Oil of Oregano: Can It Really Prevent a Cold?

Disclaimer: Results are not guaranteed*** and may vary from person to person***.

Oil of oregano
Credit: Rawf8

Reviewed by Dr. Michael Kessler, DC

What Is Oil of Oregano?

Oil of oregano, also called oregano oil, is a herbal supplement most commonly used to prevent or treat certain respiratory illnesses. There are some folks out there who swear by oil of oregano for cold prevention, while it’s also used for cold and flu symptom treatment.

Much of the information on oil of oregano’s benefits is anecdotal, yet there is some scientific research indicating it may exhibit antiviral and antibacterial effects.

You probably know of oregano (Origanum vulgare) through cooking. If you like Italian food, you’re certainly well-acquainted with the small, bushy herb with a slightly minty flavor (which also happens to belong to the mint family). But aside from its taste, oregano features high levels of compounds that are known to have antiviral, anti-inflammatory, antimicrobial, and antioxidant effects. These compounds are extracted from the leaves and stems of the plants and cold-pressed into oil for medicinal purposes.

It should be noted that oil of oregano’s uses are different from those of highly concentrated oregano essential oil. Essential oils should never be ingested to treat cold, flu, or other respiratory-related symptoms.

How Effective Is Oil of Oregano for Colds?

The effectiveness of oil of oregano for colds is unknown, and ultimately, it depends on whom you ask. For example, I know people who take it daily during cold and flu season and believe it plays an instrumental role in protecting them from catching a cold. And that it’s not playing a role becomes harder to argue if they’re noticing fewer colds and symptoms, even when people in their own household take ill!

On the other hand, there is currently no substantial scientific research to definitively confirm that it helps keep cold and flu symptoms at bay. There are lab studies and small-scale human studies that show benefits, and the outcomes are quite promising. The reality is that more research needs to be completed before we know if the oil is really effective.

Active Compounds in Oil of Oregano

The active compounds recognized for oil of oregano’s potential health benefits are carvacrol, thymol, and other terpenes.

Carvacrol is the main active compound in oregano oil. It is a type of phenol that is known as a potent antibacterial, and studies have shown it can inhibit both human and animal viruses in an in vitro setting. What’s interesting is that, with respiratory viruses, this inhibition was even more pronounced when using oregano oil compared to isolated carvacrol. This is likely due to the other active compounds in oil of oregano, like thymol.

Thymol is another abundant phenol in oregano oil, yet it is available in greater amounts in thyme. That said, it can still contribute to possible oregano oil benefits. Thymol may help protect against bacterial, viral, and fungal infections as an antimicrobial agent.

Terpenes are known to exhibit antibacterial and antioxidant activity in general. It’s possible that these compounds work together to fight against infection or provide reinforcement to the immune system as a preventative measure. Although the advantages of taking oil of oregano daily to avert colds lack any scientific evidence, there is some research showing oregano oil may be worthwhile in controlling symptoms once they’ve appeared.

One study published in the journal Evidence-Based Complementary and Alternative Medicine showed that people using a throat spray featuring oregano oil, peppermint oil, eucalyptus oil, and rosemary oil were able to quell symptoms within 20 minutes of spraying. Participants reported reductions in throat soreness, hoarseness, and coughing compared to a group taking placebo.

Antioxidant Activity

Studies have found that oregano packs a serious punch when it comes to antioxidant content. Research published in the Journal of Agricultural and Food Chemistry reported that the herb had the highest antioxidant concentration of nearly 40 culinary and medicinal herbs.

Antioxidants are believed to keep the body healthy by neutralizing the damage caused by free radicals. A product of oxygen metabolism, these unstable molecules may contribute to a variety of illnesses and chronic diseases.

With an ORAC of 21,035 per tablespoon, the dried herb easily beats out powerhouses like walnuts (1,626/tbsp) and blueberries (561/tbsp). This antioxidant content is concentrated in oregano oil.

Overall, if oregano oil is a product you firmly believe in and have experienced some benefit while using (under the guidance of a medical professional), there is little risk and therefore little reason to stop. Though conclusive evidence on efficacy is lacking, it doesn’t appear to be harmful.

Of course, central to cold prevention is building up your immune system by eating plenty of nutrient-rich vegetables and fruit, and making sure your hands are washed regularly to prevent the spread of germs.

