Oregano oil: Benefits, side-effects, uses and dosage

Oregano is a commonly used herb in Italian cooking. A concentrated herbal supplement, often called oregano oil, can also be made from it. 

Even though oregano is a well-known herb and a staple in many kitchens, essential oils derived from oregano leaves contain a much higher concentration of oregano than herbal supplements. Instead, the essential oil is used topically and through inhalation to treat specific health conditions. The herbal oil can be taken as a herbal supplement.

Phenolic glycosides (phenols) are present in oregano oil. These compounds have antioxidant and antimicrobial properties. 

Phenols, such as carvacrol, cymene, terpinene and thymol, are responsible for much of the composition of oregano oil. Phenols are said to be responsible for the health benefits of the oil.

How is oregano oil made?

The herb oregano (Origanum vulgare) belongs to the mint family (Labiatae). Folk medicines around the world have used it for over 2,500 years as a valuable plant commodity and has a very long use in conventional medicine for treating upset stomachs, indigestion and colds. 

Medicinal-grade oregano is found in the Mediterranean, throughout Europe and South and Central Asia, where it is distilled to extract the essential oil, which contains a high concentration of active constituents. Almost 1,000 pounds of wild oregano are needed to make a pound of oregano essential oil.

How is oregano oil made?

Both topically and internally, essential oils are used to preserve the oil’s active ingredients. As a natural alternative to prescription antibiotics, oregano oil is often known as “oil of oregano.”

In studies, Carvacrol and thymol, found in oregano oil, have been shown to possess potent antibacterial and antifungal properties. A major component of oregano oil is carvacrol. At the same time, studies show that the plant’s leaves contain various antioxidant compounds, like phenols, triterpenes, rosmarinic acid, oleanolic acid and ursolic acid [1].

Carvacrol has demonstrated a wide spectrum of activity against food spoilage fungi, yeast, bacteria, and human, animal and plant pathogens, including drug-resistant and biofilm-forming microorganisms.

It has been shown that carcavol in oregano essential oil can reverse or reduce some of these common health problems [2] :

  • Bacterial infections
  • Fungal infections
  • Parasites
  • Viruses
  • Inflammation
  • Allergies
  • Tumors
  • Indigestion
  • Candida

Several studies have shown that oregano oil is a highly effective, plant-derived essential oil that may rival antibiotics in treating and preventing infection [3]. As well as being antibacterial, it is also antiviral and antifungal.

It is also unlikely that oregano essential oil will cause many of the side effects commonly associated with high antibiotic usage, such as antibiotic resistance, poor gut health due to the destruction of probiotic bacteria, reduced vitamin absorption,and leaky gut syndrome due to damage to the gastrointestinal tract’s lining [4].

Uses of oregano oil

The oil may be available in supplement form, as a pill and as a soft gel capsule. Since oregano oil is so potent, these usually contain other ingredients to dilute it. When the capsules are not full strength, they can be taken orally or applied topically.

If it’s not premixed, you will need to dilute it yourself by mixing it with carrier oils like coconut or olive oil. The usual proportion is 5 to 6 drops for every ounce of carrier oil.

After diluting the essential oil, it can be applied topically. Consult a certified aromatherapist before taking any essential oil orally. It is important to note that some essential oils are toxic and their qualities can differ.

Steam can also be used to inhale oregano essential oil. One or two drops of oil should be placed in a steaming water bowl or vaporiser.

Oregano has primarily been studied in vitro, in animals and in small human trials. Despite the promising results of this research, more definitive proof of oregano oil’s effectiveness is needed. Even so, this product is marketed for a variety of purposes.

Cook with the herb or take it as an herbal supplement to:

  • Bacterial infections (E. coli)
  • Viruses, like the norovirus (stomach virus) or upper respiratory infections
  • Small intestinal bacterial overgrowth (SIBO)
  • Parasitic conditions
  • Urinary tract infections (UTIs)
  • Yeast infections (Candida)

The essential oil can be used as a vapour for the following:

  • A cough
  • Asthma
  • Bronchitis
  • Respiratory infections

Apply the diluted essential oil topically to:

  • Acne
  • Bug bites
  • Dandruff
  • Poison ivy
  • Topical infections

In further detail, let’s explore some of the oil’s most common uses:

Oregano oil as a natural alternative to antibiotics

When antibiotics are used frequently, what are the risks? Antibiotics with a broad spectrum of activity can be dangerous because they kill not only bacteria responsible for infections, but also good bacteria we need to stay healthy.

