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Oregano is an herb that's commonly used in cooking. Oil extracted from its leaves has a long history of medicinal uses.

Over the centuries, it has been used to treat a variety of ailments, including snake and spider bites, respiratory troubles, and menstruation problems. Today, it is marketed for the treatment of a long list of health conditions.

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Why do people take oregano oil?

There are many claims about the uses of oregano oil. But there is little evidence to suggest that it is effective for any condition.

For example, oregano oil is often marketed for the treatment of intestinal parasites and the symptoms that go with it, such as:

  • Bloating
  • Cramping
  • Constipation
  • Diarrhea
  • Fatigue

A single study found that taking 200 milligrams of oregano oil three times a day for six weeks eliminated three such parasites. But the study was small, inconclusive, and was funded by a supplement manufacturer.

Some laboratory studies show that oregano or its components have properties that can kill some food-borne germs. But there is no evidence that it helps prevent food poisoning.

Oregano oil has also been used to treat a condition that some alternative medicine practitioners refer to as yeast hypersensitivity syndrome. In this condition, an excess of the yeast candida albicans is thought to cause symptoms, such as sinus congestion, headache, fatigue, and depression. It is not a condition that is recognized by conventional medicine. And there is no evidence that oregano oil helps treat these symptoms.

Oregano oil in an oral form is also used to try to treat respiratory tract conditions such as:

  • Coughs
  • Asthma
  • Croup
  • Bronchitis

Oregano oil is also marketed as an aid for:

  • Urinary tract infections
  • Indigestion
  • Heartburn

Oregano oil, when put into a form that lets it be applied to the skin, has been used to try to treat:

  • Acne
  • Athlete's foot
  • Dandruff
  • Warts
  • Gum disease
  • Toothaches

Marketers of oregano oil claim a host of other applications as well.

There is no research to back up these health claims.

Optimal doses of oregano have not been set for any condition. Quality and active ingredients in supplements may vary widely. This makes it very hard to set a standard dose.

Can you get it naturally from foods?

Oregano leaves can be steeped in hot water and prepared as a tea.

What are the risks of taking oregano and oregano oil?

Experts agree that oregano is safe when used for its intended purpose -- adding flavor to food. Oregano's safety for medicinal purposes is not known.

Due to some of its properties, a few things should be kept in mind when taking oregano or oregano oil in medicinal amounts.

  • In large doses, oregano oil may be toxic.
  • Oregano may have diuretic effects.
  • Large amounts of oregano can upset the stomach.

Pregnant women should not take oregano in medicinal amounts because it may cause miscarriages. And people taking lithium should avoid oregano.

People should also avoid oregano if they have allergies to certain herbs such as:

  • Basil
  • Lavender
  • Hyssop
  • Marjoram
  • Mint

Be sure to tell your doctor about any supplements that you take, even those that are labeled "natural."

WebMD Medical Reference

Reviewed by Melinda Ratini, DO, MS on December 07, 2012

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