Hair oils are the ultimate hair and scalp nourisher. And while they’re often a go-to for those with extremely damaged or dry hair, experts say that nearly all hair can benefit from using hair oils if appropriately applied. Why? Because of hair oil’s low molecular weight, it’s one of the few types of formulas that can truly penetrate the hair shaft.

“Your hair oil regimen depends on several factors, including your hair type, scalp condition, and personal preference,” says Marie Jhin, MD, a dermatologist in Silicon Valley, California. “Ultimately, finding the right balance and frequency of oil use is a personal journey, so experiment with different schedules and products to discover what works best for your hair—and always remember to use high-quality, natural oils and avoid overdoing it to maintain healthy, beautiful hair.”

Meet the expert

Here’s the ultimate guide to hair oils, their exact benefits, how to use them, and the products the pros swear by.

What Are Hair Oils?

“Hair oils are oil-based nourishing solutions that are applied topically to promote healthy hair growth, enhance shine, and combat common hair concerns,” says Jhin. Although hair oils vary in their ingredients, Jhin explains that they are all generally developed to deliver nutrients to the hair and promote scalp health. “A hair oil can be created as a blend of natural oils carefully formulated [together] to penetrate the hair shaft and provide deep hydration from root to tip,” she adds. Friend agrees, sharing that “a hair oil is a natural oil used to nourish, condition and improve the overall health of the hair and scalp,” she says.

Benefits of Oils for Hair

According to Carillo, “Hair oils can provide many benefits, including hydration, nourishment, and shine,” she says. “Plus, they can be used for styling, finishing, and treatment purposes.” Friend highlights that hair oils are rich in vitamins and minerals that nourish hair follicles and promote healthy hair growth. “They can help strengthen the hair and reduce breakage, add a healthy shine to hair, help reduce frizz and flyaways by smoothing the hair cuticle, and provide moisture. Plus, promote a healthy scalp environment for hair growth.”

Types of Hair Oils 

There’s a wide range of hair oils that provide various benefits to hair and scalp health:

Castor Oil

“Castor oil is rich in ricinoleic acid, which has anti-inflammatory properties and nourishes the scalp,” says Jhin.

Argan Oil

“Argan oil is packed with antioxidants, vitamins, and fatty acids that nourish the scalp and strengthen hair follicles,” shares Jhin. “It also helps improve hair elasticity and adds shine.” Another pro? “Argan oil helps to tame frizz and add shine,” she says.

Coconut Oil

“Coconut oil penetrates the hair shaft, reducing protein loss and strengthening the hair from within,” Jhin explains. “It also has antimicrobial properties that help keep the scalp healthy.” For very damaged hair, Carillo says coconut oil is key. “Coconut oil is known for its deep conditioning properties,” she says.

Peppermint Oil

“Peppermint oil has a cooling effect on the scalp and improves blood circulation, which can stimulate hair growth. It also has antimicrobial properties that help maintain a healthy scalp,” Jhin says.

Jojoba Oil

“Jojoba oil closely resembles the natural oils produced by the scalp, making it an excellent choice for balancing oil production and moisturizing the hair without leaving it greasy,” shares Friend.

Olive Oil

“Olive oil is rich in vitamins and antioxidants that help to nourish and strengthen the hair,” says Friend. “It can improve hair elasticity, reduce breakage, and add shine.”

Almond Oil

“Almond oil is lightweight and easily absorbed by the hair, making it an excellent choice for moisturizing and softening dry, damaged hair,” Friend explains.

Grapeseed Oil

Grapeseed oil is lightweight and easily absorbed, making it a great moisturizer and conditioner for the hair.

Rosemary Oil

“Rosemary oil is known for its stimulating properties, which promote blood circulation and nutrient delivery to the scalp.” shares Jhin.

How to Use Oils for Hair

“Using hair oils properly can make a significant difference in hair health,” says Friend, who suggests opting for the right oil for your hair type or specific concern such as frizz, dryness, or split ends. “When applying it to wet hair, I recommend using a small amount and distributing it to the mid-lengths and ends evenly, avoiding the roots; however, for dry hair, apply it to your palms, then rub it on the ends only and add more if needed.”

