Hair Serum vs. Hair Oil: Is There a Difference?

Most haircare products are pretty straightforward: Shampoo cleanses, conditioner moisturizes—you get the picture. Hair serums and hair oils, however, can be a bit trickier to figure out (specifically, determining the differences between hair oil and hair serum). While these two leave-in products may look similar—and sometimes even offer similar benefits—there are key differences between the two that you should be aware of before adding either into your routine. Ahead, we’ll explain how the two leave-in products stack up, reveal their benefits, and help you determine whether to use a hair serum vs. hair oil to achieve your haircare goals.

What Is Hair Serum?

Hair serum is a targeted hair care treatment designed to address specific hair concerns, such as dryness, frizz, dullness, split ends, or damage caused by heat styling or environmental factors. Similar to face serums, hair serums typically have a thin and slippery feel to them and often are fairly concentrated (which means a little goes a long way). They’re usually applied to damp hair before styling, though some can also be used on dry hair. If you have a hair serum you want to use and are unsure how to incorporate it into your routine, we suggest reading the directions on the product’s packaging.

What Is Hair Oil?

A hair oil is an oil-based hair treatment designed to nourish, moisturize, and smooth the hair (and, in some cases, the scalp). Common ingredients in hair oil formulas include argan oil, coconut oil, olive oil, and jojoba oil. These are all good oils for hair that can help address hair concerns without leaving the strands feeling limp or greasy.

However, the specific ingredients can vary depending on the formula and who it’s intended for. Hair oils for dry hair, for example, may contain additional ingredients designed to help hydrate and plump up the strands. Scalp oils, on the other hand, may contain exfoliating ingredients to help reduce build-up and debris. When choosing a formula, it’s important to consider your needs, preferences, and how you plan to incorporate the product into your routine.

What Is the Difference Between Hair Serum and Hair Oil?

While both hair serum and hair oil are often used to help replenish dry hair, they are not the same. Hair serums are ideal for reducing frizziness and providing better protection from heat damage and other forms of styling damage. They can also boost moisture and make hair softer and easier to style. As mentioned above, they’re typically applied to damp hair prior to styling.

Hair oils, on the other hand, can be applied to damp or dry hair. Different types of oils are used for different things, giving this product multiple uses and providing something for all hair types. For example, scalp oils—which are meant to be used on the scalp and the hair—can be used to help soothe a dry, itchy scalp.

Of course, the texture of the two products differs, too. Serums tend to be lightweight yet slippery, similar to a facial serum or thicker essence. Hair oils, unsurprisingly, have an oilier texture—though they, too, can be lightweight.

Who Should Use Hair Serums vs. Hair Oils?

Hair serums are ideal for those seeking smoother strands, an instant improvement in shininess, or protection against heat and environmental damage. They’re best for styling and addressing surface-level concerns without weighing hair down, making them great for fine to medium hair.

On the other hand, hair oils are rich, deeply moisturizing treatments that nourish and repair, working to nourish and replenish dry, depleted strands. They’re often more suitable for thick, coarse, or damaged hair in need of extra moisture or restoration.

It’s worth noting that you don’t have to choose between a hair serum and a hair oil—both can fit into your routine, so long as you use them properly. Many serums even contain oils in their formula for added nourishment and protection against dryness. These hybrid products allow you to reap the benefits of both styling staples, which can help streamline your haircare routine.

Our Favorite Hair Oils and Hair Serums

If you’re looking to level up your haircare routine, keep scrolling. We’re sharing details on our favorite hair oils and serums (and how to use them) below.

L’Oréal Paris EverPure Bond Repair Oil-in-Serum

This hair oil-in-serum is one of those products that offers the best of both worlds, and it’s well worth adding to your routine (particularly if you have damaged hair). The powerful formula, which contains a citric acid complex, helps moisturize and hydrate dry hair, boosts shine, and tames frizz. When used alongside the other products in the EverPure Bond system, it also helps strengthen brittle hair bonds damaged by excessive heat styling and chemical processing. Plus, it offers heat protection against temperatures up to 450 degrees Fahrenheit to help prevent future styling-related damage. The sulfate-free formula is color-safe and suitable for all hair types, so it can slot easily into any routine. Apply it prior to styling to help protect your tresses and boost hydration, or work a small amount through dry hair to smooth flyaways and give your strands a glossy, healthy-looking finish.

L’Oréal Paris Elvive Dream Lengths Frizz Killer Serum Leave-In

If you’re prone to frizz, consider adding this smoothing hair serum to your regular styling routine. It’s made with castor seed oil and cocoa butter and helps tame frizz and static for sleek-looking strands without leaving the hair feeling greasy. Plus, it doubles as a heat protectant, so you can apply it before blow-drying or heat-styling your hair without worrying about causing unnecessary damage.

L’Oréal Paris Elvive Hyaluron + Plump Moisture Plump Serum

Replenish dull, dry hair with this spray-on hair serum. The skincare-inspired formula, which contains a two percent hyaluronic acid complex, provides up to 72 hours of hydration and delivers an instant boost of moisture to help replump flat, dehydrated hair. Spritz it onto damp strands then comb through your mane to achieve bouncier, shinier-looking strands without any weigh-down or greasy residue

How To Use Hair Oil or Serum

There is no one-size-fits-all approach to using a hair oil or a serum—different products have different usage instructions. It’s always a good idea to read the directions on the packing for a clear understanding of how and when to use your chosen product.

That being said, a general rule of thumb is to start with a small amount of product and work it carefully throughout your mid-lengths and ends. Unless the product is specifically designed for use on the scalp, keep it clear from your roots—piling too much product onto your scalp can make your hair look greasy or limp. Comb or brush through your hair to ensure the product is evenly distributed, then reassess. If you think your strands could use a bit more smoothing or hydration, add more—but remember that less is more.

If you’re using other styling aids, you’ll also want to be mindful of when you use your product in your routine. This goes double for those with curls or coils following the LOC or LCO methods, as both can yield different results. If you’re still unsure how to use your product—or need guidance on the best way to layer products in your haircare routine—we suggest consulting with a haircare professional or chatting with an expert for personalized advice.

Next Up: What Is a Keratin Treatment for Hair?

Photo courtesy of L’Oréal Paris