At The Ordinary, serums are typically used in the Treat step, the middle part of your regimen—after Prep (cleansing) and before Seal (moisturizing to lock in the benefits of serums and ingredients). During the Treat step, you can layer formulations to address specific skin concerns. For instance, if you’re targeting both hydration and signs of aging, you might choose two serums.

Before we get into the details, let’s break down what serums are, how they work, and how they can help address your specific skin needs.

A skin serums is a targeted skincare formulation designed to deliver high concentrations of ingredients to the skin.

Unlike traditional moisturizers, which are often thicker, serums are lightweight. They are often water- or oil-based, allowing them to penetrate deep into the skin's surface and address specific concerns.

On the other hand, cleansers and exfoliators remove impurities, makeup, and dead skin cells, preparing your skin for targeted treatments. This makes serums a powerful addition to any skincare regimen, offering benefits like hydration, improved skin texture, brighter-looking skin, and reduced signs of aging.

Serums usually contain a range of ingredients like antioxidants, vitamins, peptides, and acids. At The Ordinary, we offer two types of skin serums: targeted solutions with a single primary ingredient to address specific concerns, and multi-active solutions that provide a broader range of benefits.

Target Signs of Aging

Serums addressing aging concerns are often formulated with ingredients that help support skin’s natural collagen, improve skin elasticity, and minimize the appearance of fine lines and wrinkles.

Peptides and retinoids (such as retinol) are key ingredients often found in serums targeting signs of aging. Peptides support collagen and elastin, and help to firm and smooth skin’s feel, while retinoids help improve cell turnover, leading to younger-looking skin. Facial oils, such as rose hip oil, can also support skin elasticity and promote supple, more radiant-looking skin.

Manage Signs of Congestion

Signs of congestion can be a primary concern for oily and combination skin types. Serums formulated with zinc and niacinamide are beneficial for balancing sebum production, smoothing out skin texture, and refining visible pores. These lightweight ingredients also enhance skin brightness and strengthen the skin’s moisture barrier.

Boost Hydration

Serums formulated with ingredients like hyaluronic acid and vitamin B5 provide intense hydration. Hyaluronic acid is a fundamental molecule in supporting skin hydration and elasticity due to its strong abilities to bind to water, making it a powerful component for plumping and softening dry or dehydrated skin. Vitamin B5 supports skin barrier components, such as ceramides and fatty acids, enhancing moisture retention and promoting a healthy, radiant appearance.

Enhance Brightness

For a more radiant complexion, brightening serums can help skin tone look more even and address dullness. Key ingredients like vitamin C and niacinamide are commonly found in these formulations. Vitamin C is a potent antioxidant that targets uneven looking tone, texture, and signs of aging, while also offering antioxidant support. Niacinamide brightens and improves the appearance of uneven skin tone. Alpha arbutin is another well-known brightening ingredient that supports a smoother, more uniform-looking skin tone.

Support Skin Barrier Function

The skin barrier, or the outermost layer of the skin, is essential for keeping moisture in and irritants out. Serums that contain aloe vera or ceramides are beneficial for supporting and strengthening this barrier. A strong skin barrier helps prevent dryness, visible sensitivity, and other skin issues, leading to healthier-looking, more resilient skin over time.

Now that we’ve explored the key ingredients in skin serums, the next step to using them effectively is selecting one that suits your specific skin type and concerns. Here’s a guide to choosing the right serum for varying skin needs.

Skin Serum for Dry Skin

Hydration plays a key role in supporting dry skin. Look for serums with hyaluronic acid, an important molecule in supporting skin hydration due to its ability to bind to water; or squalane, a lightweight hydrator that mimics your skin’s natural oils. Products like Hyaluronic Acid 2% + B5 (with Ceramides) offer immediate and long-lasting hydration, while 100% Plant-Derived Squalane is a non-comedogenic solution that enhances surface-level hydration.

Skin Serum for Oily Skin

Oily skin benefits from lightweight, non-comedogenic serums that help reduce excess oil and minimize shine. Niacinamide 10% + Zinc 1% is a community favourite for oily or blemish-prone skin. This combination of ingredients can help control excess sebum, smooth skin texture and has a mattifying effect. Amino Acids + B5 is a water-based formulation that keeps the outer layer of your skin protected and well-hydrated without feeling greasy.

Skin Serum for Sensitive Skin

Sensitive skin can be reactive to ingredients, so it’s important to use gentle serums that soothe and support the skin barrier. Our Soothing & Barrier Support Serum is suitable for sensitive skin and helps reduce visible signs of redness and irritation.

Skin Serum for Glowing Skin

For a visibly brighter, more radiant complexion, consider incorporating a brightening serum into your routine. Ingredients like vitamin C and alpha arbutin are key: Vitamin C 23% Suspension + HA Spheres 2% targets uneven skin tone and dullness, while Alpha Arbutin 2% + HA can help reduce the appearance of dark spots, leaving the skin looking brighter and more even-toned.

Skin Serum that Targets Signs of Aging

Serums addressing signs of aging often contain retinoids or peptides to refine skin texture, reduce the look of wrinkles, and increase firmness. Retinoids like Retinol 0.5% in Squalane that improves the appearance of fine lines and wrinkles that arise from a loss of collagen and elastin, while evening skin texture and appearance of skin tone. Peptides, on the other hand, support skin elasticity, making them an alternative to retinoids.

Using serums correctly is key for achieving the best results. Here’s how to incorporate serums into your skincare regimen:

• Layering: Apply serums after cleansing but before moisturizing as part of our 3-step regimen, where serums are core to the Treat step. As a general rule of thumb, apply products from the thinnest to the thickest formulation. A more effective method, though, is to layer them by format—starting with water-based and anhydrous products, then moving on to oils, creams, and suspensions. Our layering guide covers this, and more.


• Frequency: This largely depends on the specific product. We always recommend following product directions. For strong ingredients like retinoids or direct acids, you may wish to start with application 2-3 times a week, gradually increasing frequency as your skin tolerates it. Please note, for Retinal 0.2% Emulsion, we recommend using a maximum of 2-3 times a week.


• Day or Night: Again, this depends on the product. As an example, apply products containing Vitamin C in the morning and retinoid-based products at night. Hydrators like hyaluronic acid can be used in both AM and PM. Always refer to the product’s usage instructions for specific guidance.

For those new to serums, it’s a good idea to start with a single serum and observe how your skin responds before introducing more products.

1. Serums Replace Moisturizer

Serums are not a replacement for moisturizers. While they contain actives, serums may lack the emollients needed to lock in moisture. To get optimal results, apply a moisturizer after your serum, as part of the Seal step in your regimen for skin hydration.

2. Serums are Only for Mature Skin

Serums are beneficial for all ages and skin types, as they address various concerns beyond signs of aging, including excess oil, hydration, and sensitivity.

3. The More, the Better

Applying too much serum or too many serums at once can overload the skin and cause irritation. Depending on the product or your custom regimen, we always recommend starting out slowly with one product at a time, and slowly incorporate more.

Skin serums are a focused step in any skincare routine, designed to address specific concerns like dryness, uneven tone, fine lines, and texture. Selecting the right serum and applying it as directed offers a tailored approach to supporting your skin’s unique needs.

Whether your focus is hydration, signs of aging, or brightness, there’s a serum to enhance your skin and give you solutions to your skin concerns.

For an individualized regimen plan where science meets customization, try The Ordinary’s Regimen Builder today and benefit from product recommendations tailored to your skin type and concerns.