The Wall Street Journal published an excellent article in 2013 outlining the dangers associated with repeated use of antibiotics [5]. According to the author, “Recent studies show that doctors are overprescribing broad-spectrum antibiotics that kill both good and bad bacteria in the body.”

When antibiotics are overused, or when broad-spectrum drugs are prescribed when they are not needed, a range of problems can occur. By fostering the growth of antibiotic-resistant infections, it can reduce the effectiveness of the drugs against the bacteria they are meant to treat. It can also wipe out the body’s good bacteria (probiotics), which aid digestion, vitamin production, and immunity to infections.

Infections caused by viruses are typically treated with broad-spectrum antibiotics, even though they are useless for such conditions. Researchers from the University of Utah and the Center for Disease Control and Prevention found that 60 per cent of the time, physicians prescribe broad-spectrum antibiotics [6].

Pediatrics published a similar study of children that found 50 per cent of antibiotics prescribed to children were broad-spectrum, often for respiratory conditions [7]. In comparison, what does oil of oregano do for you that makes it so helpful? To protect your health, oregano oil is a “broad-spectrum approach.”

Multiple types of pathogens, such as bacteria, yeast and fungi, are fought by its active ingredients. The Journal of Medicinal Food said in 2013 that oregano oils could be used to treat pathogenic systems.” [8]

Oregano oil benefits

Defends against infections and bacterial overgrowth

There is evidence that oregano essential oil can help combat some strains of bacteria that cause health problems that are usually treated with antibiotics.

The benefits of oregano oil for these conditions are as follows:

  • The use of oregano oil instead of harmful antibiotics has been verified by dozens of studies.
  • Oregano oil was evaluated for antibacterial activity against five different types of bad bacteria in the Journal of Medicinal Food in 2011. As a result of evaluating oil of oregano’s antibacterial characteristics, it was found to exhibit significant antibacterial properties against all five species. The highest activity was observed against E Coli, which suggests that oregano oil could be routinely used to promote gastrointestinal health and prevent deadly food poisoning.
  • During a 2013 study published in the Journal of Science of Food and Agriculture, researchers concluded that oregano extracts and Portuguese essential oil could be used as a substitute for synthetic chemicals. According to the study, origanum vulgare inhibited the growth of seven bacteria strains that other plant extracts could not after studying its antioxidant and antibacterial properties [9].
  • An animal study published in the Brazilian journal Revista Brasileira de Farmacognosia also found that oregano oil was effective against pathogenic fungi as well as bacteria [10].
  • The active compounds in oregano oil (such as thymol and carvacrol) have been shown to help treat bacterial infection-induced toothaches and earaches. The Journal of Infectious Diseases published a study in 2005 that concluded “Essential oils or their components are effective in treating acute otitis media.” [11]

Oregano oil helps reduce the side effects of drugs and medications

Recent studies have found that oregano oil may help reduce the side effects of medications and drugs as one of its most promising benefits. Despite the horrible suffering associated with drugs and medical interventions (chemotherapy or drugs for arthritis), these studies give hope to those who wish to manage them.

In a study published in the International Journal of Clinical and Experimental Medicine, phenols in oregano oil helped protect mice against methotrexate toxicity [12]. Aside from treating cancer and rheumatoid arthritis, methotrexate (MTX) has some dangerous side effects. 

Scientists believe oil of oregano’s antioxidant and anti-inflammatory properties are responsible for oregano’s ability to fight these factors. MTX’s side effects are more effectively prevented by oregano than by ineffective drugs.

Carvacrol was observed for the first time to decrease the pro-inflammatory response in mice treated with MTX by evaluating various markers in the sciatic nerve. It is likely that there will be more studies testing these results since “groundbreaking” does not even begin to describe the significance of this potential oregano health benefit, since it is a relatively new concept in the scientific world.

Similarly, research conducted in the Netherlands showed that oregano essential oil can also avoid the overgrowth of bacteria and colonisation in the large intestine during oral iron therapy.” [13]

Carvacrol targets gram-negative bacteria’s outer membrane and increases membrane permeability, thereby killing them. Furthermore, carvacrol interferes with certain pathways for bacterial iron handling, which helps lower the side effects of iron therapy.

Aids in the treatment of athlete’s foot

In one study, heat, salt, and essential oils (including oregano) inhibited the growth of mycelia of T rubrum and conidia of T mentagrophytes, commonly responsible for athlete’s foot infections.

It was concluded by the researchers that combining thermotherapy with essential oils and salt would be promising for treating tinea pedis in a foot bath. Among 11 essential oils tested against bacteria that contribute to athlete’s foot, oregano oil was found to be most potent (followed by thyme, cinnamon bark, lemongrass and clove [14].

