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Health Benefits of Basil Oil + Side Effects, Uses, Dosage

Written by Carlos Tello, PhD (Molecular Biology) | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Carlos Tello, PhD (Molecular Biology) | Last updated:

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Basil Oil

Basil is used in cooking on a regular basis, but what many people do not know is that the oil extracted from basil has many potential health benefits. Basil oil has been used for centuries as a natural remedy for illness and disease. While never becoming a major healing herb in North America, basil oil is still used all over the world as a supplement. Read on to find out more about the health benefits of basil oil.

What Is Basil Oil?

Basil oil is an extract obtained from the leaves of the sweet basil (Ocimum basilicum) plant [1, 2].

Cooking, teas, aromatherapy, and topical applications are common uses for basil oil. It is a natural supplement with many claimed health benefits. Basil oil has been used to treat diseases since ancient times [1].

Components and Mechanisms

The major components of basil oil can vary depending on genetic factors, geographic origin, the plant parts used (stem, leaf, and flower), and the method of extraction. Generally, the main components of basil oil are linalool, estragole, and geraniol [1, 3].

At all doses, these components have the potential to suppress the central nervous system. They may decrease spontaneous activity and cause drooping of the eyelid, decreased muscle control, and sedation [1, 3].

Basil oil interacts with GABA, a neurotransmitter in the brain that is thought to be responsible for stress, anxiety, pain, and epilepsy. However, more research is required to determine exactly how they interact [1, 3].

Snapshot

Proponents

  • May improve teeth health
  • May improve acne
  • May help with headaches
  • May reduce anxiety

Skeptics

  • Insufficient evidence for all benefits
  • Most trials tested it in combination with other herbs or used related basil species
  • Relatively unknown safety profile
  • May irritate the skin
  • Caused liver cancer, reduced platelet count, and menstrual disorders in animal studies

Health Benefits

Insufficient Evidence

1) Teeth Health

In a 21-day clinical trial on 40 people, herbal mouth rinse with basil, tea tree oil, and clove was as effective as a commercial mouth rinse at reducing plaque buildup and improving gum disease. Additionally, the herbal mouth rinse was more effective at reducing salivary bacterial count [4].

A mouth rinse containing the extract of a close relative of basil (Ocimum sanctum, or ‘holy basil’) also reduced the cavities-causing bacteria (Streptococcus mutans) in the saliva in a clinical trial on 60 children. The essential oil of this plant also had antibiotic activity when directly applied into the tooth root canals in another trial on 40 children [5, 6].

Another basil species (Ocimum gratissimum, or ‘clove basil’) reduced plaque and gum disease as effectively as chlorhexidine in a clinical trial on 20 people. However, chlorhexidine was more effective at preventing plaque formation in another trial on 15 people [7, 8].

Because the trials were small and either combined basil oil with other extracts or used the extracts of other related species, there is insufficient evidence to establish if it helps with teeth health. More clinical trials using basil oil alone are needed to draw conclusions.

2) Acne

In a clinical trial on 28 people with acne, those treated with antibiotic formulations containing basil oil and orange peel showed improvement with little discomfort or side effects [9].

In another clinical trial, a topical cream with a basil-derived compound (verbascoside) and chemicals that remove skin tissue (keratolytics) improved this condition. However, multi-ingredient oral supplements were more effective [10].

Basil oil, especially its thickened version, killed a bacteria that causes acne (Propionibacterium acne) in test tubes. The effect was probably due to its content in linalool, which can kill this type of bacteria (gram-positive) [11, 12].

Two small trials (neither of which used basil oil alone) and a study in test tubes cannot be considered sufficient evidence to attest to the effectiveness of basil oil in people with acne. Larger, more robust clinical trials are needed to confirm these preliminary findings.

3) Headaches

In a clinical trial on 19 middle-aged women, 5 days of aromatherapy with a blend of basil, lavender, rosemary, and rose oil greatly improved headache symptoms [13].

A single clinical trial using basil oil in an aromatherapy blend is clearly insufficient to support this use. Further clinical research is needed.

4) Anxiety

Basil oil treatment helped decrease memory impairment, brain (hippocampus) damage, and depression caused by chronic unpredictable stress and decreased the levels of the stress hormone corticosterone in a study in mice [14].

In a clinical trial on 35 people with generalized anxiety disorder, holy basil leaf extract reduced stress and depressive mood [15].

Again, a single clinical trial (which used a different basil species) and some animal research are insufficient to back this potential health benefit of basil oil until more research is conducted.

5) Diabetes

Basil oil reduced the activity of two enzymes that raise blood sugar levels (amylase and glucosidase), suggesting it may help with type 2 diabetes [16].

In a clinical trial on diabetics, holy basil leaves reduced blood sugar levels before and after meals [17].

