Oregano Oil: 6 Major Side Effects You Must Know

Consuming too much of this fragrant oil may cause more pain than gain.

Medically Reviewed by Serena Benali, RDN
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, when taken in excess, it can produce some unpleasant side effects. This article examines the side effects of oregano oil and potential drug interactions. Read on.

What Are The Side Effects Of Oregano Oil?

Woman experiences skin irritation as a side effect of using 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 Skin Irritation

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

Woman experiences gastric distress as a side effect of using oregano oil


Although rare, 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

Carvacrol a strong antioxidant compound in oregano oil, could be responsible for its ability to reduce blood glucose levels. In an animal study, it was found to show reductions in blood glucose levels (5). Though this could be good news, individuals who are already on medications to lower blood sugar must consult a doctor before consuming oregano oil or its supplements.

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 Have Abortifacient Effects


A herbal infusion containing oregano was reported to induce abortions in pregnant women (7). The herbal infusion contains various other herbs in large amounts.

Many anecdotal evidence suggests that herbal infusions may cause miscarriage. Termed the herbal abortion, it is a process involving the consumption of a series of herbs to induce a 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

Oregano oil may interact with diabetes medication


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.

Many anecdotal evidence suggests that 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?

Woman pouring a few drops of oregano oil into a bowl


There is little 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.

Do not exceed the dosage specified by the manufacturer. 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?

If you experience any of the following symptoms, please visit your doctor:

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

Infographic: Major Side Effects Of Oregano Oil

Oregano oil is an essential oil better known for its antimicrobial properties. It contains several beneficial chemical compounds that help treat many ailments. However, it may cause some negative reactions in some people. Check out the infographic below to learn about the major side effects of oregano oil.

major side effects of oregano oil [infographic]

Illustration: StyleCraze Design Team

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

Overconsumption of oregano oil 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 and in some cases, may trigger skin irritation. 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?

Consult a doctor to learn more about the frequency and dosage as it may differ from person to person. Moreover, excessive consumption may lead to side effects. Therefore, do not self-medicate.


Articles on StyleCraze are backed by verified information from peer-reviewed and academic research papers, reputed organizations, research institutions, and medical associations to ensure accuracy and relevance. Check out our editorial policy for further details.

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Ravi Teja Tadimalla is an editor and a published author. He has been in the digital media field for over... more

Serena Benali

Serena Benali is a Registered Dietitian and founder of In Good Nutrition. Before opening the doors to her private practice,... more