Unlike the herb you cook with, commercially-prepared oregano oil is highly concentrated and should be diluted before use. Side effects can include nausea, vomiting, gastric distress, and hyperactivity.

You may already know that oregano is an Italian herb commonly used in cooking. But it can also be made into a more concentrated herbal supplement, often called oregano oil. There are also oregano essential oils which have a much stronger concentration of the oregano plant than the herbal supplement.

Oregano essential oil is made from the leaves of the oregano plant. Even though oregano is a well-known herb found in many kitchens, oregano herbal oils and oregano essential oils aren’t used for cooking. Rather, the essential oil is used both topically and through inhalation to treat specific health conditions. The herbal oil can be taken as an herbal supplement.

Oregano oil contains chemical compounds, including phenolic glycosides (phenols). These compounds have antioxidant and antimicrobial properties. Phenols, such as carvacrol, cymene, terpinine, and thymol, account for much of the composition of oregano oil. It’s the phenols in oregano oil which may make it beneficial.


Oregano oil extract is an herbal supplement. It’s available in supplement form, as a pill, and as a softgel capsule. These usually contain other ingredients to dilute oregano oil, since it’s very potent. The capsules can be taken orally, or cut open and applied to the skin, provided they’re not full strength.

Oregano oil is also available as a highly concentrated essential oil that comes in liquid form. The oil may come premixed with a carrier oil or it may be purchased full strength. If it’s not premixed, you’ll have to dilute it yourself by combining it with a carrier oil, such as coconut or olive oil. The usual recipe is 5 to 6 drops for every ounce of carrier oil.

The essential oil can be used topically after it’s diluted. Don’t take any essential oil orally without seeing a certified aromatherapist first. Some essential oils are toxic and qualities vary.

Oregano essential oil can also be used in steam, as a vapor to be inhaled. This is done by putting one or two drops in a vaporizer or bowl of steaming water.


Most of the research done to date on oregano has been in the form of in vitro laboratory studies, animal studies, or small human trials. While much of this research is promising, it’s by no means definitive proof that oregano oil is effective. Even so, this product is marketed for many uses.

Use the herb in cooking or an herbal supplement for:

Use the essential oil as a vapor for:

Use the diluted essential oil topically for:

Unlike the herb you cook with, commercially-prepared oregano oil is highly concentrated. It’s easy to take too much or to use it for too long. When used as directed, oregano oil should be safe. In too-high doses, it may have detrimental effects.

This may be due in part to thymol, one of the phenols it contains. In high doses, thymol is a mild irritant which might affect the skin or internal organs. It can cause:

  • nausea
  • vomiting
  • gastric distress
  • central hyperactivity (inappropriate talkativeness)

Thymol may also be irritating or corrosive to the skin and eyes. Oregano oil should never be applied to broken skin or used on or near the eyes.

Oregano oil may cause an allergic reaction in some people. If you’re allergic to oregano or to other plants in the Lamiaceae family, such as mint, sage, basil, and lavender, don’t use oregano oil.

When used topically, diluted oregano essential oil may cause a skin rash, even in people who aren’t allergic to it. It’s important to check with your doctor before using oregano oil and to follow package directions exactly, whether you’re using the capsules or essential oil.

There’s been no medical research done on oregano oil’s safety for children, or for pregnant or breastfeeding women. These populations shouldn’t use oregano oil. While data is lacking, there’s some concern that oregano oil may cause uterine contractions or miscarriage.

Medicinal dosages of oregano oil for people hasn’t been studied in-depth. Commercially-sold supplements and essential oils have recommended doses, established by their manufacturers. These take the amount of thymol and other phenols into account.

It’s important not to exceed the recommended dosage given or to take oregano oil in any form, including on the skin, for more than several weeks. When using oregano essential oil, a little goes a very long way.One to two drops of diluted oil may not seem like much, but exceeding that dosage may cause adverse reactions to occur.

Symptoms of oregano allergy can include rash, stomach distress, or trouble breathing. It’s especially important not to inhale oregano oil if you might be allergic to it. Doing so can cause inflammation of the airways and might quickly become dangerous.

Chronic exposure to thymol may cause symptoms warranting a doctor’s visit. These include:

There are many claims about oregano oil’s ability to soothe symptoms and cure medical conditions. However, there’s very little evidence to back up these claims.

If you decide to take oregano oil, either in supplement or essential oil form, make sure to follow dosage directions exactly and to check with your doctor prior to use. Remember that essential oils are much stronger than the supplements and should always be diluted. Oregano oils shouldn’t be used in babies or children, and pregnant or breastfeeding women.