Related Terms

• Carvacrol, Dostenkraut (German), eugenol, Greek oregano, Italian oregano (Origanum x majoricum), kekik (Turkish), Lamiaceae, Mediterranean oregano, mountain mint, O. minutiflorum Hausskn., O. vulgare spp. vulgare, oil of oregano, oregamax, oregano oil, oregano spirits, Oregpig®, Origani vulgaris herba, origano, origanum, Origanum acutidens (Hand.-Mazz.) Ietswaart, Origanum compactum, Origanum compactum, Origanum cordifolium, Origanum creticum, Origanum dayi, Origanum dubium, Origanum floribundum, Origanum heracleoticum, Origanum libanoticum, Origanum micranthum, Origanum microphyllum, Origanum minutiflorum, Origanum officinalis, Origanum onites, Origanum scabrum, Origanum syriacum, Origanum tyttanthum, Origanum vulgare, Origanum x applii, Origanum x intercedens, Origanum x majoricum, P73 oreganol, Spanish oregano, Syrian oregano, Syrian oreganum, thymol, Toka oregano, Turkish oregano, Turkish Origanum acutidens, wild marjoram, wintersweet, zaatar.

Background

• Oregano (Origanum vulgare) leaves, stems, and flowers are used medicinally. Oregano has been recognized for its aromatic properties since ancient times. Today, oregano is commonly used as a food flavoring and preservative.

• Traditionally, oregano has been used to treat respiratory, gastrointestinal, and menstrual problems. Modern herbalists recommend application of oregano oil on the skin for the treatment of infection.

• According to early research, oregano may have antiparasitic, antifungal, antioxidant, antibacterial, and insect repellent properties. Oregano may also reduce the risk of heart disease and is occasionally used in dentistry. There is limited scientific evidence to support any of these suggested uses for oregano.

Scientific Evidence

Tradition/Theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

• Abortifacient, acne, aging, allergies, altitude sickness, Alzheimer's disease, anthrax, antibacterial, antifungal, antimutagenic, antioxidant, antiparasitic, antiseptic, antispasmodic, antithrombotic, antiviral, arthritis, asthma, athlete's foot (topically), bad breath, bloating, bronchitis, bursitis, cancer, candidal infection, canker sores (topically), carminative, colds, colitis, cough, croup, dandruff, dental conditions (abscess, infection), diabetes, diabetic complications, diaphoretic, diarrhea, digestion, diuresis (increased urination), earache, expectorant, flavoring, flu, food poisoning, food preservative, gastrointestinal disorders, gum disease (topically), headaches, heart conditions, Helicobacter pylori infection, herpes, high blood pressure, high blood sugar/glucose intolerance, high cholesterol, hormonal effects, immune system function, infectious diarrhea, inflammation, insect and spider bites, insect repellent, intestinal disorders, joint pain, lice, liver protection, longevity, menstrual stimulant (orally), methicillin-resistant Staphylococcus aureus (MRSA), muscle pain, nausea, obesity, pain, painful menstruation, preservative, psoriasis, respiratory disorders, ringworm (topically), rosacea, seborrhea, shingles (herpes zoster), sinus infection, sore throat, stomach ache, swelling, tick repellant, tonic (mild), toothache, ulcers, urinary tract infections, varicose veins, warts.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

• There is no proven effective dose for oregano. Oregano has been taken in the following forms by mouth: capsules, oregano oil, leaf extract, and tea. For heart disease risk reduction, 25 milliliters of an Origanum onites product after each meal has been used for three months. For reduction of bleeding after tooth extraction, 30 milliliters of an herbal infusion of oregano (1:10 concentration) has been used six times daily for ten days. For intestinal parasites, 200 milligrams of emulsified Origanum vulgare oil has been used three times daily with meals for six weeks.

• Oregano oil has also been applied on the skin, used in shampoos and mouthwash, and added to the bath.

Children (under 18 years old)

• There is no proven effective dose for oregano in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

• Avoid in individuals with a known allergy or hypersensitivity to oregano, its constituents, and other members of the Lamiaceae family. Possible cross-sensitivity exists with other herbs from the Lamiaceae family including hyssop (Hyssopus officinalis), basil (Ocimum basilicum), marjoram (Origanum majorana), mint (Mentha piperita), sage (Salvia officinalis), and lavender (Lavendula officinalis).

• Itching and swelling of the lips and tongue, difficulty speaking and breathing, and face swelling have been reported following the ingestion of pizza containing oregano. Other potential allergic reactions include contact dermatitis.

Side Effects and Warnings

• Oregano may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare provider. Medication adjustments may be necessary.

• Oregano may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or those taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

• Oregano may cause low blood pressure. Caution is advised in patients with low blood pressure and in those taking drugs, herbs, or supplements that lower blood pressure.

• Caution is advised in patients using mineral (zinc, iron, copper) supplements, central nervous system depressants, and agents that affect the immune system.

