Rosemary (Rosmarinus officinalis) is an evergreen shrub with needle-like leaves and a woody aroma. Though best known as a food seasoning, it is one of the most popular aromatic and medicinal plants worldwide. Rosemary’s essential oil — which holds the plant’s core components, or essence — is extracted and sold in small bottles. Despite its name, it is not a true oil, as it doesn’t contain fat. Due to rosemary oil’s use in folk medicine, many scientists are now testing its potential health benefits. Though most of this research is just beginning, it supports some traditional uses of the oil and illustrates possible new uses.

Here are potential benefits and uses of rosemary essential oil.

1. May Improve Brain Function

In ancient Greece and Rome, rosemary was thought to strengthen memory.

Research indicates that inhaling rosemary oil helps prevent the breakdown of acetylcholine, a brain chemical important for thinking, concentration and memory.

When 20 young adults were asked math questions in a small room diffused with rosemary oil, their speed and accuracy increased in direct proportion to the duration the oil was diffused.

Additionally, their blood levels of certain rosemary compounds likewise increased — illustrating that rosemary can enter your body through breathing alone.

Similarly, nursing students who breathed rosemary oil while taking a test reported increased concentration and information recall compared to breathing lavender oil or no essential oil at all.

Other research suggests that breathing rosemary and other essential oils may improve brain function in older adults with dementia, including those with Alzheimer’s disease.

Keep in mind that more research is needed.

Breathing rosemary oil may help you focus and remember information. It may also aid your memory as you age, but more research is needed.

2. Stimulates Hair Growth

One of the most common types of hair loss is androgenetic alopecia, better known as male pattern baldness, though it can also affect females.

Rosemary oil treats androgenetic alopecia by preventing a byproduct of testosterone from attacking your hair follicles, which is the cause of this condition.

When men with androgenetic alopecia massaged diluted rosemary oil into their scalp twice daily for six months, they experienced the same increase in hair thickness as those who used minoxidil (Rogaine), a common hair regrowth remedy.

Additionally, those who used the rosemary oil reported less scalp itching compared to minoxidil, which suggests that rosemary may be more tolerable.

Other research indicates that rosemary oil may fight patchy hair loss, or alopecia areata, which affects up to half the population below age 21 and about 20% of people above 40.

When people with alopecia areata rubbed a rosemary essential oil blend into their scalp each day for seven months, 44% showed improvement in their hair loss compared to only 15% in the control group, who used the neutral oils jojoba and grapeseed.

Rosemary oil may combat certain types of hair loss, including male pattern baldness and patchy hair loss.

3. May Help Relieve Pain

In folk medicine, rosemary is utilized as a mild pain reliever.

In a two-week study, stroke survivors with shoulder pain who received a rosemary oil blend with acupressure for 20 minutes twice daily experienced a 30% reduction in pain. Those who received only acupressure had a 15% reduction in pain.

Additionally, an animal study determined that rosemary oil was slightly more effective for pain than acetaminophen, a common over-the-counter pain medication.

Rosemary oil is known in folk medicine as a pain reliever. Preliminary studies support its pain relief benefits and suggest that it may be more effective than acetaminophen.

4. Repels Certain Bugs

For deterring harmful insects that may bite you or infest your garden, consider rosemary oil as a natural alternative to chemical products.

When a rosemary-oil-based pesticide, EcoTrol, was sprayed on greenhouse tomato plants, it reduced the population of two-spotted spider mites by 52% without harming the plants.

Rosemary also helps repel certain blood-sucking insects that can spread harmful viruses and bacteria.

When rosemary oil was measured against 11 other essential oils, it had the longest repellent effect on Aedes aegypti mosquitoes, which spread the Zika virus. A dilution of 12.5% rosemary oil repelled 100% of the mosquitoes for 90 minutes.

Additionally, a spray containing 10% of rosemary oil was similarly effective as the chemical insecticide bifenthrin for controlling the spread of black-legged ticks — which harbor Lyme disease.

Rosemary oil is used in natural pesticides to kill certain insects. Additionally, the oil helps repel some blood-sucking insects, such as particular mosquitoes and ticks.

5. May Eases Stress

Many factors can cause stress — including school tests. Inhaling rosemary oil may help reduce test anxiety.

When nursing students breathed rosemary oil from an inhaler before and during test time, their pulse decreased by about 9% — while no significant change occurred without rosemary oil.

Because increased pulse rates reflect short-term stress and anxiety, rosemary oil may naturally reduce stress.

Additionally, when 22 young adults sniffed rosemary oil for 5 minutes, their saliva had 23% lower levels of the stress hormone cortisol compared to those who smelled a non-aromatic compound.

Increased cortisol levels can suppress your immune system, contribute to insomnia and cause mood swings, among other potential problems.

Simply smelling rosemary oil may ease your stress levels in situations like exam taking. Rosemary may reduce levels of cortisol, a hormone that can have harmful effects on your body.

6. May Increase Circulation

Poor circulation is a common complaint. You may notice it most in your hands and feet.

If you experience cold fingers and toes — even in relatively warm temperatures — rosemary oil is worth considering.

In one study, a woman with Raynaud’s disease — which impairs circulation — massaged her hands with a rosemary oil blend, finding that it helped warm her fingers more than a neutral oil. These effects were confirmed by thermal imaging.

