14 Oil of Oregano Benefits & Uses Scientifically Scrutinized
[toc]Sure, it makes spaghetti and pizza sauce taste great, but this herb may be useful for a lot more.
What is oregano oil? It’s an essential oil that’s made by steam distilling the leaves and stems of the Origanum vulgare plant. What remains are the volatile organic compounds. Since those only represent 1.7% to 2% of the plant, it means at least 50 lbs. of the fresh herb is needed to make just 1 lb. of this oil. (1)
There is no difference between oregano oil vs. oil of oregano. They’re just two different names for the same thing.
Differences between species
You will see brands market it with descriptors like wild, Greek, Mediterranean, Mexican or even a combination of these terms (i.e. wild Mediterranean oregano oil). Not all of these are considered authentic, as they are different plants:
Both of these geographic names reference the same thing; Origanum vulgare. This species is known as being the true version.
A hybrid cross of the Mediterranean with sweet marjoram; Origanum majorana.
Despite its common name, the Lippia graveolens plant is from a totally different family.
This term is half-marketing, half-truth. It’s of the same species as Mediterranean or Greek, but it’s a subspecies of it that’s native to the mountainous regions of Turkey and Greece. At only 6-8″ in height, the Origanum Vulgare hirtum subspecies is denser than the sprawling Origanum vulgare. Small stature, but a bigger taste.
What is the best oregano oil?
Some sources claim that wild harvested is the only quality form for purported medicinal uses and research, but that’s not entirely accurate.
For starters, when you analyze the Greek spice and the “wild” subspecies (Origanum vulgare vs. Origanum vulgaris hirtum), you will often find that BOTH are the same thing. That’s because almost all dried spice today that’s labeled as Greek oregano is actually using the hirtum subspecies. It packs more flavor, which is why the spice manufacturers use it.
When buying the fresh herbs, it’s less predictable as to which one you are getting.
Even if an essential oil is made using plain Origanum vulgare, the active ingredients of carvacrol and thymol are the same as hirtum, though admittedly, they may be inferior in concentration.
The most legitimate reason why people can claim “wild” is different is because it’s only used to describe the hirtum subspecies, while the word “oregano” may or may not be describing it.
Both are quite different than Mexican oregano (Lippia graveolens), Spanish oregano (Thymus Capitus), and sweet marjoram (Origanum majorana).
Don’t be fooled by marketing that says the oil needs to be wild or mountain harvested. Sure, that at least assures you it’s the hirtum subspecies, but the hirtum can also be conventionally and organically farmed.
Given that 98% of the plant is discarded during the oil production process, they need a lot. Do you really think guys are running around mountains to pick these wild leaves here and there?
If not a formal farm, harvesting it from a similar designated growing area seems probable.
The use of the word “wild” is not regulated in the United States. Just because your mind may conjure up images of people foraging the forests for the plant, don’t assume that’s what “wild” means.
As long as it’s made using the hirtum subspecies, it’s the best choice for oil. That’s regardless of whether or not it’s called wild.
The uses center around it two main constituents; thymol and carvacrol. Potential advantages for human health remain unproven, but in lab research the oil has demonstrated benefits of being antibacterial, antifungal, and antiviral. For that reason, many believe the oil or derivatives from it might be good for developing new treatments for antibiotic resistance infections. Its antioxidant and anti-inflammatory effects may also offer additional health advantages.
Though to reiterate, these are only theoretical. The research and limited clinical data differs dramatically from what some bloggers are inferring as fact.
Here’s a review of where the science currently stands…
14 oregano oil benefits
1. Broad antibacterial activity
Perhaps the most promising potential for this plant is its antimicrobial activity. This is largely due to the carvacrol.
Is oregano oil an antibiotic? No, an antibiotic is a treatment which is proven effective (a medication). Even though this oil has demonstrated antimicrobial effects against dozens of pathogens, all of it has taken place in laboratory settings. Humans have never been tested. What works in the lab or rodents doesn’t always translate to human health, so for now this benefit is only a potential for research.