Pregnancy and Breastfeeding

• Oregano is not recommended during pregnancy at doses above those normally found in food, due to a lack of available scientific evidence and historical use to induce abortions. An over-the-counter product (Carachipita®) containing oregano, pennyroyal (Mentha pulegium), yerba de la perdiz (Magiricarpus pinnaus), and guaycuru (Statice brasiliensis) may induce abortion. Although study in humans is lacking, oregano oil and its constituents have been reported to increase death of early embryo cells.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

• Oregano may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

• Oregano may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, antiplatelet drugs such as clopidogrel (Plavix®), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

• Oregano may cause low blood pressure. Caution is advised in patients taking drugs that lower blood pressure.

• Because oregano contains estrogen-like chemicals, the effects of other agents believed to have estrogen-like properties may be altered.

• Oregano may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, and alcohol. Caution is advised while driving or operating machinery.

• Oregano may also interact with Alzheimer's agents, anthelminthics (for intestinal worms), anti-anxiety agents, antibiotics, anti-cancer agents, antidiarrheals, antifungals, anti-inflammatory agents, antiprotozoals, antivirals, cholesterol-lowering agents, drugs that affect the immune system, furosemide, and hormonal agents.

Interactions with Herbs and Dietary Supplements

• Oregano may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

• Oregano may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

• Oregano may cause low blood pressure. Caution is advised in patients taking herbs or supplements that lower blood pressure.

• Because oregano contains estrogen-like chemicals, the effects of other herbs or supplements believed to have estrogen-like properties may be altered.

• Oregano may increase the amount of drowsiness caused by some herbs or supplements.

• Oregano may also interact with Alzheimer's agents, anthelminthics (for intestinal worms), anti-anxiety herbs and supplements, antibacterials, anti-cancer herbs and supplements, antidiarrheals, antifungals, anti-inflammatory agents, antioxidants, antiprotozoals, antivirals, basil, capsicum oleoresin, carvacrol, cholesterol-lowering herbs or supplements, cinnamaldehyde, copper, cranberry, fenugreek, formic acid, garlic, green tea, herbs or supplements that affect the immune system, hormonal herbs or supplements, iron, lactic acid, methyl gallate, Mucuna pruriens, prebiotics, sunflower oil, sweet marjoram, thyme, vitamin E, zinc.

Author Information

• This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Bagamboula CF, Uyttendaele M, Debevere J. Antimicrobial effect of spices and herbs on Shigella sonnei and Shigella flexneri. J Food Prot 2003;66(4):668-673. View Abstract

2. Burt SA, Reinders RD. Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7. Lett Appl Microbiol 2003;36(3):162-167. View Abstract

3. Chami F, Chami N, Bennis S, et al. Oregano and clove essential oils induce surface alteration of Saccharomyces cerevisiae. Phytother Res 2005;19(5):405-408. View Abstract

4. Chorianopoulos N, Kalpoutzakis E, Aligiannis N, et al. Essential oils of Satureja, Origanum, and Thymus species: chemical composition and antibacterial activities against foodborne pathogens. J Agric Food Chem 2004;52(26):8261-8267. View Abstract

5. Ciganda C, Laborde A. Herbal infusions used for induced abortion. J Toxicol Clin Toxicol 2003;41(3):235-239. View Abstract

6. Dorman HJ, Deans SG. Antimicrobial agents from plants: antibacterial activity of plant volatile oils. J Appl Microbiol 2000;88(2):308-316. View Abstract

7. Exarchou V, Nenadis N, Tsimidou M, et al. Antioxidant activities and phenolic composition of extracts from Greek oregano, Greek sage, and summer savory. J Agric Food Chem 2002;50(19):5294-5299. View Abstract

8. Force M, Sparks WS, Ronzio RA. Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytother Res 2000;14(3):213-214. View Abstract

9. Giordani R, Regli P, Kaloustian J, et al. Antifungal effect of various essential oils against Candida albicans. Potentiation of antifungal action of amphotericin B by essential oil from Thymus vulgaris. Phytother Res 2004;18(12):990-995. View Abstract

10. Goun E, Cunningham G, Solodnikov S, et al. Antithrombin activity of some constituents from Origanum vulgare. Fitoterapia 2002;73(7-8):692-694. View Abstract

11. Klement AA, Fedorova ZD, Volkova SD, et al. [Use of a herbal infusion of Origanum in hemophilia patients during tooth extraction]. Probl.Gematol.Pereliv.Krovi 1978;(7):25-28. View Abstract

12. Lambert RJ, Skandamis PN, Coote PJ, et al. A study of the minimum inhibitory concentration and mode of action of oregano essential oil, thymol and carvacrol. J Appl Microbiol 2001;91(3):453-462. View Abstract

13. Marino M, Bersani C, Comi G. Impedance measurements to study the antimicrobial activity of essential oils from Lamiaceae and Compositae. Int J Food Microbiol 2001;67(3):187-195. View Abstract

14. Nevas M, Korhonen AR, Lindstrom M, et al. Antibacterial efficiency of Finnish spice essential oils against pathogenic and spoilage bacteria. J Food Prot 2004;67(1):199-202. View Abstract

15. Ozdemir B, Ekbul A, Topal NB, et al. Effects of Origanum onites on endothelial function and serum biochemical markers in hyperlipidaemic patients. J Int Med Res 2008;36(6):1326-1334. View Abstract