Rosemary Oil for Hair: What Research Shows and How to Use It

Rosemary essential oil is concentrated. Mix it into a carrier oil before it touches skin, keep it away from the eyes and out of reach of children, and do not swallow it. Doctors have linked rosemary and several other camphor- and cineole-rich oils to seizures, so skip it if you have epilepsy unless your doctor agrees.

What is rosemary oil?

Rosemary is the woody, needle-leaved herb native to the Mediterranean. Botanists now file it under the sage genus as Salvia rosmarinus; the older name Rosmarinus officinalis is still printed on most bottles and in most studies (Kew's Plants of the World Online).

The essential oil is made by passing steam through the leaves and flowering tops, then collecting the aromatic fraction that separates out. Its chemistry varies from farm to farm. When chemists analyzed oils from six countries, the leading compounds were alpha-pinene (13.5% to 37.7%), 1,8-cineole (16.1% to 29.3%) and smaller amounts of verbenone, borneol and camphor, and they sorted rosemary oils worldwide into at least five chemical types (Satyal et al., Foods, 2017). That spread is one reason two bottles can smell a little different.

So what is rosemary oil used for (¿para qué sirve el aceite de romero?)? Three things, mainly: scalp and hair care, aromatherapy, and as a natural flavoring in food manufacturing, where the FDA counts rosemary oil among flavorings considered safe when used as intended (21 CFR 182.20). That food listing covers tiny flavoring amounts, not spoonfuls of oil.

Rosemary oil for hair growth: what the research shows

The study everyone cites is Panahi and colleagues (SKINmed, 2015). One hundred adults with androgenetic alopecia (pattern hair loss) were randomly assigned to rosemary oil or 2% minoxidil for six months, 50 per group. Key findings:

• At three months, neither group had a meaningful change in hair count.
• At six months, both groups had gained hair compared with where they started, and the difference between the two groups was not significant.
• Scalp itching went up in both groups, but it was more common with minoxidil at both check-ins.

Before you read too much into it, notice the limits. It is one trial of 100 people. There was no placebo group, so we cannot say how much of the gain either product caused on its own. The published abstract does not spell out the strength of the rosemary preparation, which makes it hard to copy at home. And 2% minoxidil is the lower-strength version of that drug.

Reviews since then land in the same place. A 2024 review notes that finasteride and minoxidil remain the only FDA-approved drugs for pattern hair loss and that herbal options, rosemary oil included, need more research before anyone can call them proven (Bin Rubaian et al., Clinical, Cosmetic and Investigational Dermatology). A dermatology review of hair oils popular in the Black community adds that most of the supporting work so far has been done in mice (Dinkins et al., International Journal of Dermatology, 2023).

There is one older human trial worth knowing about, in a different condition. In alopecia areata, an autoimmune type of patchy hair loss, 86 patients massaged their scalps every day for seven months. The active group used thyme, rosemary, lavender and cedarwood oils mixed into jojoba and grapeseed oil; the control group used the carrier oils alone. Improvement showed up in 44% of the essential oil group versus 15% of controls (Hay et al., Archives of Dermatology, 1998). Because four oils were blended, the trial cannot tell us how much rosemary itself contributed.

Bottom line: rosemary oil is studied for hair, with one encouraging head-to-head trial. It is not a proven treatment, and results in the trial took about six months to appear.

How to use rosemary oil on your scalp

First decide which kind of product you have, because "rosemary oil" on a label can mean three different things.

If you are using the essential oil, a simple routine looks like this:

1. Dilute. Blend the essential oil into a carrier oil (jojoba, almond, olive or castor) using the dilution on your bottle's label. Essential oils are meant to go on skin in diluted form (NCI; NCCIH).
2. Patch test. Dab a little of the mix on your inner forearm and wait a day. Redness, itching or bumps mean stop.
3. Massage it in. Part the hair and work a small amount into the scalp with your fingertips for a few minutes. The trials above used regular, repeated application, often daily.
4. Wash it out with your usual shampoo when you are ready. Nobody has studied whether leaving it in overnight works better.
5. Give it time. In the 2015 trial, hair counts had not budged at three months; changes appeared by six.

A ready-made scalp blend saves the mixing step. Follow its directions, since the dilution has been done for you.

Other uses: aroma, memory and cooking

Aromatherapy. Rosemary has a fresh, camphor-like smell that many people find wakes them up. NCCIH notes that essential oils are usually inhaled or applied diluted, and that rigorous research on aromatherapy is limited overall.

Memory and focus. In a small Northumbria University study, 20 healthy volunteers did math and attention tasks in a cubicle scented with rosemary. People with higher blood levels of 1,8-cineole afterward tended to perform faster and more accurately (Moss and Oliver, Therapeutic Advances in Psychopharmacology, 2012). It was a correlation in a small group without a comparison room, so it hints at something rather than proving it.

Cooking. Dried and fresh rosemary are classic kitchen herbs, and the FDA lists rosemary among spices that are generally recognized as safe (21 CFR 182.10). Cook with the leaves, not the essential oil.

Rosemary oil side effects and who should be careful

• Skin. Allergic reactions and irritation can happen, especially when an essential oil stays on skin for a long time (NCI). Dilute and patch test.
• Old oil. As essential oils age and oxidize, compounds such as alpha-pinene can form products that are more likely to sensitize skin, so keep the bottle capped in a cool, dark spot (Sharmeen et al., Molecules, 2021).
• Seizures. A Swiss neurology team reviewed the literature and listed rosemary among eleven plant oils known to provoke seizures, blaming reactive compounds such as camphor and cineole, and reported three cases, one in a child (Burkhard et al., Journal of Neurology, 1999). If you have epilepsy, talk to your doctor first.
• Children. Keep essential oils out of their reach and ask a pediatrician before using any on a child.
• Swallowing. NCI advises against swallowing essential oils in large amounts.
• Pregnancy and breastfeeding. Check with your midwife or doctor before using rosemary essential oil.
• Hair loss itself. Sudden shedding, bald patches or scalp pain deserve a visit to a dermatologist, because hair loss has many causes and some need medical treatment.

Find it at William's

We carry several rosemary oils, so you can pick the form that fits your routine:

• Now rosemary oil, 1 oz: pure rosemary essential oil, steam-distilled from the tops of the plant. Mix it into your own carrier oil or shampoo.
• Now organic rosemary oil, 1 oz: the certified organic version, distilled from the flowering tops and leaves.
• Earth's Care rosemary oil, 1 oz: pure rosemary essential oil packaged for diffusers and aromatherapy.
• Sky Organics organic rosemary Strong Roots oil, 2 oz: a certified organic scalp oil blend made for hair. Read the label for its ingredients and directions.

For cooking, we carry Starwest organic rosemary leaf powder, sold by weight. We don't currently list a plain rosemary-infused oil online; call the store to check what's on the shelf. Pairing rosemary with a carrier? Our guides to Jamaican black castor oil and batana oil cover two popular hair oils, and the herbal oils A to Z guide explains sage, bergamot and other oils on our shelves.

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