract, propolis.
    • Best for: Sensitive skin, redness.
    • Products to try: Not only does Kristina Holey + Marie Veronique Soothing B3 Serum contain 10% niacinamide (which is proven to restore barrier function and reduce redness), it's also made without any fragrance, essential oils or other ingredients that could trigger allergies or skin reactions. The ceramides in Skin Inc Supplement Bar Ceramide Serum work by replicating the natural balance of lipids found in healthy skin. And although it's marketed for acne sufferers, all skin can benefit from GEORGANIC Propolis Acne Care Serum. I love it because it contains 78% Centella Asiatica extract, 10% propolis and 2% niacinamide, all of which are super-soothing, healing and anti-inflammatory.

    How to Add a Serum to Your Skincare Routine

    Ready to add one or more serums to your routine? Here's how to go about it.

    1. Wash Your Face

    Any dirt, oil or other products on your skin can block serums from absorbing, so start with a good cleanse. You may want to follow up with toner to ensure that all traces of cleanser residue are removed. (But if you plan to apply any acidic ingredients in your routine, just make sure your toner plays well with them—I've found that many hydrating toners don't. I recommend the toners from Pyunkang Yul, Glow Recipe and Benton.)

    2. Exfoliate (Optional)

    For best results, it's always a good idea to exfoliate prior to using active skincare products like serums. This is because dead skin cells can form an invisible barrier on top of your skin that will interfere with absorption. A mild acid treatment such as First Aid Beauty Facial Radiance Pads or Farmacy Deep Sweep 2% BHA Pore Cleaning Toner should do the trick to remove them, but if you're planning to use a resurfacing serum, you can skip this step.

    3. Apply Acidic Serums

    Now, you're ready to apply your serum. Acidic serums, which have a pH around 2.5 to 4.0, should always go on first. Often, brands will list the pH, but if your serum contains L-ascorbic acid, AHAs or BHAs, it is likely to be acidic. You can apply an acidic serum straight after your acid exfoliant (if you're using one), since both products will have a similar pH level. Remember that serums are super-concentrated, so you'll only need a few drops.

    4. Wait 20-30 Minutes

    I always recommend incorporating a waiting period of about half an hour in between acidic and non-acidic products. That way, they each have enough time to do their jobs at their intended pH levels. Otherwise, when you mix two products that have a big difference in pH, you can actually make one or both of them ineffective. In some cases (like with niacinamide and hydroxy-acids), you can even produce a red, inflammatory flushing reaction if they're applied too close together.

    5. Apply Non-Acidic Serums

    Now that you've waited after applying your AHAs, BHAs and/or L-ascorbic acid, you can proceed with your non-acidic serums. (Or, if you didn't use any acidic products at all, you can jump straight to this step.) Niacinamide, most vitamin C derivatives, retinoids, peptides, bakuchiol, and any calming or hydrating ingredients are all non-acidic and typically have a pH between 4.5 and 7.0.

    6. Apply Other Skincare Products

    Once your final layer of serum has absorbed, it's a good idea to seal it in so that any humectants in the formula don't evaporate, and the moisture stays locked in your skin. You can do this with a face cream, a few drops of face oil or even just sunscreen.

    Conclusion

    Now you know the benefits of including a serum in your routine, and how it can change your skin for the better!

    Not only does serum contain the most concentrated dose of active ingredients that you can find in over-the-counter skincare products, but it also has the ability to penetrate deeply, giving you maximum results. 

    You just need to choose the right serum formula, with the right ingredients, and hopefully I've helped with that! 


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