To give you a sampling of what scientists have observed…
Three different multidrug-resistant cystic fibrosis pathogens were tested; methicillin-resistant Staphylococcus aureus (MRSA), Stenotrophomonas maltophilia and Achromobacter xylosoxidans. A total of 59 strains of these were tested with oregano essential oil and it was said to be “effective against all tested strains, although to a different extent.” (2)
A synergistic effect was observed when oregano oil andcolloidal silver (biologically synthesized) were used together on gram-positive and gram-negative bacteria, including resistant strains such as MRSA and carbapenemase-producing Escherichia coli. The latter is a common culprit in kidney infections and food poisoning. (3)
With Staphylococcus aureus, which causes staph infections, a synergistic effect was observed with oregano and rosemary essential oils together. (4)
It “yielded highly significant or moderate activity” against Streptococcus mutans, which can cause gum infections and tooth decay. (5)
Klebsiella infections are on the rise. It’s a natural part of the human gut flora and can also be found in our mouth and skin, but when it gets in the lungs, it can cause pneumonia. Small intestinal bacterial overgrowth (SIBO) can be caused by too much Klebsiella growth, among other species. This results in fermented activity taking place too high up in the digestive tract, causing unintended weight loss, diarrhea, gas and bloating. (6)
In the lab, Klebsiella and oregano oil have been tested in combination with the antibiotic doxycycline, without an adverse drug interaction seen. Rather the oil seemed to boost the effectiveness of the doxycycline, by altering the bacterial membranes, so they were more susceptible to the antibiotic working. (7)
When just the oil alone was tested against Klebsiella, it too showed high antibacterial activity. (8) (9) (10)
Oregano oil kills good bacteria, too. Or at least the preliminary evidence of how it works – by affecting the bacterial membrane – would mean both bad and good types could potentially be affected. For a disease like SIBO where there is an overgrowth of otherwise good bacteria, that might be beneficial. Other natural antibiotics demonstrate a similar activity, so this is not unusual.
In the 90’s there was a paper published about testing this essential oil on two probiotics; Lactobacillus plantarum and Lactobacillus plantarum. It was found to inhibit their growth. (11)
So if you’re taking oregano oil capsules or the food grade liquid drops, it would probably be a good idea to also supplement with a good probiotic likethese PRO-15 time released pearls.
Destroying both good and bad bacteria is what antibiotics do and it’s usually worth it, because the bad pathogens being killed off are far worse than a temporary reduction of probiotics in the gut.
In the past it was part of traditional medicine in Europe. Originally sourced from the Greek island of Crete, the use of leaves or oregano oil for cough and sore throats was historically recorded, but not scientifically vetted in modern times. Aside from bacterial infections, other things can cause coughing like the common cold, influenza, asthma, COPD, and more, so it’s unclear what causes it was being used for in the past. (12)
Remember, none of these applications have been tested in humans. It should NOT be used to treat or prevent an infection.
That may sound high when you consider it’s over 3x that of blueberries, but ORAC uses the same weight for each test; 100 grams worth.
100 grams could easily be a typical serving size for blueberries, but for the oil, you would only be using a drop or two if it’s food grade (others are not safe for internal use). That means the ORAC value realized per serving would be less than 1% of 15,300.
3. Kills parasites
Several studies revolving around the poultry industry suggest that killing parasites with oregano oil might be a good alternative to chemical treatments.
The red mite, Dermanyssus gallinae, is a major problem for chicken producers. It was found to have lasting effects against these mites even after 15 and 30 days. (13)
The tick, Rhipicephalus turanicus, affects the cattle industry. In the lab, pure carvacrol was found to kill all of them after 6 hours exposure. Even lower concentrations of 6.25% and 12.5% accomplished the same by day two. (14)
In a study using 250 broiler chickens, some were fed a daily oregano oil dosage equal to 500 parts per million. It appeared to have a beneficial effect on the prevention of the Coccidia parasite. (15)
Another parasite that affects broilers, Eimeria tenella, was also found to be thwarted when this essential oil was part of their diet. Though it did not work as well as the common veterinarian medication, lasalocid (Bovatec). (16)
Lyme disease is a tick-borne illness. Even though some types of ticks have been studied, there’s nothing about oregano oil and Lyme disease that’s been published. Nor is their evidence of it working for the black legged or deer tick which spreads that disease.
