oregano plant

12 Strongest Natural Antibiotics, Backed By Science

[toc]When you hear antibiotic, the first word that pops in your mind is probably something like amoxicillin, penicillin, or Cipro. Whether it’s a toothache caused by an infection, bronchitis, or open wounds, chances are you will be given this class of medication by your doctor.

While they certainly are NOT a substitute for prescription treatments, it is interesting to see the many foods, herbs, and spices which demonstrate antimicrobial activity in vitro (in laboratory experiments). They are called “natural” but to be clear, these should not be confused with antibiotic medications.

Rather, these are something completely different – organically occurring substances which demonstrate at least some antimicrobial activity in experiments. That’s all. They are NOT an alternative or over the counter replacement for medication.

Use in pets and livestock?

On a number of websites, you will read about people using these so called natural antibiotics for dogs, cats, and even chickens or turkeys which will later become human food (and hence, they don’t want the birds pumped full of prescriptions).

French bulldog sitting in swingOne lady purported DIY homemade antibiotics for cat abscesses, using a mixture of myrrh and goldenseal. She claimed the remedy worked on her kitten, but as a treatment it is totally unproven and may not be safe.

That being said, those particular ingredients have shown potential in the lab (more on those below).

Dogs Naturally Magazine has floated the idea of Manuka honey not just for abscesses, but purportedly as an effective remedy for kennel cough and ringworm. It’s produced in New Zealand and Australia, using the nectar of the Manuka tree.

They claimed it “shines” as a natural antiseptic for dog wounds because of its phytochemicals, which are not found in other types of honey. Furthermore, they said it may possess antifungal and antiviral benefits.

Chickens with a cold or with mites are normally shot up with chemicals, but not everyone is doing that.

The New York Times ran a story a few years back about a poultry farm in Pennsylvania switching to natural antibiotics for their chickens, in the form of oregano oil (1):

“Mr. Sechler [the farm’s owner] swears by the concoction as a way to fight off bacterial diseases that plague meat and poultry producers without resorting to antibiotics.”

For around three years, he has been using feed which has been supplemented with a smidgen of oregano oil and cinnamon.

Mr. Sechler claimed that no antibiotic alternative he had previously used worked as well as oregano oil. He might be onto something because as an animal food additive, it has been evaluated for possible effectiveness against strains of Dalmonella, E. coli, Enterococcus faecalis, and staph infections. (2):

Use in humans?

Using these for a goat or guinea pig may be one thing, but holistic care like this is not something which should be carried out without the approval and guidance of your medical doctor.

There are no medically approved natural antibiotics for humans. Using foods or essential oils for a bacterial infection is not only unproven, but also dangerous. No one even knows how effective or not they would be if used in humans.

bacteria and fungus in petri dishFor example, the use of essential oils for ear infections is commonly touted on naturopathic websites. You hear about rosemary, oregano, and basil oil among others being used.

They claim they’re effective, but they have not been proven – and often times not even studied – for ear aches, wax buildup, or other ear applications.

Something which seems benign – like a tiny infection on the skin of your finger – can spread throughout your body and become a life threatening disease. In the elderly and those with a compromised immune system due to cancer or HIV, the risks which bacteria pose are even greater.

It’s why real healthcare is the treatment you need to seek, regardless of whether it’s a mouth sore, bronchitis, or anything else. Infections are never a time to fool around.

This list of oral and topical herbal antibiotics is for informational purposes only. It is not meant for actual medicinal usage. Rather, the purpose of this list is simply to discuss these interesting properties seen in research. While some are being used for animals, you should discuss with a veterinarian first, before trying them on your cat, dog, or other pet.

1. Oregano oil

oregano leafIts use for chickens was mentioned above and in the laboratory, it has also been studied in mice.

Helicobacter pylori (H. pylori) causes stomach infections in two-thirds of humans worldwide (3). The side effects include peptic ulcers and even stomach cancer.

