Oregano Oil: 6 Major Side Effects You Must Know

Written by Ravi Teja Tadimalla, Professional Certificate In Food, Nutrition & Health

The side effects of oregano oil may make you reconsider using it. It is an essential oil extracted from the Italian herb oregano. While the herb is commonly used in various recipes, the essential oil is renowned for its antimicrobial qualities (1).

Oregano oil contains several beneficial chemical compounds. However, it can produce some unpleasant side effects when taken in excess. This article examines the side effects of oregano oil and potential drug interactions. Read on.

What Are The Side Effects Of Oregano Oil?

Oregano oil may cause skin allergies in certain individuals. It may also lead to gastric distress and hypoglycemia. Some reports suggest that the oil can also cause miscarriage and must be avoided by pregnant women.

1. May Cause Allergies

Though oregano oil is usually well-tolerated, it can cause skin allergies in certain individuals (2). These effects could be more pronounced in oregano oil supplements as such products do not require strict approvals by the US FDA (Food and Drug Administration).

Individuals allergic to plants in the Lamiaceae family tend to be allergic to oregano as well. The other plants in this family include basil, marjoram, sage, mint, and lavender (3).

In some people, oregano oil can also cause skin irritation in concentrations as low as 3-5%. Inhaling the oil may not have such effects (4).

2. May Cause Gastric Distress

Intake of oregano oil may lead to gastrointestinal distress (2). However, there is very limited research as to why that occurs. Hence, please consult your doctor before ingesting the oil.

3. May Lead To Hypoglycemia

The carvacrol in oregano oil could be responsible for this effect. In rat studies, it was found to show reductions in serum glucose levels (5). Though this could be good news, individuals who are already on medications to lower blood sugar may experience hypoglycemia (excessively low blood sugar levels).

Oregano oil may also be one of the few essential oils that can impact glucose sensitivity (6). If you are already on diabetes medications, oregano oil may further accentuate the effects.

4. May Cause Miscarriage


A herbal infusion containing oregano was reported to cause abortions in pregnant women (7). The herbal infusion contained various other ingredients too, so it was hard to determine if oregano was the sole culprit.

Other reports also discuss the possibility of herbal infusions causing miscarriage. Also termed as herbal abortion, it is a process involving the consumption of a series of herbs to induce miscarriage deliberately (8). Oregano oil may be one such herb.

There is less research directly linking oregano oil to miscarriage. However, please exercise caution as the oil may have abortifacient effects (9).

5. May Lead To Cardiac And Respiratory Collapse

Oregano contains another compound, thymol, which may lead to cardiac and respiratory collapse. The compound may also lead to central hyperactivity, convulsions, and even coma. Though these effects are rare, it is important you be aware of them (10).

6. May Interact With Certain Drugs

Given its hypoglycemic effects, oregano oil might interact with diabetes medications. There is no research to support this, though. If you are taking diabetes medications, please check with your doctor before you consume oregano oil.

Oregano oil may also interfere with the absorption of zinc, iron, and copper. Those taking these supplements must consult their doctor before ingesting oregano oil. There is very little research to support this.

There is no doubt oregano oil is beneficial to human health. But taking it in excess can have detrimental effects.

What Is The Ideal Dosage Of Oregano Oil?

There is very less information available about the ideal dosage of oregano oil. Most supplements and essential oils have dosages specified by the manufacturers. These dosages take into account the oil’s most potent compounds, including thymol and carvacrol.

Please do not exceed the dosage specified on the container. If you are looking for the ideal dosage for yourself, please consult your doctor.

Also, there is limited information on if you can actually ingest oregano essential oil. Do check with your health care provider. Some sources state that you must take a week-long break after using oregano oil every three weeks. The evidence backing this up is not solid. Your health care provider must be able to guide you better.

When Should You Visit A Doctor?

As discussed, there is less information on the safety of oregano oil upon ingestion. If you experience any of the following symptoms, please visit your doctor:

  • rashes
  • headaches
  • fatigue
  • stomach distress
  • difficulty swallowing
  • muscle pain

The best way to avoid these symptoms is to consult your doctor. Also, the oil is available in most health stores. Remember to go for a reputed brand and follow the manufacturer’s instructions.

Oregano essential oil is renowned for its natural antimicrobial properties. However, overconsumption can lead to a number of problems. The side effects of oregano oil range from causing gastrointestinal issues to possibly lowering blood sugar levels. It may lead to heart or respiratory problems as well. In some cases, oregano oil may trigger allergic reactions or interfere with the functioning of certain medications, especially those for managing diabetes. If possible, try to limit your intake or stay away from it entirely to avoid such complications.

Frequently Asked Questions

Can you take oregano oil with antibiotics?

There is less information focusing on the possible interactions oregano oil may have with antibiotics. Please consult with your doctor.

How long can you take oregano capsules?

You can take the capsules every day. Sticking to the right dosage is key. Also, check for any adverse reactions you may face.


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