4. Repels mosquitoes
DEET is very effective at reducing rates of malaria, the Zika virus, and other infections carried by mosquitoes. Though given the health risks of this chemical, research is continuously searching for safer alternatives.
One promising candidate is using oregano oil on skin. It burns, so it can’t be used without dilution.
The Origanum scabrum plant species (related to the Origanum vulgare) was said to offer 100% protection from mosquito bites for up to 210 minutes when adequate concentrations were used. (17)
It appears to be the carvacrol and terpinen-4-ol compounds which these insects hate. (18)
Even though carvacrol is among “the most toxic” for the mosquito, there is a great deal more research on 1,8-cineole from eucalyptus, which has been proven to be an effective natural mosquito repellent that rivals DEET in many ways. (19)
5. Fights fungal infections on dogs
Is oregano oil safe for dogs?
Using it for repelling fleas (Siphonaptera) on canines and cats is something you may come across on a home remedy blog, but its safety and effectiveness for fleas has never been studied.
What has been studied is using it for fungal skin infections. The treatment consisted of a blend, which meant that Origanum vulgare was only one of several essential oils. So whether it works by itself is unknown.
That said, the blend did achieve “a good clinical outcome” for Malassezia pachydermatis, which is a common fungal infection in dogs. There was no reoccurrence, even 180 days later.
What this study does tell us about oil of oregano for dogs is that if diluted properly, it appears safe. The concentration they used in the formula was 0.5%, with a topical application given twice daily for one month. (20)
6. Combats cat haircoat fungus
It’s not just dogs who might benefit. Two studies have tested oregano essential oil on cats, for the haircoat infection of Microsporum canis.
This is a type of fungus that frequently infects the top layers of dead skin cells in pet cats.
Both studies used a natural shampoo with 5% oregano, 5% rosemary, and 2% thyme oils. Sweet almond was used as the carrier oil for dilution.
In the 2012 study, 4 out of 7 cats were cured of the infection. In the 2017 study, all were negative by week 11. (21) (22)
Microsporum canis can infect dogs and humans too, but it’s rare. However other species of the Microsporum genus can cause athlete’s foot and jocks itch.
7. Promotes intestinal barrier integrity
It’s unknown if this benefit exists with in humans, but Chinese scientists claim to have observed this in pigs.
In the study, pigs were fed either a control diet or one that was augmented with 25 mg of oregano essential oil per kilogram of body weight. The latter were said to have:
Decreased endotoxin levels, which are toxins associated with the outer membranes of certain bacteria.
Increased villus height, which are tiny finger-like projections that coat the inner lining of the small intestine.
In the jejunum (the 2nd part of the small intestine) an increased expression of the tight junction protein ZO-1.
Less E. coli in both the small intestine and colon.
Less inflammation due to altered expression of signaling pathways.
In plain English, all of these were good changes, which suggested a healthier intestinal wall. They said these benefits were “probably through modulating intestinal bacteria and immune status in pigs.” (23)
For the pigs getting the oil, you can see how their villus (finger-like projections) are taller and appear healthier.
By citing this study, some people allege oregano oil cures IBS and other digestive health issues, but neither human nor lab research has been done to evaluate such claims.
8. Reduces colitis symptoms
Again, this is specific to animal research only. In this case, it was mice that were studied.
Colitis was induced on them using a known chemical trigger. After that, they were split into 5 different groups.
The first was a control group that wasn’t given colitis.
The second was given colitis, but no essential oils.
Groups 3, 4, and 5 were fed oregano and thyme oil in varying concentrations, all of which were 0.5% or below.
Those getting the essential oils with their food appeared to maintain their body weight better in spite of the colitis. (24)
The top line is the control group. As expected, their body weight remained more or less the same.
Underneath are 3 lines representing different concentrations of oil treatment. Those on the high dosage seemed to maintain body weight better than the non-treated colitis mice, which are represented by the (▪) line.
Now that was using a combination of oils, but a similar study involving rats using only oregano concluded that it had “a significant protective effect on the colonic injury.” (25)
An animal model of Crohn’s disease has not yet taken place, but it would be interesting to see one given this pseudo ulcerative colitis model.