Published in 2016, researchers fed mice a 2:1 mixture of essential oils made from summer savory (Satureja hortensis) and oregano (Origanum vulgare) (4).

The results? In 70% of mice, this mixture was said to eradicate the pathogens. Given that H. pylori has many antibiotic resistant strains, they suggested:

“…this essential oil mixture has great potential as a new, effective, and safe therapeutic agent against H. pylori.”

Another study, this one being in vitro, tested oregano essential oil against 59 different bacterial strains. It was said to demonstrate varying degrees of effectiveness against all. The researchers claimed it “completely inhibits the growth of multidrug-resistant cystic fibrosis pathogens” which were tested in the experiment (5).

2. Mustard oil

mustard flowerOregano isn’t the only one on this list. Mustard seed essential oil also appears to work.

Because of a compound called allyl isothiocyanate, one in vitro study said it was “the most effective” when compared to oregano and thyme oils, which were all tested against foodborne pathogens (salmonella, staph, and listeria) (6).

In 2016, a discussion among doctors and scientists on respiratory infections took place in Frankfurt, Germany. This “expert panel” recommended the consideration of mustard oils as a possible future therapy (7).

The article summarizing the meeting, which was published in a medical journal, purported that “efficacy and safety of mustard oils had been confirmed for adults and children by several clinical studies.” [eg. B. Fintelmann V et al. Curr Med Res Opin 2012; 28: 1799-807; Goos KH et al. Drug Res 2006; 56: 249-57; Goos KH et al. Drug Res 2007; 57: 238-46]

Professor Ludger Klimek of Wiesbaden, Germany was quoted as saying:

“Especially in the early stages of inflammatory respiratory disorders, include herbal medicines for the treatment of first choice because, unlike synthetic chemical antibiotics, mustard oils have not only a single mechanism of action, but they act multimodal.”

It will be exciting to see in the future whether others will agree or not, after further research is done.

3. Cinnamon

ground cinnamonA search for the two words “cinnamon antibiotic” on PubMed yields over 100 results. Not only has it been studied extensively for having antibacterial properties on its own, but it has even been looked at for possibly combining with traditional antibiotics like doxycycline (8).

On its own, doxycycline is a type of tetracycline antibiotic commonly used for cystic acne, urinary tract infections, gum disease, and many others.

Cinnamon bark essential oil has been tested in lab experiments for things ranging from drug-resistant E. coli strains to possible benefits against Listeria on meat (9) (10).

Whether we will ever see this spice developed into actual treatments may be complicated by the fact that the most popular type, cassia cinnamon, is toxic to the human liver. Instead, perhaps the Ceylon variety might offer more potential for cinnamon benefits in healthcare.

4. Colloidal silver

So far everything discussed is a spice or a derivative of one. There are also minerals which have shown some promise in preliminary research. Perhaps the most talked about is silver.

What is colloidal silver? It is the suspension of microscopic silver particles in distilled water, which is created using electrolysis. It is sold as a dietary supplement.

chart of biomass size after colloidal silver treatment
The bar on the left (group 1) was treated with saline, while the other 4 bars were treated with topical colloidal silver solution in dosages ranging from as high as 30 ppm (group 2) to as low as 5 ppm (group 5).

A recent study involving sheep found that when compared to the control groups (non-treated), the groups given a topical colloidal silver solution “showed a significant decrease in biofilm biomass” from Staphylococcus aureus (11).

Even though they said that the study’s model “appears safe” it’s important to reiterate that this is unproven and may even have harmful side effects in humans. The FDA put out a consumer warning several years ago that silver dietary supplements might cause permanent skin discoloration (12).

Nearly a decade ago, there was an interesting report in a medical journal of using it colloidal silver on a 12 year old child with severe cystic fibrosis, but it is not approved for that nor any other medical use (13). A lot more research needs to be done on this mineral before it could even be considered as a candidate for treatment.