Provides relief from digestive problems (including SIBO and heartburn)

Several of the active compounds found in Origanum vulgare can help aid digestion by relaxing the muscles of the GI tract and also helping balance the ratio of good-to-bad bacteria in the gut. Thymol, one of oregano’s active compounds, is a similar compound to menthol, which is found in peppermint oil. 

Like menthol, thymol may help relax the soft tissue of the throat and stomach, which can help to decrease GERD, heartburn and discomfort after eating. Because it helps balance bacteria and fights yeast overgrowth, oregano essential oil is also a popular natural treatment for candida and SIBO. 

SIBO is a common digestive problem that causes gas, bloating and intolerances to many carbohydrate-containing foods (especially FODMAPs). Origanum vulgare hinders bacterial replication and can be used similarly to antibiotic medications, such as rifaximin (Xifaxan), for treating infections that affect digestive health and nutrient absorption.

A 2014 study published in Global Advances in Health & Medicine found evidence that use of herbal antimicrobials is just as effective as the antibiotic usually given for the treatment of SIBO. When 104 patients diagnosed with SIBO (via lactulose breath test) were treated either with rifaximin (1,200 milligrams) or herbal antimicrobials over the course of four weeks, the results showed that 46 percent of the patients treated with herbal antimicrobials experienced symptom improvements compared to only 34 percent treated with the antibiotic rifaximin.

Additionally, 14 of the 44 patients who still had SIBO after a course of rifaximin were then treated with herbal antimicrobials. Fifty-seven percent responded positively to the herbal treatment even after failing to feel better from the antibiotics [15].

Helps treat parasites

According to one study, adults whose stools tested positive for enteric parasites (including Blastocystis hominis, which causes digestive distress) supplemented with 600 milligrams of oregano for six weeks reported significant improvements in their gastrointestinal symptoms. Four cases of Entamoeba hartmanni were reported missing, one case of Endolimax nana was reported missing, and eight cases of Blastocystis hominis were reported missing. Symptoms like nausea, gas, bloating, and abdominal pain improved in seven of 11 patients with Blastocystis hominis [16].

Manages inflammatory conditions (such as rheumatism or IBD)

Whether fresh or dried, oregano retains its high antioxidant capacity. A high concentration of antioxidants in oregano essential oil helps reduce oxidative damage and prevents mutagenesis, carcinogenesis and aging due to its free radical-scavenging properties [17].

It is believed that free radicals contribute to chronic conditions such as cancer, cardiovascular disease, neurodegenerative disorders, and drug toxicity. According to one study, combined treatment with thyme and oregano essential oils may help prevent colitis (an inflammatory bowel disease) in mice [18].

Research has also shown that oregano oil can treat respiratory disorders, tumors, and rheumatoid arthritis. A study from the Universidad Nacional de Córdoba in Argentina indicates that essential oil isolated from Origanum vulgare “presents antibacterial, antioxidant and chemopreventive properties and could be play an important role as bioprotector agent.” [19]

It may help lower cholesterol levels

Research published in the Journal of International Medical Research reports that adding oregano oil supplementation can improve cholesterol levels [20]. A low-fat dietary plan and lifestyle advice were given to 48 patients with mild hyperlipidemia. 

In the study group, 32 patients were prescribed 25 ml of oregano distillate each day after meals for three months, while 16 patients were in the control group. The study group showed statistically significant greater increases in high-density lipoprotein (HDL) cholesterol and significantly greater decreases in low density lipoprotein (LDL) cholesterol following a three-month study period.

Preparation of oregano oil for use

The oil of oregano can be applied topically, diffused, or taken internally (only if it’s a therapeutic grade oil). It is ideal to purchase oregano oil that is 100 per cent pure, unfiltered and certified USDA organic. You can also buy oregano oil soft gels or capsules to take internally.

It is always a good idea to mix oregano essential oil with a carrier oil, such as coconut oil or jojoba oil, before using it on your skin. By diluting the oil, you reduce the possibility of irritations and adverse reactions. Topically, mix three drops of oregano oil with your carrier oil and apply to the affected area by rubbing it into the skin.

Here are a few other ways to prepare oregano oil:

As a natural antibiotic: Apply it topically or internally for 10 days at a time, diluted with a carrier oil.

For battling Candida and fungal overgrowth: 

For toenail fungus, you can make a homemade antifungal powder that can be applied to your skin. Add 3 drops of oregano oil to the powder and stir well. Sprinkle the powder on your feet. For internal use, take 2 to 4 drops twice daily for up to 10 days.