9. Inhibits bacteria that causes UTIs
It has been reported that anywhere from 70 to 95% of upper and lower urinary traction infections are caused by Escherichia coli. This includes kidney infections, which are a specific type of UTI. (31)
Home remedy websites talk of using an oregano oil dosage highly diluted in water for the prevention or treatment of UTI. Trying to get rid of the infection without going to the doctor may sound appealing, but that advice has never been scientifically studied. It could be risky to self-treat because even a relatively mild UTI can turn into something much worse.
That being said, perhaps someday a treatment will be developed. Over a hundred papers have been published on the two active ingredients in oregano, carvacrol and thymol, and how they demonstrate antibacterial activity against E. coli.
Rather than as a medicine, what appears more likely to happen is developing it for use as a preventive measure on organic foods:
“Scanning Electron Microscopy (SEM) demonstrated disrupted bacterial membranes due to the oregano oil treatment. The data suggest that applying oregano oil nanoemulsions to fresh produce may be an effective antimicrobial control strategy.”
That was a quote from a study where fresh lettuce was treated with it. By just dipping the heads for one minute in a 0.05% or 0.1% solution, it was found to be effective against E. coli and two other common foodborne bacteria; L. monocytogenes and S. typhimurium. (32)
10. Destroys Candida yeast
Candida albicans is perhaps the most problematic fungal infection in humans. It causes vaginal yeast infections, oral thrush, and can be chronic infection of the digestive tract.
The use of oregano leaf oil for Candida in humans has not been studied and therefore, it should not be used a treatment for such. It’s unknown if it destroys the fungus when inside of humans.
There is promising research though that suggests someday it might be a benefit, because it has been found to be quite toxic to the Candida in laboratory settings. Over two dozen papers on the topic can be found in the National Institutes of Health’s PubMed database.
It was found to have “highly effective anticandidal activity” on strains isolated from mastitis infections in cows. (26)
How it works appears to be by compromising the cell walls and membranes of the yeast. That’s according to a study where 30 strains of Candida were gathered using swab samples from vaginal yeast infections. They were then observed under microscopes as they were treated with different essential oils. (27)
Using a homemade oregano oil douche or enema is something you may read about online, but that’s never been tested, nor has its safety.
When used as part of plastic packaging material, it was found to offer “complete inhibition” of not only Candida, but also the gram-positive bacteria Listeria monocytogenes and the gram-negative bacteria Salmonella choleraesuis. Scientists hope that by incorporating someday into films used for food packaging, it may help protect against food poisoning. (28) (29) (30)
11. Broad antifungal activity
It’s not just Candida yeast and those specific to cats and dogs which have been studied. There are over a hundred scientific papers relating to its antifungal activity.
Sporotrichosis, known as “rose gardener’s disease” often infects the skin, but it can get to other parts of the body including the joints, bones, lungs, and elsewhere. It has demonstrated antifungal potential against Sporothrix brasiliensis in the lab. (33)
The genus Aspergillus consists of approximately 180 species. They can cause fungal pneumonia and a side effect which often accompanies it, tree-in-bud sign of the lung. Out of 15 essential oils tested in the lab against three strains of Aspergillus infections, oil of oregano offered the 3rd best antifungal activity for it (thyme and clove oil were best). (34)
One reason an Aspergillus infection is so awful is because this fungi produces a carcinogen; aflatoxin B1 (AFB1). When grains such as corn and soybeans were treated with Origanum vulgare oil, it almost completely inhibited their growth and production of alfatoxins. (35):
It also works well against Penicillium in food, coming out as the number one out of eight essential oils tested. (36)
Jock itch, ring worm, and athlete’s foot can be caused by a number of fungi, but the three most common causes are Trichophyton, Epidermophyton, and Microsporum.
Out of 11 different essential oils tested against Trichophyton mentagrophytes in a foot bath, it was said that oregano demonstrated the highest fungicidal activity. Using a water temperature of 108° F for 20 minutes, it was said to have a kill rate of 99.99%. To be clear this was using infected blocks that sat in the foot bath. Actual infected human feet were not used in this test. (37)
Epidermophyton hasn’t yet been tested, but the close cousin marjoram inhibits its growth. (38)
The types of Microsporum that commonly causes athlete’s foot and similar fungal infections in humans haven’t been tested, but as you will recall from above, the oil was said to work for the related Microsporum canis in cats.
