Oil of oregano is not considered safe to take during pregnancy. In concentrated supplement form, oregano oil is classified as an abortifacient, meaning it can induce miscarriage, and major health institutions advise against its use by pregnant women. This applies to oregano oil capsules, liquid supplements, and essential oil, though small amounts of dried oregano used as a seasoning in food are not a concern.
Why Oregano Oil Is Risky During Pregnancy
The concentrated compounds in oregano oil have been shown to be embryotoxic in animal studies. When pregnant mice were given oregano oil orally for two weeks, researchers observed a significant increase in embryonic cell death. While no controlled human trials exist (for obvious ethical reasons), the animal evidence is concerning enough that the National Institutes of Health explicitly labels oregano in supplement doses as an abortifacient that should not be used during pregnancy or by women of childbearing age not using effective contraception.
Real-world poisoning data supports this classification. A review of 86 cases reported to the Uruguayan Poison Control Center over three years involved women who ingested herbal products with abortive intent during the first trimester. Oregano appeared among the plant species used in a multi-ingredient abortifacient product. Of the 86 cases, 23 resulted in abortion and 6 were fatal.
Cooking With Oregano Is Different
There is an important distinction between sprinkling dried oregano on your pizza and swallowing an oregano oil supplement. The Cleveland Clinic notes that oregano is safe to consume in food but is not recommended as a supplement or tea during pregnancy or nursing. The reason comes down to concentration: a pinch of dried oregano leaves in a recipe delivers trace amounts of the plant’s active compounds, while a single oregano oil capsule can contain the equivalent of several tablespoons of the dried herb.
Oregano essential oil, the kind sold for aromatherapy or topical use, is even more concentrated than the supplement form and should never be ingested. If you’ve been using oregano as a normal cooking spice, there’s no reason for alarm. The risk is specific to the concentrated oil products marketed as supplements.
How the Active Compounds Affect Your Body
Oregano oil’s two main active compounds can affect the body in ways that matter during pregnancy. One concern is bleeding risk. These compounds can slow blood clotting, which is why oregano oil supplements should be avoided before or after surgery and by anyone on blood thinners. During pregnancy, when your body is already managing significant changes in blood volume and clotting, this effect adds unnecessary risk.
Oregano oil can also interfere with how your body absorbs certain minerals, including iron, copper, and zinc. Iron deficiency is already common during pregnancy, and anything that blocks iron absorption works against you during a time when your iron needs nearly double.
There’s also a potential interaction with blood sugar regulation. If you have gestational diabetes or are taking medication to manage blood sugar, oregano oil could complicate that balance.
What About Topical Use?
The available research on oregano oil’s reproductive toxicity focused on oral consumption, and there’s very little data specifically addressing topical application during pregnancy. Because compounds applied to the skin can be absorbed into the bloodstream, and because there’s no established safe threshold for pregnant women, the general recommendation from researchers is to avoid or restrict the use of potentially harmful essential oil compounds during pregnancy. If you’ve been using diluted oregano oil on your skin for something like nail fungus or a minor skin issue, it’s worth switching to a pregnancy-safe alternative until after delivery.
Safer Alternatives for Immune Support
Many people reach for oregano oil when they feel a cold coming on or want to support their immune system. During pregnancy, a few options have stronger safety profiles.
- Ginger: One of the most thoroughly studied herbs in pregnancy. Doses under 1,000 mg per day have been shown to be safe for both mother and baby, and ginger is effective enough against nausea that it performs comparably to vitamin B6 in studies of severe morning sickness.
- Garlic: A large study of pregnant Norwegian women found that garlic intake was associated with a lower risk of spontaneous preterm delivery, possibly because of its antimicrobial properties. It reduced the risk of both early and late preterm birth.
- Echinacea: Research in Norwegian women found no link between echinacea use and birth defects or adverse effects. Oral consumption during the first trimester did not increase the risk of major malformations at recommended doses.
- Cranberry: Often used for urinary tract support, cranberry showed no increased risk of congenital malformations in a large cohort study. However, the evidence for its effectiveness against urinary tract infections is considered weak.
Even with these better-studied options, it’s worth mentioning any supplement you’re taking to your prenatal care provider. Herbal products can interact with medications and affect nutrient absorption in ways that aren’t always obvious, and your provider can help you weigh the benefits against the risks for your specific situation.