Beauty Hair Hair Oil vs. Hair Serum: Which One Is Better for You? Let's get to the bottom of these two popular products. By Erin Lukas Erin Lukas Instagram Twitter Erin is a Brooklyn-based beauty editor and has been with InStyle since 2016. She covers all facets of beauty for the site. InStyle's editorial guidelines Published on July 8, 2022 @ 02:53PM Pin Share Tweet Email Photo: Getty Images A hair oil and hair serum are easy to mix up as they look so similar. However, experiencing both products in your hair will bring you to the conclusion that they're not the same. Oils tend to be absorbed by the hair, while serums typically feel like they're coating strands. Just like the oils and serums you apply to your face, the ones for your hair serve different purposes and can be a beneficial addition to your haircare routine depending on your hair texture and concerns. So, should you use a hair oil or hair serum? We turned to two experts to find out what both products do, who should use them, and how to use them. The Best Hot Oil Treatments You Didn't Know Your Natural Hair Needed What Is a Hair Oil? Like the name implies, a hair oil is an oil-based product. Isfahan Chambers-Harris, a trichologist, Ph.D. Scientist, and founder Alodia Haircare, says that the formula typically consists of at least two carrier oils (like avocado, coconut, and almond) and essential oils (like lavender and lemongrass). An oil offers a handful of benefits for the hair and scalp, including scalp stimulation, maintaining moisture within the strand, and aiding in length retention. In turn, the oil can help hair feel softer and appear shinier. 01 of 06 Alodia Nourish & Grow Healthy Hair and Scalp Oil Courtesy $16; amazon.com With avocado and rosemary oils, this moisturizing treatment nourishes the scalp and hair follicles to soothe dryness and support growth. 02 of 06 Ceremonia Aceite de Moska Courtesy $25; credobeauty.com In addition to nourishing hair, Ceremonia's oil works to rebalance the scalp by removing product buildup and excess sebum. 03 of 06 Fable & Mane HoliRoots Pre-wash Hair Treatment Oil Courtesy $34; sephora.com Use Fable & Mane's pre-shampoo oil treatment inspired by ancient Indian hair rituals to strengthen and repair damaged or dry hair. What Is a Hair Serum? A hair serum is a lightweight product that covers the outer surface of the hair, acting as a seal or protectant. Dr. Chambers-Harris says that hair serums typically contain silicones or silicone-like substances that sit on top of the hair strand. If you're prone to frizz or have chemically-treated hair, you may benefit from adding a hair serum to your routine. "Hair serums have benefits such as taming frizz and flyaways, adding shine, shielding against humidity, softening your strands, and helping with damage caused by chemically damaged hair or hair that has been over-styled with heat tools," shares Deaundra Metzger, an Atlanta-based celebrity hairstylist. 04 of 06 Olaplex No. 9 Bond Protector Nourishing Hair Serum Courtesy $30; sephora.com Olaplex's serum is designed to protect hair that's been weakened by chemical treatments from future damage. It doubles as a styling product that smooths frizz and minimizes tangles. 05 of 06 Mizani Press Agent Smoothing, Frizz Control Blow Dry Styling Serum Courtesy $22; sephora.com If you regularly use hot tools, make Mizani's heat protectant serum part of your styling routine. It shields hair against temperatures up to 450 degrees Fahrenheit, plus moisturizes for a soft, glossy finish. 06 of 06 Dr. Barbara Sturm Balancing Scalp Serum Courtesy $100; drsturm.com Dry, itchy, flaky scalps will benefit from Dr. Sturm's balancing serum. It works to reduce inflammation with a blend of plant-based ingredients such as Japanese camellia, brown and green algae, and lavender. What's the Difference Between a Hair Oil and Hair Serum? The major difference is the products' ability to penetrate the hair strand. "Hair oil conditions and nourishes hair, directly impacting overall hair health, but no such impact is seen with the use of hair serums, says Metzger. "Hair oil penetrates deep into the hair shaft to nourish hair from within, whereas hair serum merely sits on the surface and forms a layer." It's best to think of a hair serum as a shield or armor for the hair. For example, Dr. Chambers-Harris says if you're styling your hair with hot tools, prep the hair with a silicone-based serum for heat protection. The 10 Best Oils to Use for Every Hair Situation Who Should Use Hair Oil? All hair types and textures can use a hair oil. However, how you use an oil will vary. "Drier hair types such as textured hair tolerate oils well," Dr. Chambers-Harris says. "Straighter hair types can use oils but should use them before shampooing." Rinsing the oil out with shampoo will still deliver the benefits without weighing down straight and/or fine hair. Who Should Use Hair Serum? They're also a universal product — just be aware of the ingredients, specifically if you have curly/textured hair. "If you are wearing your hair in its curly/textured state most of the time, you should be careful with using silicone-based serums because they can cause buildup over time and block moisture from getting in, leaving your hair feeling and looking dry — particularly if you are using a non-sulfate shampoo to wash your hair," explains Dr. Chambers-Harris. VIDEO: The Best Hot Oil Treatments You Didn't Know Your Natural Hair Needed What's the Best Way to Use Hair Oils and Hair Serums? There are a plethora of ways to utilize a hair oil in your routine based on your hair type and its needs. "You can oil the hair and scalp before shampoo, you can use as a hot oil conditioning treatment, and you can use them as a 'sealant' to seal in the cream based hair conditioner that you used for styling," Dr. Chambers-Harris says. How much product you use will vary by hair length. "If you're rocking a shorter style, then one to two small pumps are enough, while longer styles may find three to four pumps more appropriate," says Metzger. Again, it's important to note that if you have straight hair, an oil is best used as a pre-shampoo treatment to prevent weighing hair down. As for hair serums, when you use one in your routine will depend on its purpose. When you're applying it, Metzger suggests going by hair length. "A single pump of serum will suffice for mid-length hair, while long hair may require a bit more," the stylist says.