5. Goldenseal

Above we talked about a lady who claimed to use goldenseal for cats. That was one of the things covered a few years back in a segment on the Dr. Oz show about herbal antibiotic alternatives.

His guest was Dr. Pina LoGiudice ND, LAc, who said the following about this herb:

“Goldenseal has an active component in it called berberine, and how berberines work is it actually prevents bacteria from even adhering to our cell walls, so when you have a sore throat or even a strep throat, a great thing to do, what I always recommend to my patients, is making a gargle.”

On the show, her and Oz demonstrated a dosage using a pinch of salt and half a teaspoon of goldenseal, which was diluted in a glass of water. Their instructions said to gargle and spit, not swallow. Using it for a max of 2 weeks at a time.

goldenseal plantBoth Oz and the audience guest said what it tastes like is pretty bad, albeit in different words such as “moss” and “like if you swallowed sand from the beach.”

Bad flavor aside, is there any scientific evidence to substantiate the claim that goldenseal can prevent bacterial growth?

Laboratory experiments have suggested that when tested against strep (Streptococcus mutans), antimicrobial activity is seen from berberine, and to a lesser extent, two other compounds in goldenseal (6,8-di- C-methylluteolin 7-methyl ether and 6- C-methylluteolin 7-methyl ether) (14).

Because it has been used traditionally in herbal medicine for skin infections, researchers chose to study goldenseal against MRSA (Staphylococcus aureus) in an experiment and found (15):

“H. canadensis leaf extracts possess a mixture of constituents that act against MRSA via several different mechanisms.”

While not proven, goldenseal certainly appears to be a good candidate for future research given its characteristics.

6. Echinacea

What should you take for a cold? You often hear people say that Echinacea is a good herbal remedy to relieve the symptoms.

Since the common cold is a viral infection, antibiotics have no effect on it. What’s interesting about Echinacea is there have been studies suggesting it might be antibacterial and be a natural antiviral (16) (17).

echinacea flowerEchinacea, which is actually a type of daisy, is one of the most extensively studied herbs. PubMed shows over a thousand entries for it and if you filter those to just clinical trials, you get 83.

Regarding its potential as a natural antiviral supplement, the most interesting clinical trial is from 2012 simply due to the sheer size of it.

The goal was to see if it might help with cold prevention. Conducted by Cardiff University, 755 healthy people were given an Echinacea supplement or a placebo to take for a 4 month period. The researchers claimed:

“Echinacea reduced the total number of cold episodes, cumulated episode days within the group, and pain-killer medicated episodes.”

The difference was said to be a 26% shorter duration of illness. Recurrent colds were cut by 59% in the study. While it sounds great, the UK government’s NHS pointed out some major concerns they had about the study (18):

  • No results table was published
  • No estimates of error around measures of effect were reported
  • No declaration of funding
  • Only partial disclosure for conflicts of interest
  • Selective reporting of results

Do natural antibiotics work? While technically this study was looking at antiviral, the concerns expressed above are reasons why you have to really look past the headlines regardless of what a purported herbal cure or treatment may be. Even though it’s well studied, Echinacea remains unproven.

7. Andrographis

Grown in India and Sri Lanka, this is one you rarely hear about. Pina LoGiudice also talked about it in that same segment on the Dr. Oz show.

She said this traditional medicinal herb had been used for thousands of years, but…

“…now the clinical research is showing what a powerful anti-inflammatory and antibiotic andrographis is, especially for upper respiratory infections.”

Her recommended use to her patients was as a tea. Like the goldenseal, both the audience guest and Dr. Oz seemed repulsed by the taste, joking “I’ll take the capsule form.”

As of the time of publishing, a search on ClinicalTrials.gov for andrographis yielded 6 results, but 4 of those were for multiple sclerosis (MS), colorectal cancer, and rheumatoid arthritis.

Two involved acute respiratory infection but they were for blends of herbs, not as a stand alone.

