Does Rosemary Oil for Hair Growth Really Work?

Thinning hair can sneak up on you, but once you've noticed it, it can be hard to pay attention to anything else. If you've become consumed with trying to restore your hair growth, there's no need to run to the heavy-duty formulas. In fact, some plant-based ingredients might just be your best bet.

According to both internet folklore and legit research, rosemary oil may play a role in encouraging hair growth and can be a worthwhile first step for mild hair thinning. Here are the details, plus how to start incorporating it into your everyday routine.

Does Rosemary Oil Grow Hair?

Rosemary oil is an essential oil known for its anti-inflammatory properties. Although little research exists on rosemary oil for hair growth, a 2015 study published in the journal SkinMED revealed some interesting findings. For the study, 100 people with androgenetic alopecia (a genetic hair loss condition) were split into two groups. One group applied rosemary oil to their scalps over six months, the other applied a 2 percent minoxidil treatment during the same timeframe. (Minoxidil is a common ingredient in products for hair loss, which is said to send hairs from their "resting" phase into their "growing" phase faster. It's available topically over the counter or orally by prescription.)

At the six-month mark, the two treatments seemed to work equally well: Both groups showed a significant increase in hair count, and there wasn't a sizeable difference in hair count between the two groups. What's more, rosemary oil may have an advantage compared to minoxidil treatments when it comes to side effects. While both groups reported increased scalp itching during the study, scalp itching was more common in the minoxidil group.

Although more research is warranted, the takeaway is that "rosemary oil can help promote hair growth in some individuals with age-related hair loss, such as androgenetic alopecia," says James Y. Wang, M.D. dermatologist and founder of Metropolis Dermatology.

How? Scientists aren't 100 percent sure yet, but they have theories. "It is not entirely clear what the mechanism is, but [rosemary oil] is thought to block DHT, a form of testosterone, from interacting with receptors on the hair follicles," explains Dr. Wang. "This prevents the shrinking of the hair follicles [provoked by DHT]." (High DHT levels can cause hair follicles to shrink and eventually stop sprouting hair altogether.)

Note: Even if you don't have androgenetic alopecia, you may still benefit from rosemary oil for hair growth. "Other forms of hair loss triggered by irritation, hormonal supplements, and overall weak hair follicles could potentially be helped by using rosemary oil due to the oil's purported ability to mildly improve circulation and decrease inflammation," says Dr. Wang. Boosting circulation increases the delivery of oxygen to the scalp, which in turn can encourage hair growth. Meanwhile, inflammation can cause hair to shed before it's reached the end of its growth cycle.

Are There Downsides to Using Rosemary Oil for Hair Growth?

If you have a temperamental scalp, you probably took note of that scalp itch detail of the study. Oils can present issues for some people, so if you're experiencing irritation of the scalp, such as dandruff, you should try to tackle that issue first before starting rosemary oil, says Dr. Wang. He recommends seeing a dermatologist, since "all oils can cause some level of irritation or worsen scalp dandruff."

When it comes to using rosemary oil vs. minoxidil for hair loss, Dr. Wang says it's a matter of personal preference. "Many people prefer a natural route to start their hair loss treatment," he says. "Minoxidil can be very effective, but not everyone likes the way it feels on the scalp. It can also induce irritation and an initial shedding phase, which may be undesirable for a lot of people," continues Dr. Wang.

How to Use Rosemary Oil for Hair Growth

If you do want to use rosemary oil for hair growth, Dr. Wang has a few pointers. First, you should use rosemary oil after you wash your hair. "For example, if you wash your hair twice per week, use it twice per week after the shower," he says. You don't have to rinse out the oil after applying it, but if you do choose to rinse it out, make sure you let it sit on your scalp for at least 10 minutes first, advises Dr. Wang.

You want to be pretty sparing with the oil since excess oil on the scalp can lead to "overall irritation and inflammation," adds Dr. Wang. To avoid overdoing it while still getting the effects, you only need to add about five drops of pure oil directly to your scalp, he says. Alternatively, you can add the drops to your regular shampoo or other hair products that you massage directly into your scalp.

If you want to try to encourage hair growth with rosemary oil, here are a few products with the essential oil that you can add to your hair routine.