In fighting Pneumonia and Bronchitis: For external infections, apply 2 to 3 diluted drops to the affected area. To prevent internal bacterial overgrowth, ingest 2 to 4 drops twice daily for up to 10 days.

Fighting MRSA and Staph Infection: Add 3 drops of oregano oil to a capsule or to the food or beverage of your choice along with a carrier oil. Take it twice daily for up to 10 days.

For Intestinal Worms and Parasites: Take oregano oil internally for up to 10 days.

Helping to remove warts: Dilute it with another oil or mix it with clay.

Cleansing mold From the Home: Add 5 to 7 drops to a homemade cleaning solution along with tea tree oil and lavender.

Oregano essential oil dosage

Oral supplementation of emulsified oregano is usually taken in one or two doses, depending on the condition you’re treating. You can purchase pre-made oregano tea or make your own by steeping 15g of oregano leaves in 250 ml of water for at least five to ten minutes (for a more potent herbal infusion, steep for as long as 24 hours). Ask your doctor if oregano oil can interact with other medications before taking it internally.

Usage and dosage reminders

The dosage of oregano oil for people hasn’t been studied in depth. However, manufacturers recommend doses based on the amount of phenols and thymol in the oil.

It is important not to exceed the recommended dosage or use oregano oil in any form, including on the skin, for several weeks. A little goes a long way when applying oregano essential oil. One to two drops of diluted oil may seem insignificant, but in excess, you may experience adverse reactions.

Side effects and risks

When used as directed, oregano oil should be non-toxic. In too-high doses, it may pose adverse effects, unlike the herb you cook with.

There is a likelihood that this may be due to thymol, one of the phenols in the product. Thymol can cause mild irritation of the skin and internal organs in high doses, resulting in:

  • Central hyperactivity (inappropriate talkativeness)
  • Gastric distress
  • Nausea
  • Vomiting

Oregano oil should not be used on or near broken skin or on or near the eyes because thymol can also be irritating or corrosive. If you are allergic to oregano, or other plants in the Lamiaceae family, such as mint, sage, basil, or lavender do not use oregano oil.

Even people who are not allergic to oregano oil may get a skin rash when using diluted oil topically. If you’re using capsules or essential oil, follow the instructions on the package carefully.

Oregano oil has not been tested for safety in children or pregnant or breastfeeding women. These populations should not use oregano oil. There is some concern that oregano oil may cause miscarriage or contractions in the uterus [21].

When to see your doctor

It is vital not to inhale oregano oil if you are allergic to it. Doing so can cause inflammation of the airways and could quickly become dangerous.

There are a number of symptoms that may warrant a doctor’s visit after prolonged exposure to thymol, including:

  • Diarrhea
  • Difficulty swallowing
  • Excessive salivation
  • Fatigue
  • Headache
  • Muscle pain
  • Vertigo

Although oregano oil is claimed to relieve symptoms and cure medical conditions, there is little evidence to support these claims. Follow dosage instructions carefully and consult your doctor before taking oregano oil in supplement or essential oil form. You should always dilute essential oils because they are much stronger than supplements. Infants, children, and pregnant or nursing women should not use oregano oils [22].

[1] https://pubmed.ncbi.nlm.nih.gov/21772760/
[2] https://pubmed.ncbi.nlm.nih.gov/22044355/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3868303/
[4] https://draxe.com/health/antibiotic-resistance/
[5] https://www.wsj.com/articles/antibiotics-dos-and-donts-1376953921
[6] https://academic.oup.com/jac/article/69/1/234/848592
[7] https://pediatrics.aappublications.org/content/early/2017/03/03/peds.2017-0027
[8] https://bit.ly/3VL9u2b
[9] https://pubmed.ncbi.nlm.nih.gov/23553824/
[10] http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-695X2014000100025
[11] https://pubmed.ncbi.nlm.nih.gov/15871121/
[12] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4658926
[13] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3957860/
[14] https://pubmed.ncbi.nlm.nih.gov/17287720/
[15] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030608/
[16] https://pubmed.ncbi.nlm.nih.gov/10815019/
[17] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4804097/
[18] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233768/
[19] https://pubmed.ncbi.nlm.nih.gov/25266989/
[20] https://pubmed.ncbi.nlm.nih.gov/19094443/
[21] https://www.healthline.com/health/miscarriage
[22] https://www.healthline.com/health/oregano-oil-side-effects#when-to-see-your-doctor

The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.