If you have Raynaud’s disease, blood vessels in your fingers and toes constrict when you’re cold or stressed, causing them to lose their color and turn cold.

Rosemary oil may help by expanding your blood vessels, thereby warming your blood so that it reaches your fingers and toes more easily.

More research is needed to confirm these effects — but rosemary may prove a worthwhile, low-cost experiment.

If you experience cold fingers or toes, massaging with rosemary oil may help warm them. 

7. May Help Perk You Up

Rosemary oil is commonly used for mental strain and fatigue in folk medicine.

When 20 healthy young adults inhaled rosemary oil, they reported feeling about 30% more mentally refreshed and about 25% less drowsy compared to smelling a placebo oil.

This increase in alertness corresponded to changes in brain waves and increases in heart rate, breathing and blood pressure.

Applying diluted rosemary oil to your skin may provide similar benefits, as it can reach your brain via this route.

In one study, applying diluted rosemary oil to the skin caused 35 healthy people to feel significantly more attentive, alert, energetic and cheerful after 20 minutes than when using a placebo oil.

Still, more research in this area is needed to confirm these results.

A few small studies suggest that rosemary oil may boost attention, alertness, energy and mood. Yet, more research is warranted.

8. May Reduce Joint Inflammation.

Preliminary evidence suggests that rosemary oil may help reduce tissue inflammation that can lead to swelling, pain and stiffness.

It may do so by stemming the migration of white blood cells to injured tissues to release inflammatory chemicals.

When people with rheumatoid arthritis were given 15-minute knee massages using a rosemary oil blend three times weekly, they had a 50% decrease in inflammatory knee pain in two weeks, compared to a 12% decrease in those not given the oil.

Rheumatoid arthritis is an autoimmune condition in which your body’s own immune system attacks tissues, such as knees and other joints, injuring the joint lining and causing inflammation.

Applying diluted rosemary oil topically may help lower inflammation in injuries and rheumatoid arthritis. However, more research is needed to confirm this.

9. Your Health

Scientists are investigating several other uses of rosemary oil, but human studies are lacking.

Test-tube studies aren’t equivalent to human research that tests essential oils via inhalation or topical application, which are accepted uses for people.

Additionally, some animal studies have administered rosemary oil orally, but this is not recommended. Essential oils should not be swallowed.

Still, rosemary oil may prove useful for:

Cancer: Rosemary oil has antioxidant and anti-inflammatory effects, which test-tube studies suggest may fight cancer cells.

Liver and digestive health: Animal studies indicate that rosemary oil may stimulate the release of bile, which is important in fat digestion, and activate your own antioxidant defense mechanisms to protect your liver.

Food poisoning: Rosemary oil can help inhibit the growth of certain strains of bacteria that cause food poisoning. This requires using precise, very small amounts of food-grade oil. Don’t experiment with this at home.

Antibiotic side effects: Rosemary and other essential oils may increase the effectiveness of certain antibiotics. This may allow for a lower dose of these drugs, which could reduce side.

Antibiotic resistance: Rosemary and other essential oils may weaken the cell walls of antibiotic-resistant bacteria — not only damaging them but also enabling antibiotics to enter.

Potential future uses of rosemary oil include preventing cancer and food poisoning, as well as supporting liver and digestive health. Yet, no human studies on these effects have been conducted.

Though some manufacturers claim it’s safe to swallow or consume their essential oils, there isn’t scientific evidence supporting this — especially over the long term. Essential oils should never be swallowed.

Here are a few easy guidelines for inhalation or topical use of rosemary oil.

Inhaling

The simplest way to inhale rosemary oil is to open the bottle and breathe in. Alternately, you can place a few drops on a cloth or tissue and hold it near your face.

Many people use aromatherapy diffusers, which distribute the essential oil into the surrounding air.

In general, avoid placing a diffuser close to babies or young children, as it’s hard to know the amount they’re inhaling.

Topical Use

Rosemary and other essential oils are readily absorbed into your bloodstream when you apply them to your skin.

It’s generally advised to dilute essential oils with a neutral carrier oil, such as jojoba oil. This helps prevent potential irritation of your skin and premature evaporation of the oil.

Here are some general guidelines for diluting oils for topical use:

Dilution How to prepare it:

Babies   0.3%      Use 1 drop essential oil per 1 tablespoon carrier oil

Children              1.0%      Use 1 drop essential oil per 1 teaspoon carrier oil

Adults   2.0–4.0%             Use 3–6 drops essential oil per 1 teaspoon carrier oil

Once diluted, apply the oil to the bottom of your feet or the body part you’re targeting, such as a sore muscle. Next, rub the oil into your skin. This improves blood flood and absorption of the oil.

Avoid applying rosemary and other essential oils to damaged skin or near sensitive areas, such as your eyes.

It’s generally advised to avoid rosemary oil if you’re pregnant or have epilepsy or high blood pressure. Rosemary oil may worsen the latter two conditions.

You can inhale rosemary oil or apply it to your skin. A diffuser can help distribute the essential oil in a room. If using rosemary oil topically, dilute it with a carrier oil, such as jojoba oil, to avoid skin irritation.