Oregano oil is an herbal supplement that’s known for its antiviral, anti-inflammatory, and antioxidant properties. It contains several potentially healing compounds, such as carvacrol, thymol, and terpinine.

People have traditionally used it for respiratory health, and it’s also become a popular alternative remedy for cold and flu symptoms.

You can find it at most health food stores as a tincture or softgel capsule. You can also buy it in the form of a highly concentrated aromatic, volatile (tending to evaporate) essential oil for external use and aromatherapy.

Keep reading to learn more about the research behind the benefits of oregano oil for cold and flu symptoms and how to safely use it.

There have been several recent studies looking at the health benefits of oregano herbal oil, and most of the findings are promising.

A 2017 study found that oregano oil, especially from the leaves of an oregano plant, had strong antioxidant properties. The researchers noted the traditional use of oregano oil in treating fevers and respiratory symptoms, which are both associated with the flu.

Laboratory research from 2011 found that oregano oil can inhibit both human and animal viruses in vitro. The researchers noted that this action is likely due to carvacrol, one of the main compounds in oregano oil. While carvacrol was more effective against certain viruses on its own, oregano oil was more effective against respiratory viruses, such as flu viruses.

Participants with upper respiratory infections in a 2011 study used a throat spray containing oregano oil as well as diluted eucalyptus, peppermint, and rosemary essential oils. They used it five times a day for three days.

Compared to participants in the placebo group, those who used the spray had reduced symptoms of sore throat, hoarseness, and cough 20 minutes after using it. However, there wasn’t a major difference in symptoms between the two groups after three days of treatment. The researchers noted that this might be due to symptoms naturally improving in both groups during those three days.

In addition, a small 2013 study found that oregano oil reduced pain in rats due to its analgesic effects. This suggests that oregano oil might help more painful flu symptoms, such as body aches or a sore throat, but larger human studies are needed.

Oregano oil is generally safe to use, but it can have some side effects.

Avoid using it if you’re allergic to mint, sage, basil, or lavender. If you’re allergic to any of these, you’re likely allergic to oregano as well.

Don’t use oregano oil if you’re pregnant or breastfeeding.

Talk to your pediatrician before using it on a child.

Don’t take oregano oil if you have a bleeding disorder or are on any medications that alter clotting of your blood.

Supplements and herbs aren’t closely monitored by the FDA, and there may be issues regarding such attributes as purity, contamination, quality, and strength. Research the brand and be an informed consumer. It’s always wise to talk to your physician before using any herb or supplement.

Even if you don’t have an allergy, taking oregano oil may cause:

  • nausea
  • vomiting
  • diarrhea
  • stomach problems
  • fatigue
  • increased bleeding
  • muscle pain
  • vertigo
  • headache
  • difficulty swallowing
  • excessive salivation
  • inappropriate talkativeness

Read more about the side effects of oregano oil and when you should see a doctor.

There are several ways to use oregano oil.

Never ingest essential oils. Instead:

  • You can add a few drops to a steam diffuser or bowl of hot water.
  • You can also apply it to your skin after adding about five drops to a carrier oil, such as coconut oil.

Learn more about how to use essential oils for the flu.

You can also look for an oregano oil tincture, which is not a volatile essential oil and is safe to take orally. It’s also called an herbal oil. Follow the dosage instructions on the bottle.

Alternatively, you can take up to 150 milligrams of oregano herbal oil in capsule form. You can also divide this amount into three to four doses and take it throughout the day.

Regardless of why you’re taking oregano oil, make sure you take at least a week-long break for every three weeks of use.

Oregano oil is a powerful substance, so it’s best to start with the smallest possible dose to see how your body reacts. You can slowly increase the amount you take once you see how your body responds.

Just make sure you don’t take more than the recommended amount listed on the package. Also keep in mind that recommended doses can vary between manufacturers.

Oregano oil has several health benefits that are backed by research, though larger studies are needed to fully understand how it works.

If you find yourself fighting a cold or flu, try using oregano herbal oil for relief. Just make sure you don’t go over the recommended dose.