How to Use Oregano Oil for Colds

If you want to use oil of oregano for colds, there are a few things you need to be aware of. The first is that it is considered a nutritional supplement and therefore is not regulated by the government for purity or efficacy. That means you will want to select brands from trusted manufacturers and read ingredient labels.

Oil of Oregano

The most common way to take oil of oregano is as a gel capsule or tincture. Droplets of tinctures are usually administered under the tongue or down the throat, while capsules are swallowed whole. The products may cause some burning or irritation, and may lead to some burping that smells, unsurprisingly, like oregano.

Because products will be dosed differently and may have varying concentrations, it’s difficult to recommend exactly how much to take for a given benefit. The best method to follow is what is outlined on the bottle, and make slight adjustments as deemed necessary. For example, dosing for oil of oregano tinctures to treat cold symptoms can range anywhere from three to 20 droplets.

Oregano Essential Oil

Oregano essential oil should never be ingested, so if you want to buy a tincture, be absolutely certain that it is not oregano essential oil. The high concentrations of essential oils are not safe to ingest under any circumstances. If you have oregano essential oil, dilute with water to use it through either a diffuser or steam inhaler to relieve symptoms like a runny nose or stuffed sinuses.

Oregano Oil Side Effects and Precautions

Provided you don’t accidentally ingest oregano essential oil, oregano oil is safe for most people and doesn’t have many worrisome side effects. Those who don’t particularly like the taste of oregano may experience some unpleasantness upon ingestion, but that is the biggest risk for the general population.

That said, there are certain groups that might experience adverse effects to oil of oregano. Those groups include:

  • People who are allergic to mint, sage, basil, or lavender (and, of course, oregano)
  • Pregnant or breastfeeding women
  • Children
  • People with bleeding disorders or those taking medication to alter blood clotting

Final Thoughts on Oil of Oregano for Colds

It’s important to remember that there is a lack of consistent and credible science to support oil of oregano as a treatment for colds. It may be effective in managing symptoms, but should be used as more of a complementary therapy than a central tenet of your prevention or treatment approach.

Start with including more fruits and vegetables in your diet and being conscious of handwashing. Also, the oil should not serve as a substitute for treatment recommended by a doctor, especially if it is being used for flu symptoms.

Article Sources (+)

Cronkleton, E., “Oregano Oil for Cold and Flu: Does it Work?” Healthline, March 6, 2018; https://www.healthline.com/health/oregano-oil-for-cold, last accessed March 1, 2019.
Pilau, M., et al, “Antiviral activity of the Lippia graveolens (Mexican oregano) essential oil and its main compound carvacrol against human and animal viruses,” Brazilian Journal of Microbiology, Oct.-Dec. 2011; 42(4): 1616–1624; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768712/, last accessed March 1, 2019.
Eran, B., et al, “Treatment of Upper Respiratory Tract Infections in Primary Care: A Randomized Study Using Aromatic Herbs,” Evidence-Based Complementary and Alternative Medicine, 2011; 2011: 690346; https://www.hindawi.com/journals/ecam/2011/690346/, last accessed March 1, 2019
Pawlowski, A., “Can Oregano Oil Boost Your Health?” Today, January 25, 2018; https://www.today.com/health/oregano-oil-health-claims-experts-weigh-t121728, last accessed March 1, 2019.
Johnson, J., “What are the benefits of oregano oil?” Medical News Today, January 16, 2019; https://www.medicalnewstoday.com/articles/324203.php, last accessed March 1, 2019.
Georgetown University Medical Center, “Oregano Oil May Protect Against Drug-Resistant Bacteria, Georgetown Researcher Finds” Science Daily, October 11, 2001; https://www.sciencedaily.com/releases/2001/10/011011065609.htm, last accessed March 1, 2019.
“Help Ward Off Infections and Improve Your Immune System With Oregano Oil,” Mercola, July 7, 2016; https://articles.mercola.com/herbal-oils/oregano-oil.aspx, last accessed March 1, 2019.
Rowles, A., “9 Benefits and Uses of Oregano Oil,” June 16, 2017; https://www.healthline.com/nutrition/9-oregano-oil-benefits-and-uses, last accessed March 1, 2019.
“Table-ORAC (Antioxidant) Value of Spices and Herbs,” Brain Wellness; http://brainwellness.com/nutrition/memory-preservation-nutrition/useful-food-facts/orac-and-anti-oxidant-values-of-spices-and-herbs-and-chocolate/table-orac-antioxidant-value-of-spices-and-herbs/, last accessed March 1, 2019.