Fusarium Keratitis is a fungal infection of the eye’s cornea, often associated with the wearing contact lenses. It has demonstrated inhibitory effects against cultured fungal keratitis, but cinnamon oil did better. Using oregano oil in the eye would be an unlikely candidate for drug development anyway, given its side effect of intense burning. (39)
The plant fungus Botrytis cinerea, which often infects wine grapes and other fruits, has been found to be inhibited by thymol and carvacrol. (40)
Scientists believe that carvacrol and similar monoterpenes might be candidates for developing future therapeutic treatments.
A cancer model used tumors on the paws of mice. When treated with pure carvacrol, pain sensitivity was reduced significantly for up to 9 hours and even longer with the encapsulated form. (44)
That was pain from cancer on the limbs, not specific to joint pain caused by inflammation or arthritis.
When it comes to studying oregano oil for rheumatoid arthritis, the closest thing is a study which concluded that carvacrol seems to boost T cell responses to stress proteins. In turn, that is believed to reduce inflammation. (45)
If this T cell theory is true, it may be of use to multiple types of inflammatory conditions including joint and back pain, tendonitis, and possibly even inflammation related to some allergies and types of cough.
Rubbing the oil on the spine or point of pain is a claimed remedy, albeit unproven. There is only one randomized, double-blind human clinical trial involving topical skin application, but it was on the lower abdomen for menstrual cramps.
A blend of oils was rubbed on the women’s skin during their menstrual cycle; oregano, clary sage, marjoram, and lavender. It was said that pain ratings “significantly decreased” in the treated group, but it was aromatherapy and not just the analgesic qualities which were cited as reasons. Since multiple oils were used, this study isn’t very relevant. (46)
Anti-inflammatory effects were also observed on gastric lesions, paw edema, and ear edema in mice. Those were inflicted injuries. Using oregano oil for ear infections was not part of it. Some natural remedy sites talk of doing that, but it could be quite dangerous given that oil on the skin burns badly. That could cause permanent hearing damage when inside the ear. When it comes to tackling sinus congestion from colds and allergies, similar hazards may exist when using oregano oil in the nose with a Neti Pot. (47)
13. Some antiviral activity
Compared to the 100+ papers on its antifungal properties, less than 10 can be found in the PubMed database about antiviral effects.
The mouse norovirus – which is similar to the human norovirus – was inactivated within one hour of being exposed to carvacrol. (41)
Can oregano oil cure herpes or cold sores caused by that virus? It hasn’t been tested with wild oregano, but it has in the lab with the Mexican variety (Lippia graveolens). Although different species, both have a high percentage of carvacrol.
The Mexican oregano – as well as the isolated carvacrol tested separately – showed noteworthy amounts of activity against two different types of the herpes simplex virus; the type that can be treated with acyclovir (Valtrex) and the type which is resistant to it (HHV-1 and ACVR-HHV-1, respectively). But this was only lab research, so it’s unknown if the same happens with actual cold sores. (42)
The human papillomavirus (HPV) infection which can cause genital warts has not been tested using the wild, Greek, Mexican, or any other variety.
There is also zero research on HIV. Any claims being made about oil of oregano and HIV or AIDs are completely bogus.
Is oregano oil good for a cold? Taking it when sick is one of the uses you will hear about most, but this benefit is not backed by science. The rhinovirus is believed to be responsible for over 50% of common cold infections. It has never been tested, not even in the lab. Likewise for any form of the influenza virus.
With no evidence to support them, many of the wild oregano oil uses for viral infections fall under the myth or scam category. In fact, the Oreganol P73 brand had to pay the FTC a whopping $2.5 million settlement for allegedly making false claims that oil of oregano was scientifically proven to treat colds and the flu. It’s not! (43)
In short, all of the antiviral research is very preliminary.
14. Potential for skin care
In traditional Turkish medicine it has been used for treating inflammatory disorders of the skin like eczema and wound healing. Testing it though has only taken place in rats and it was using a blend that included sage and St. John’s-wort. (48)
Some people talk of removing skin tags with oregano oil. Using it for that or mole removal can cause severe skin burns and its effectiveness has never even been studied.