Gaia Herbs Quick Defense ingredients labelOne was currently recruiting participants in China, sponsored by the China Academy of Chinese Medical Sciences. It involved a Chinese patented medicine using honeysuckle, forsythia, radix Isatidis, and andrographis paniculata (19).

Given the many misspellings and poor grammar, we’re not sure what to make of that one.

The second trial was completed, but the results had not been published. It involved Gaia Herbs Quick Defense over the counter dietary supplement, which consisted of (20):

  • andrographis paniculata leaf
  • ginger root
  • zingiber officinale
  • black elderberry
  • sambucus nigra

With no results published, no one knows how it performed.

As with the other ingredients on this list, it’s far too early to draw any kind of conclusions if andrographis works for respiratory infections. That being said, there have been a number of lab studies showing it has antibacterial qualities (21) (22) (23).

However it’s worth noting that if you go back to an earlier study in 1990, it was concluded that “anti-bacterial activity of AP [Andrographis paniculata] is undetectable in our study” (24).

8. Garlic

whole garlicRather than minerals like colloidal silver and disgusting exotic herbs like goldenseal, we finally come to a normal food on the list which people actually enjoy eating in abundance, regardless of whether or not any health benefit exists!

For the oregano essential oil, we talked about it being studied for H. pylori gastrointestinal infections. Garlic too has been evaluated for that (25) (26).

One study only involved 5 patients, but it said there was “no evidence” it worked to reduce or eliminate H. pylori (27).

A randomized clinical study involving 40 patients with denture stomatitis (DS) claimed better results for the group which used a garlic extract mouthwash when compared to nystatin, which is a prescription drug for fungal infections (28).

A common cause of food poisoning is Campylobacter jejuni, which is a type of bacteria. One study claimed promising results in the lab, but when they tried using garlic in water broilers to reduce C. jejuni growth, there was a small benefit seen but it was not statistically significant (29).

Another study tested garlic extract in the lab against strains of staph and E. coli and while it did have an antibacterial effect, “it is not potent like antibiotic Impinem” (which is an intravenous prescription antibiotic used for severe infections) (30).

In short, the evidence is even weaker for garlic being one of the antibiotic foods. Though perhaps there are compounds in garlic which someday might be useful, if they can be isolated and used in concentrated doses.

9. Coconut oil

coconut oilThis is one of the most overhyped superfoods. Many of its purported benefits are exaggerated or outright fabricated, as is the case with the stretch mark coconut oil treatment.

That being said, there is scientific research to suggest that a type of saturated fat in it might have antibacterial and antifungal properties. That fat is lauric acid (C12:0).

The list of foods high in lauric acid is quite short. Aside from coconut, there’s palm nut oil, cinnamon oil, and goat milk. Regular milk from a cow has it too, but about half the amount versus goat. The plant-based sources of lauric acid have exponentially higher amounts – coconut oil is best at 48%.

One study wanted to see if lauric acid would work topically as a natural antibiotic for acne bacteria (31).

To be clear, not all pimples are caused by bacteria and in fact, the exact causes of this skin condition are poorly understood. But for some instances of inflammation, the bacterium Propionibacterium acnes (P. acnes) has been singled out as a likely culprit.

The study only involved mice and Petri dish experiments, so it’s hard to read too far into it. Mice don’t even have pimples, so they had to use the same type of bacteria and monitor the mice for ear swelling and abscesses, which were locations where they applied the P. acnes bacteria.

acne, pimples on faceThey found both lauric acid and another saturated fatty acid, decanoic acid (capric acid), seemed to work for acne bacteria. However, it was the lauric acid which was said to have strong antibiotic activity both in the mice as well as the Petri dish. Whether that translates to a natural cystic acne treatment though is untested.

A double-blind controlled human study looked at using coconut and olive oils for atopic dermatitis/eczema (32).

