Rosemary Oil for Hair Growth: What the Evidence Shows

Short answer: Rosemary oil may help some people with pattern hair loss, but the evidence is thin. Its reputation rests mostly on one 2015 trial of 100 people that found rosemary oil and 2% minoxidil worked about equally after six months. S01 That trial had no placebo group, and reviews say more robust, longer-term research is needed. S03 S04 If you try it, dilute it, massage it into your scalp a few times a week and give it about six months. S08

Rosemary oil is one of the most talked-about natural hair growth remedies. Here's what the studies actually tested, how to use it and when to see a dermatologist instead. For how it stacks up against other oils, see our hair growth oils comparison.

What the research shows

The 2015 rosemary vs minoxidil trial

Most claims about rosemary oil trace back to a single randomized trial. Researchers assigned 100 people with androgenetic alopecia, or pattern hair loss, to use either rosemary oil or 2% minoxidil for six months. S01 They measured hair counts with standardized photos. S01

What they found: S01

• At three months, neither group had a significant change in hair count.
• At six months, both groups had significantly more hair than at the start.
• There was no significant difference between the two groups at either point.
• Scalp itching rose in both groups, but it was more common with minoxidil.

That sounds encouraging, but there are real limits. There was no placebo group, so we can't tell how much of the change was due to either treatment. S01 It was one study with 50 people per group, and it compared rosemary only with the 2% strength of minoxidil. S01

Lab and animal studies

A 2013 study found that rosemary leaf extract applied to mice improved hair regrowth after it had been blocked with testosterone. S02 In lab tests, the extract blocked testosterone 5-alpha-reductase. Blocking that enzyme is a well-recognized strategy for treating pattern hair loss. S02 In pattern hair loss, the hormone DHT binds to receptors in the scalp and shrinks hair follicles. S03 This gives a possible explanation for how rosemary might work, but mouse and lab results don't always carry over to people.

What reviews conclude

A 2025 review looked at 13 controlled trials of non-prescription hair loss products, including rosemary oil. S04 It found improvements in at least one measure and few side effects, but said more robust, long-term data are needed. S04 A 2024 review noted that the only FDA-approved medicines for pattern hair loss are finasteride and minoxidil. S03 It said more research is needed to establish how well natural remedies like rosemary oil work. S03

Rosemary for alopecia areata

A 1998 trial tested a blend of thyme, rosemary, lavender and cedarwood oils in people with alopecia areata, an autoimmune cause of patchy hair loss. S05 After seven months of daily scalp massage, 44% of the essential oil group improved, compared with 15% of those using carrier oils alone. S05 Because it was a blend, the study can't tell us what rosemary did on its own.

How to use rosemary oil for hair

Cleveland Clinic dermatologist Shilpi Khetarpal, MD, offers these tips: S08

1. Dilute it. Mix rosemary oil with a carrier oil such as coconut or jojoba oil to lower the risk of irritation.
2. Work it into your scalp. Coating the lengths of your hair won't help. Focus on massaging it into the scalp.
3. Use only a few drops. You can also add a few drops to fragrance-free shampoos, conditioners or hair masks. Fragrance can raise the risk of irritation.
4. Leave it on. Leave it on your scalp for at least a few hours. Dr. Khetarpal suggests applying it at night and washing it out in the morning.
5. Be consistent. She says you'll likely need to use it two or three times a week for six months to see meaningful improvement.

Patch test first. Try it on a small area of your scalp before using it all over, especially if you have fine hair or atopic dermatitis. S08 Our guide on how to patch test skincare walks through the steps.

How long does it take?

Expect to wait months, not weeks. In the 2015 trial, neither treatment changed hair counts at three months, and gains showed up at six months. S01 That fits Dr. Khetarpal's advice to give it about six months. S08 For comparison, the American Academy of Dermatology says minoxidil usually takes 6 to 12 months to show results. S09

Set realistic expectations. Dr. Khetarpal says rosemary oil may help a bit, especially if your hair loss is just starting, but it may not work for everyone. S08

Side effects and who should skip it

Rosemary oil is generally considered safe on the scalp, but it can cause problems. S08

• Irritation from overuse. Using too much can cause scalp irritation, redness, burning, inflammation and damaged hair follicles. S08 Stop using it and see a dermatologist if you get irritation. S08
• Allergic reactions. Published case reports show rosemary can cause allergic contact dermatitis. S06 Researchers think these reactions are uncommon but may be underdiagnosed. S06 Two reported cases involved cross-reactions between rosemary and thyme, so people who react to thyme may also react to rosemary. S06
• Pregnancy and breastfeeding. Cleveland Clinic says it isn't recommended if you're pregnant or breastfeeding. S08

Does rosemary oil cause grey hair?

There's no good evidence that it does. A 2025 online survey of 994 people in Saudi Arabia looked at rosemary use and hair greying. S07 About 23% of rosemary users reported greying, but in the full analysis, using rosemary oil was linked to a lower chance of greying. S07 It was a self-reported survey, so it can't show cause and effect in either direction. S07

Rosemary oil vs other options

If you want to compare rosemary oil with other popular remedies, see our guides to castor oil for hair, rice water for hair and biotin for hair growth. For daily care, see our picks for shampoo for thinning hair.

The AAD notes that minoxidil can help early hair loss but can't regrow a full head of hair. S09 It works best alongside another treatment, and you need to keep using it to keep the results. S09

The bottom line

Rosemary oil is a low-cost option with early, promising evidence for pattern hair loss and few reported side effects in trials. S01 S04 But the human evidence comes down to a handful of small studies, and the best-known one had no placebo group. S01 S03 If you try it, think of it as an experiment: use it consistently for six months, watch your scalp for irritation and track your results with photos taken in the same light. S08

When to see a dermatologist

Hair loss has many causes, and the right treatment depends on the cause. S09 The AAD says no single treatment works for everyone. S09 Sometimes hair grows back on its own, such as after having a baby, a major illness, cancer treatment or losing 20 pounds or more. S09 A board-certified dermatologist can find the cause and tell you whether treatment makes sense. S09 See one if your hair loss is sudden, patchy or getting worse, or if your scalp is itchy, red or scaly.

Frequently asked questions

Does rosemary oil really grow hair?

It may help some people with pattern hair loss. One 2015 trial found rosemary oil and 2% minoxidil increased hair counts by similar amounts after six months, but there was no placebo group. Reviews say stronger, longer-term studies are needed.

Is rosemary oil as good as minoxidil?

In one trial of 100 people, rosemary oil and 2% minoxidil showed no significant difference in hair count at six months. That's a single study without a placebo group. Minoxidil is FDA-approved for pattern hair loss, and rosemary oil isn't.

How often should I use rosemary oil on my hair?

A Cleveland Clinic dermatologist suggests two or three times a week for about six months. Dilute a few drops in a carrier oil, massage it into your scalp and leave it on for a few hours or overnight.

Can I put rosemary oil directly on my scalp?

It's best to dilute it first in a carrier oil such as coconut or jojoba oil. Use only a few drops, and patch test a small area of your scalp before using it all over. Overuse can cause irritation, redness and burning.

Who shouldn't use rosemary oil?

Cleveland Clinic says it isn't recommended if you're pregnant or breastfeeding. Skip it or stop if it irritates your scalp. People who've reacted to thyme may also react to rosemary, since cross-reactions have been reported.