The best supporting evidence of it possibly benefiting skin care is due to the antibacterial, antifungal, and anti-inflammatory properties. Although unproven, in theory the carvacrol may help with inflammation from acne, rosacea, and eczema. Although it is not the root cause of pimples, the Propionibacterium acnes bacteria often makes them worse, which is why antibiotics are often prescribed by dermatologists.
Aside from the unknown of whether or not using oil on skin can help, the other thing to consider is the potential for burns and resulting scars. That’s why body washes, soaps, and other topical products made with it are highly diluted.
Oregano oil side effects
Burning of skin when topical
Burning of gums and throat when oral
Upset stomach when taken orally
Increased risk of bleeding
Liver damage in high oral dosages
Drug interaction with lithium
Possibly unsafe during pregnancy
Since there’s limited human clinical data, most of the adverse reactions are based off the aforementioned animal studies, as well as product reviews of what people report. The long term use of oregano oil is not recommended, as most dietary supplements list a time period of up to several weeks. It’s not safe for babies, toddlers, or children.
An allergic reaction to oregano oil is more likely if you already experience such with plants in the Lamiaceae family, like basil, rosemary, marjoram, sage, lavender, and mint.
Is the oil safe during pregnancy and breastfeeding? Possibly not, given its analgesic effects and the fact that in research, carvacrol has been found to change dilation in the arteries of both pregnant and non-pregnant rats. (49)
Why does oregano oil burn? This side effect is because of the high amounts of carvacrol, thymol, and other terpenes. So yes, concentrated strengths might work for mole and skin tag removal, but it could be destroying the surrounding healthy skin in the process. That is not a safe or predictable remedy.
The oil’s composition includes the following compounds and percentages, which can all be very irritating and cause burning when they’re not diluted:
8% ß-fenchyl alcohol
Those are the chemicals in high concentration, but the rest of them are also potential irritants. This is not unusual though, because the same holds true with almost all essential oils. (50)
They’re not like culinary oils such as olive and coconut oil. Essentials are made out of the volatile organic compounds, which is why manufacturer instructions only list one or two drops when used internally or pills/capsules filled with a tiny amount. Too much oregano oil can be dangerous for everyone.
For example, Doterra says how to use it in food is to add just one drop, for things such as spaghetti sauce. When not eating it and using it as a supplement, the dosage they claim to “maintain healthy immune function” is still one drop daily. If undiluted, wild oregano oil under the tongue can burn, so even that single drop should be mixed with an edible carrier oil like coconut, or diluted in 4 ounces of water for drinking. Uses in mouthwash for bad breath is another idea for dilution.
Where to buy?
Many pure oils are labeled for aromatherapy (therapeutic grade) and cannot be taken internally. The food grade oregano essential is typically sold in capsules or a small bottle. Since internal use is typically a dietary supplement, you won’t find it for sale at places like Walmart and Target or traditional grocers like Kroger. Whole Foods and Sprouts each carry a few brands.
Reviews of brands
If you want to make sure you are buying wild oregano (Origanum Vulgare hirtum), then you should stick with the following:
Joy of the Mountains
Lifetime oregano oil and olive leaf
Quantum Nutrition Labs
Please note that not all varieties from a given brand are of the Origanum Vulgare hirtum, so make sure you check the label.
North American Herb & Spice with their “super” or extra strength oregano oil P73 is probably the most recognized brand, but remember that FTC settlement they had to pay. Given the alleged exaggerations of health benefits the company used in marketing, it makes us a bit hesitant to buy their products.
Should you use oregano oil vs. pills? The advantage of the latter is that the amount per serving is controlled. With the liquid oil, you have to be more careful so you don’t take too much. Regardless of the form you choose, follow the product instructions carefully.
On Amazon, here are the products we like the best…
For pure liquid: Zane Hellas uses a different subspecies of wild Greek (Origanum vulgare heracleoticum) which has a staggering 86% concentration of carvacrol. You can buy it as a 1 oz. dropper.
Remember these products are for use as dietary supplements only. They are not something which should be used for any disease treatment. As with all supplements, consulting your doctor prior to use is recommended.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
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