That type of dermatitis causes itchy skin which is often red, swollen, and sometimes cracked. Staphylococcus aureus bacteria will use this compromised skin as a breeding ground, which only further worsens the side effects.

After 26 patients received one or the other oil for a period of 4 weeks:

  • 5% (1 patient) who had topically applied the virgin coconut oil still tested positive for Staphylococcus aureus.
  • 50% (6 patients) of those applying olive oil still tested positive.

Those findings, along with “broad-spectrum activity” against the bacteria in lab experiments, led researchers to conclude it might be useful in natural topical antibiotics, as a proactive treatment against atopic dermatitis colonization.

While not a bacteria, drug-resistant Candida species are a growing problem. Fluconazole, sold under the brand name Diflucan, is one treatment used for this type of fungus. When coconut oil was pitted against it in an experiment, the researchers found the coconut performed better for some species, such as Candida krusei (33).

Who knows, perhaps future research using humans will find coconut oil derivatives are useful as a natural antifungal for candida, as well as antibacterial purposes. We will have to wait and see. It would be interesting to see researchers test it on nail fungus.

10. Grapefruit seed extract

Here’s one you don’t hear much about, nor is there a great deal of research on it. But what you can dig up on it is fascinating.

grapefruitA University of Texas study pitted grapefruit seed extract against 5 commonly used topical antibacterial agents (34):

  • Bactroban
  • Nitrofurazone
  • Nystatin (mentioned above for denture stomatitis)
  • Silvadene
  • Sulfamylon

They tested these and the grape seed extract against 67 distinct biotypes in well plates. After being incubated overnight, they checked the plates and the extract was said to be “consistently antibacterial” against all and performed comparable to the proven topical ointments.

We’ve talked about a possible natural antibacterial for dogs, but how about bees? American foulbrood (AFB) is major problem for beehives. It can cause their destruction and the root of AFB is the spore forming Paenibacillus larvae.

A study concluded at least some forms of grapefruit seed extract could be used as a substitute for chemotherapeutic products, which are currently used for controlling the disease in beehives (35).

A small study involving 3 middle-aged men and 1 women took place in Nigeria. Each had a urinary tract infection (UTI) which tested positive for a different cause (36):

  • E. coli
  • Staphylococcus aureus
  • Pseudomonas aeruginosa
  • Klebsiella species

They were instructed to consume a dosage of 5 to 6 dried or fresh grapefruit seeds every 8 hours, for a period of 2 weeks.

All were said to respond favorably, with the exception of the man with P. aeruginosa. It was noted that his type of infection was antibiotic-resistant (gentamicin, tarivid, and augmentin failed). After using the grapefruit seed for 2 weeks, there was “reversal of the antibiotic resistance pattern.”

Obviously though, a lot more research needs to be done to find out if this may be a natural treatment for urinary tract infections, or any other type for that matter. You can’t say a non-controlled study of four people is evidence it can control bacterial infections!

11. Myrrh

Biblical magi on camels during starry nightWhen you hear of frankincense and myrrh, you probably think of the gifts the magi brought after the birth of baby Jesus. But that’s not the only time it’s mentioned in the Bible…

The Old Testament talks about camels who were loaded with balm and myrrh (Genesis 37:25). The Lord instructed Moses to use it as part of a sacred anointing oil (Exodus 30:23).

In the New Testament, Jesus was offered wine and myrrh before crucifixion (Mark 15:23) and then after, Nicodemus and Joseph of Arimathea brought it to wrap Jesus’ body (John 19:39):

“Nicodemus also, who earlier had come to Jesus by night, came bringing a mixture of myrrh and aloes, about seventy-five pounds in weight.”

Clearly, this myrrh holds significance, but what is it exactly?

raw myrrhThe Commiphora myrrha tree makes an aromatic resin, which is basically a natural gum. Also called African myrrh, it’s native to the Arabian peninsula and nearby countries in Africa, such as Ethiopia and Kenya.

