Although research suggests essential oils may have some health benefits, it is important to remember that the Food and Drug Administration (FDA) does not monitor or regulate the purity or quality of these oils. A person should talk with a healthcare professional before using essential oils and research the quality of a particular brand’s products. It is also important to always do a patch test before trying a new essential oil.

Oregano is an herb belonging to the mint family. Oregano oil is an extract that people derive from the plant. While oregano may help a cold, there is insufficient evidence to suggest that it can cure a cold.

Research suggests that some of the chemicals in oregano have antiviral properties. Scientists have, therefore, speculated that oregano oil might be an effective remedy against cold and flu viruses. However, at present, there is not enough research to support this idea.

People may use the term oregano oil to refer to either oil of oregano or oregano essential oil. The two are very different in their uses and applications.

This article outlines the scientific research into oregano essential oil and its efficacy as a treatment for the common cold. We also outline some potential risks of using oregano.

a bottom of oregano oil which may be used for treating a coldShare on Pinterest
Several chemicals within oregano could potentially help treat symptoms of a cold.

Oregano is an herb belonging to the mint or Lamiaceae family. It is native to Western and Southwestern Eurasia and the Mediterranean.

People may use the term oregano oil to refer to either oil of oregano or oregano essential oil. The two are very different things.

It is important to note the difference between oregano essential oil and oil of oregano.

Oil of oregano is an oil that people extract from the leaves of the oregano plant. It is available in the form of consumable capsules or a liquid.

Oregano essential oil is a much more concentrated substance than oil of oregano.

Manufacturers typically use heat to extract the oil from the leaves, stems, or flowers of the plant. Unlike oil of oregano, it is not safe to consume oregano essential oil.

People should only use oregano essential oil in aromatherapy or to apply topically with a carrier oil.

Researchers have identified several different chemicals in oregano that may help fight viral or bacterial infections, or otherwise promote health. These include:

  • carvacrol
  • thymol
  • terpenine
  • cyamine

Some research suggests that different types of oregano may have higher concentrations of certain chemicals. For example, wild oregano tends to have more carvacrol and thymol.

To date, there is very little research into oregano, and different studies have looked at different varieties of the herb. As such, there is not enough evidence to suggest whether one variety offers greater benefits than another.

A small number of studies have investigated whether oregano essential oil offers promise as a treatment for the common cold. The findings are limited, and they do not provide much support for the use of oregano essential oil in treating a cold.

A couple of studies investigated the antiviral properties of oregano essential oil in a laboratory setting. A separate study investigated whether oregano essential oil alleviates the symptoms of upper respiratory tract infections (URTIs) in people. This article outlines the key findings of these studies below.

The studies also look at oregano essential oil rather than oil of oregano. As a result, the findings do not necessarily apply to this different form of oregano oil.

Antiviral properties

A 2019 laboratory study investigated the antiviral properties of an essential oil blend of oregano, thyme, and salvia. The researchers tested the effectiveness of the oil blend against the following respiratory tract viruses:

The essential oil blend was not effective against RSV or adenovirus 5. However, it did show strong antiviral activity against rhinovirus, and two out of three strains of influenza.

However, this study investigated the oils in a test dish and not a human body. As such, it is unclear whether the blend would kill a cold or flu virus in a person.

While the 2019 study found that essential oregano oil in a blend was not effective against adenovirus 5, a 2016 review notes that it may be effective against adenovirus 3.

Adenoviruses cause a range of illnesses, including sore throat, and other cold-like symptoms.

Alleviating symptoms

An older and small 2011 study investigated the efficacy of an aromatic essential oil spray as a treatment for URTIs. The aromatherapy spray contained a blend of the following oils:

One group of 26 participants used the spray five times per day for 3 days. A separate group of 34 participants used a placebo spray.

Twenty minutes after treatment, the participants who used the spray reported greater symptom relief than those using the placebo. After 3 days, there were no significant differences in symptoms between the two groups.

The findings suggest that the essential oil blend may offer rapid symptom relief, but it will not necessarily speed up healing or cure a viral infection.

The ways to use oregano essential oil and oil of oregano are very different.

Oregano essential oil

People who wish to try using oregano essential oil can use it in aromatherapy or apply it topically with a carrier oil.

Before using it for the first time, a person should dab a few drops of diluted oil onto a patch of skin on their forearm and apply a bandage over the top for 24 hours. If there is no irritation or discomfort during this time, it should be safe to use a diluted form of the oil.

People must never swallow essential oils or ingest them in any other way.

Oil of oregano

One way of using oil of oregano is to add 2–3 drops to water or juice and drink the mixture. However, people should be careful to use oil of oregano and not oregano essential oil. The latter is much stronger and is not safe to consume.

Alternatively, people may want to try oil of oregano supplements.

When using herbal supplements, people must follow the instructions on the package carefully.

Oil of oregano and oregano essential oil may not be suitable for everyone. Some potential risks and side effects are outlined below.


People who have allergies to plants in the Lamiaceae family should not use oregano oil. Other plants belonging to this family include:


According to Alberta Rheumatology, oil of oregano may reduce the ability of blood platelets to clump together, thereby increasing the risk of bleeding.

People who are awaiting surgery should stop taking oregano oil 2 weeks before their procedure. This will reduce the risk of a bleed during or after surgery.

People should also be aware that oregano oil may increase the effect of blood thinning or anticoagulant medications. Therefore, people who take warfarin, heparin, or other anticoagulant medications must avoid taking oregano oil.

Changes in lithium metabolism

Oil of oregano may change the way that the body metabolizes lithium. People who take lithium should avoid taking oil of oregano.

A person who wants to take both products should talk to their doctor first, as they will require regular health monitoring.

Changes to blood sugar

Oil of oregano may lower blood sugar levels.

A person must talk to a doctor before using oil of oregano if they have low blood sugar or take diabetes medications to control their blood sugar levels.

Several other plant essential oils show promise for relieving viral symptoms, such as the common cold.

The chemical carvacrol in oregano is also present in thyme, pepperwort, and bergamot. These herbs may offer some of the same antiviral and antimicrobial effects as oregano essential oil.

People may also be interested in using herb essential oils to alleviate the symptoms of the common cold.

The following list outlines the herb essential oils that scientists have shown to be effective in combination with oregano essential oil:

  • thyme
  • salvia
  • rosemary
  • eucalyptus
  • peppermint

Peppermint and eucalyptus essential oils are particularly useful for easing congestion.

There are very few studies that investigate the efficacy of oregano essential oil as a treatment for the common cold.

A couple of studies have shown that oregano essential oil kills certain cold and flu viruses in a laboratory setting. A separate study has shown that it may alleviate cold-like symptoms in people.

In all, there is insufficient evidence to suggest that oregano can cure a common cold. However, a person could use it in combination with other treatments to help alleviate the symptoms.

People should take care when choosing oregano products. Oil of oregano is usually safe to consume, while oregano essential oil is stronger and is not safe to consume.

People who take prescription medications should talk to a doctor before taking oil of oregano or any other type of herbal supplement.