Similar to the previous case, the only clinical trial used a different basil species. More studies using Ocimum basilicum are needed.

6) Insect Repellent

Basil oil acted as a repellent against the mosquitoes that transmit yellow fever (Aedes aegypti), malaria (Anopheles minimus), and several diseases that affect both humans and animals, including Zika (Culex quinquefasciatus) in a trial on a volunteer. This result should be replicated in larger clinical trials.

Animal and Cell Research (Lack of Evidence)

No clinical evidence supports the use of basil oil for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.

Infections

In rats, basil oil treatment caused a 56-81% cure rate of ear infections in those infected with the common flu virus and a 6-75% cure rate in those infected with pneumonia. It was more effective than any of the other essential oils used in the study [18].

In test tubes, basil oil prevented the growth of 61 different E. coli strains (1 standard strain and 60 strains taken from patients with infections of the respiratory tract, stomach, urinary tract, and skin). Its component linalool was the one with the strongest antimicrobial activity [19].

In another study, basil oil killed the following potentially infectious fungi [20, 21]:

  • Aspergillus niger (may cause lung infections)
  • A. fumigatus (may cause infections in people with a weakened immune system)
  • Rhizopus stolonifer (may cause infections in people with a weakened immune system)
  • Cryptococcus (may cause meningitis in people with a weakened immune system)

Note, however, that these are very preliminary results that haven’t been replicated in humans and, in most cases, even in animals. Further research is needed to determine if basil oil has any potential to fight the infections caused by these microorganisms.

Pain

Basil leaves produce essential oils rich in monoterpenes, which may help manage pain.

In a study in mice, both basil oil and linalool reduced pain perception in a region abundant in pain receptors (upper lip) [22].

In mice with fibromyalgia, oral basil oil supplements decreased pain [23].

Blood Pressure

Basil oil reduces the activity of two enzymes proven to play a role in high blood pressure (amylase and glucosidase) [16].

In rats applied with medication for blood pressure on the skin (labetalol hydrochloride), basil oil enhanced its absorption [24].

Asthma

In a study in guinea pigs, basil acted in a similar way to inhalers (by relaxing the airways) [25].

Stroke

In mice, pretreatment with basil oil before inducing a stroke reduced brain damage and cognitive impairment [26].

Side Effects

Keep in mind that the safety profile of basil oil is relatively unknown, given the lack of well-designed clinical studies. The list of side effects below is not a definite one and you should consult your doctor about other potential side effects based on your health condition and possible drug or supplement interactions.

Basil oil contains both pro- and anticancer substances. The antioxidant properties help prevent cell damage that is believed to contribute to cancer. However, basil oil also contains estragole. In one study in rats, this chemical produced liver tumors. Nevertheless, the FDA classifies basil oil as generally recognized as safe [27, 28, 29].

In one study, rats had reduced platelet count after basil oil treatment. This suggests people with bleeding disorders or on blood thinners should be cautious when taking basil oil supplements [30].

Basil oil is very concentrated, which means it may cause irritation if applied to the skin [9].

In a study in female rats, basil oil disrupted the menstrual cycle. Basil oil also decreased the weight of the ovaries and increased cholesterol levels of the uterus [30].

The monoterpenes and essential oils in basil oil cause poor chemical stability, poor water solubility, and a very quick decomposition rate. This limits the pharmaceutical applications of basil oil [28, 31].

Limitations and Caveats

There are very few clinical trials (many of which used basil oil in combination with other extracts or obtained it from other species than Ocimum basilicum) and most of the research has been carried out in animals. More clinical research using basil oil alone is needed to confirm these preliminary results.

Natural Sources and Forms of Supplementation

Basil oil is extracted from the leaf, stem, or flower. Extraction occurs through distillation, fermentation, crushing, hydrolysis, airing, and especially steam-distillation [1].

Basil oil is most commonly taken in the form of a tea or used in aromatherapy [32, 28, 33].

Dosage

Because basil oil is not approved by the FDA for any condition, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if basil oil may be useful as a complementary approach in your case and which dose you should take.

For tea, the studies used 2-3 teaspoons per 1 cup of boiling water [32, 34].

Basil oil can also be applied topically with a cotton ball after washing the face. Because it can be irritating to the skin in large amounts, it is important to follow the application instructions [32, 34].

User Experiences

The opinions expressed in this section are solely those of basil oil users, who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.

Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.

Some users reported feeling invigorated immediately after consuming basil oil. They praised the oil for being refreshing and helping decrease their stress.

However, a user complained that undiluted essential oils used during massage therapy on her back caused a rash and headache.

About the Author

Carlos Tello

Carlos Tello

PhD (Molecular Biology)
Carlos received his PhD and MS from the Universidad de Sevilla.
Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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