At the open, we mentioned a lady claiming she used it in lieu of over the counter antibiotics for cats. Perhaps she is onto something, as there has been research in recent years suggesting it has antimicrobial activity.

In the lab, one compound in myrrh was found to have high activity against SA1199B, a strain of Staphylococcus aureus which is multidrug-resistant (37).

As far as myrrh essential oils, one study found them to have “moderate to high” activity against Gram-positive bacteria (38).

Another tested it against both Gram-positive and Gram-negative and found (39):

“considerable inhibitory effects against all tested organisms, except Pseudomonas”

One scientific review proposed the possibility of using it as an ingredient in acne vulgaris products (40).

In terms of wound healing, a study involving mice found that (41):

“Ointment formulations of both the oil and resin were found to be non-irritant at the concentrations used and showed significant increase in wound contraction rate, shorter epithelization time and higher skin breaking strength as compared to the negative control.”

They claimed the natural antifungal activity was comparable to the medication griseofulvin, while the antibacterial activity was comparable to ciprofloxacin.

A study which claimed to be “one of the most extensive on anti-virulence screenings” using 83 different essential oils claimed that myrrh – along with black pepper and cananga oils – demonstrate the most potential against Staphylococcus aureus (42). Perhaps in the future, compounds within these could be developed into new alternatives to antibiotics for some types of infections.

12. Manuka honey

Manuka honeyLast but not least, we circle back to this unique form of honey. As mentioned, the idea of using it for kennel cough in dogs and other veterinarian purposes had been proposed. What research is there to suggest that might work?

Actually, a fair amount.

There are over 200 research entries on PubMed about using Manuka honey for gingivitis, periodontal disease (43), dental plaque (44), neuropathic diabetic foot ulcers (45), sinus infections (46), and even MRSA (47), among others. Generally, they’re looking at it for topical uses.

During that segment on the Dr. Oz show about powerful natural antibiotics, the first one they talked about was using Manuka honey for cuts and scrapes. Oz closed the discussion by saying “this stuff is not just science fiction, it really does work.”

Having covered other pets, we can’t forget about alternative antibiotics for horses!

There was actually a clinical trial done involving eight adult horses and whether this honey would help with the healing of contaminated wounds (48). The results were mixed though. Even though the Manuka treatment group experienced a smaller wound area by reducing retraction, it did not change the overall healing time for those horses.

Going back to humans, a randomized study involving 108 patients with sloughy venous leg ulcers seemed to show a lot of promise (49).

After 4 weeks, MRSA was eradicated from 70% of the patients (7 total) treated with Manuka honey, compared to 16% (1 total) given hydrogel wound treatments.

There has been a lot of controversy about whether honey is better or the same for dental health versus refined sugar. A couple of years ago, a clinical study was done involving 30 children with a history of tooth infection or decay (50):

  • From 9 to 12 years old.
  • All had at least one decayed tooth.
  • 15 of the kids were given Manuka honey to use twice daily.
  • 15 of the kids did not get it. They were used as a control group.

The results? After being measured on day 10 and 21:

“Children using Manuka honey showed statistically significant reductions in salivary S. mutans”

Manuka flower
Manuka flower, photo credit: Forest & Kim Starr

Salivary Streptococci mutans are believed to contribute to cavities, tooth decay, and gum infection. For reducing colony counts, the researchers said Manuka might be an “effective adjunctive oral hygiene measure.”

Some herbal remedy websites claim that manuka honey heals cavities, but that is flat out wrong. Nothing can repair a tooth cavity, other than your dentist with a drill and filling.

While the honey’s purported medicinal uses come from topical and oral application, it is a delicacy which is quite in demand as a food.

People love the taste since it’s like regular honey, only stronger. Its unique flavor is because the bees make it using Manuka flower nectar, a flowering tree which is only native to New Zealand.

It’s not cheap and it’s hard to find in stores, but it’s definitely worth trying this tasty sweetener.

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.