Facial Serums vs Facial Moisturizers - The Differences Explained For Your Routine

(My contribution to the skincare blog: Kiseu.)

If you’ve been into K-beauty for long, you know by now that hydration is a major key to good skin. Two of the staple products in the 10-step Korean routine to achieve this are serums and facial moisturizers. 

But how are these products different, and do you really need to use two different hydrating products? Today, we’re breaking down the merits of facial serums and facial moisturizers, so you don’t have to wonder anymore. 

Serums VS Moisturizers: What’s the Difference? 

So, you already know that both these products aim to moisturize your skin, but they each have their own benefits and limitations. 

Let’s start with serums. Serums are usually very thin and watery. This is because their formulas leave out the thickening agents common in most moisturizers. Their light texture ensures that they deliver high concentrations of active ingredients to your skin. 

Serums soak in fast to hydrate your skin, penetrating to layers deeper than most moisturizers can reach. They’re often designed to focus on one skin issue, like minimizing fine lines, reducing dark spots, or calming redness. Because you’re applying such a potent product on your face, it’s common to see positive results within a few weeks or even days of use. 

Moisturizers, on the other hand, are thicker and often heavier. Rather than soaking in quickly, many moisturizers sit on your skin and take their time to soak in deep. Now, you might be thinking - what’s the point having a dense moisturizer, when I can just get a concentrated shot from a serum? 

Serums are definitely the quick route to hydration, but they can’t effectively seal moisture in. The small molecules go deep to hydrate, but like water evaporates quickly, your skin can lose this moisture in a snap. A heavier moisturizer acts as a barrier for your skin to trap moisture and keep your complexion plump.

The main differences between a serum and a moisturizer are the layers of skin they effect, and the texture of the product. Long story short, a moisturizer is more dense, and treats the upper layers of your skin, helping to repair your skin barrier, while thinner serums treat deeper layers to hydrate and attack specific issues.

Can You Use Serums and Moisturizers Together?

It’s certainly not necessary to use both a serum and moisturizer, but they can be super effective together. It all depends on your skin type and the climate you live in. If you have an oily complexion, it’s possible you can get all the moisture you need from a serum. A serum feels light and airy, which is an answered prayer if you’re battling perpetually shiny skin. 

If you’ve got dry skin like me, keeping your skin hydrated and flake-free, especially in the winter, is a full-time job. Using a serum alongside a moisturizer ensures that the moisture goes down deep and gets sealed in. 

Maybe you’re somewhere in-between, and your skin fluxuates with the seasons. No sweat! Simply add in a serum when you need more moisture, and phase it out in more humid months, like summer. Many people only use a facial moisturizer, and that’s enough. If you’re looking to target skin issues or boost your glow, adding in a serum might do the trick!

So how do you use a facial serum with a moisturizer? Typically, a serum should go after cleansing and toning, but before moisturizing. Applying products from thinnest to thickest is a good rule of thumb. Your moisturizer should be the last step in your routine, to lock all those goodies into your skin. (Except during the day, when you should remember to apply sunblock!) 

Which Products are Best for You?

First, let’s talk about moisturizers. Not all conventional moisturizers are created equal. Your skin type and sensitivity should determine the formula you get. Oily skin benefits from the water-based gel moisturizers that are super light, while normal and dry skin types should opt for a thicker, cream-like moisturizer. 

Perfumed moisturizers can cause unneeded irritation to sensitive skin, so you might want to steer away from those if your skin has proven to be temperamental. 

Serums are a little tougher to narrow down because there are so many to choose from. You can simplify things by knowing which ingredients are best for each skin issue. Needing hydration? Hyaluronic acid will do the trick. 

Vitamin C fights dark spots and pigmentation, while retinol can stimulate collagen production for aging skin. If you have a sensitive, red complexion, niacinamide is a trusted ingredient to soothe stressed skin. 

One important note: if you struggle with eczema or rosacea, serums might not be for you. Their concentrated formulas can actually minimize your skin barrier, leading to more irritation and pain. Always patch test and introduce products slowly when switching up your skincare routine. 

All in all, serums and moisturizers both help get your skin dewy and hydrated, but their methods are very different. Like a protective bandage, a moisturizer seals your skin, preventing water loss. Serums are silent but deadly, going deep into your skin to attack problems, but they often don’t provide all the moisture you need. 

There! Another skincare mystery, demystified. However you introduce these products to your routine, we know they’ll be there for you through thick or thin. (Get it? It’s a skincare pun.)

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