Hair oils are particularly beneficial when used as an overnight treatment for hair that is dry, over-processed, or damaged because it allows ample time for the oil to penetrate the hair shaft. “Regular use of hair oils can improve hair texture and manageability,” Friend says. Jhin explains that deciding to apply a hair oil treatment to wet or dry hair depends on personal preference and the end result. “For example, applying hair oil to damp hair can help seal in moisture, while using hair oil on dry hair can provide a smoother finish,” she says.

Jhin also recommends sectioning hair for a targeted application method. “Divide your hair into sections, which allows you to target both the scalp and the lengths of your hair and ensure even distribution of the oil,” she explains. She also recommends that clients use hair oil as a pre-shampoo treatment or as a leave-in nourisher. “If you’re using the oil as a leave-in treatment, you don’t need to rinse it out; simply style as usual. But if you’re using it as a pre-shampoo treatment, wash your hair with a gentle shampoo one to two times to remove the oil.” Some hair types—especially those that are thick, dry, coarse, unruly, or excessively damaged—can benefit from using a hair oil treatment one to two times per week.

When to Avoid Oil for Hair

“There are certain situations where it's best to avoid using oils on your hair,” says Jhin. “Using heavy oils can weigh down fine or thin hair, making it appear greasy and flat.” However, she explains that instead of ditching oils entirely, opt for a lighter oil or oil-based products specifically formulated for fine hair. “If you already have an oily scalp, applying additional oil can exacerbate the problem, making your hair more greasy,” she says. “In this case, try using oil-free or lightweight products that don’t weigh down your hair or make your scalp feel oily.”

Because it is essential that hair oils penetrate the hair shaft to be beneficial, pros recommend not applying hair oil to strands that are coated in products that may act as a barrier. “If you have buildup in your hair, use a clarifying shampoo once or twice a week,” says Jhin. “A hair oil treatment will be most effective on a clean hair and scalp without other products interfering with its benefits.”

If you have a scalp condition, such as seborrheic dermatitis, scalp psoriasis, or scalp acne, it may be best to avoid oils for hair. Consult your dermatologist or doctor to decide the best scalp regimen for you. “There are certain kinds of fungus that feed on the presence of oils, which can lead to an increase in flaking and skin inflammation,” says Carillo. Also, if you have allergies to certain ingredients or oils, avoid those as well—and be sure to check the label, as hair oils are often a blend of multiple ingredients.

Frequently Asked Questions

• What is the best oil for your hair?

  “When it comes to hair care, the molecular weight of oil refers to the size of the oil’s molecules,” notes Friend. “Oils with a low molecular weight can penetrate the hair shaft more deeply, nourishing and moisturizing it from within—coconut oil, jojoba oil, argan oil, sweet almond oil, and grapeseed oil are some examples of oils with low molecular weights that can improve hair health.”

• How often should you oil your hair?

  How frequently hair oils should be used depends on several factors. “It depends on hair type, scalp condition, and personal preference,” says Friend. “For most, using oil on the hair one to three times a week is sufficient to reap the benefits without causing buildup or greasiness. However, dry or damaged hair may benefit from more frequent use, while oily hair may need it to be less often.”

• What oils should you avoid putting in your hair?

  “I recommend never applying kitchen oils to your hair,” says Carillo. “These types of oils are typically extracted conventionally, while oils in hair products are crafted in labs by chemists using controlled heating and precise formulation for superior performance, penetrating the hair cuticle effectively due to their specialized molecular structure.”

• Can hair oils aid in hair growth?

  “Overall, hair oils have moisturizing, nourishing, and stimulating properties, providing essential nutrients such as vitamins, minerals, and fatty acids that can help create an optimal environment for hair growth,” says Friend. But there are some hair oils that outperform others in this category: “Castor oil and coconut oil have properties that stimulate circulation to the scalp to promote better blood flow and nutrient delivery to the hair follicles,” she says. “Rosemary and peppermint oil stimulate hair follicles, encouraging them to enter the growth phase of the hair cycle more quickly.”