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Plant Part Used

Leaf oil/ leaf extract

Active Constituents

Volatile oils (phenols including thymol and carvacrol, also terpenes including alpha and beta pinene, alpha terpinene); tocopherols; caffeic acid derivatives (mainly rosmarinic acid); flavonoids (includes naringin, apigenin, luteolin, quercetin).(1),(13)

[span class=alert]This section is a list of chemical entities identified in this dietary supplement to possess pharmacological activity. This list does not imply that other, yet unidentified, constituents do not influence the pharmacological activity of this dietary supplement nor does it imply that any one constituent possesses greater influence on the overall pharmacological effect of this dietary supplement.[/span]


Oregano has been used as a cooking spice and also as a medicinal agent for centuries. Oregano volatile oil has been used traditionally in various cultures for respiratory disorders such as coughs, bronchial catarrh, and as an expectorant; also for dyspepsia, rheumatoid arthritis, and urinary tract disorders.(1) Oregano oil is commonly used today as an antifungal and antibacterial agent for various conditions and applications.(2)

Turkey is the largest producer of oregano herb and oil to world markets.(14)

Interactions and Depletions


Dosage Info

Dosage Range

Standardized Leaf extract: 250-500mg, 3 times a day.

Concentrated oil extract: 5-10 drops in beverage, 3 times a day.

Tea: Use 5-10gm (1-2 teaspoonfuls) dried herb in 240ml (1 cup) hot water. Steep 5-10 minutes, strain and drink 2-4 times a day.(3)

Most Common Dosage

Standardized Leaf extract: 250mg, 3 times a day.

Concentrated oil extract: 5-10 drops in beverage, 3 times a day.

Tea: Use 5-10gm (1-2 teaspoonfuls) dried herb in 240ml (1 cup) hot water. Steep 5-10 minutes, strain and drink 2 times a day.(3)


[span class=doc]Standardization represents the complete body of information and controls that serve to enhance the batch to batch consistency of a botanical product, including but not limited to the presence of a marker compound at a defined level or within a defined range.[/span]

The most current available medical and scientific literature indicates that oregano leaf should be standardized to 5% thymol, and oregano oil should contain 75-85% carvacrol.


Frequently Reported Uses

  • Antioxidant
  • Antibacterial
  • Antifungal
  • Antiparasitic

Other Reported Uses

  • Anti-Inflammatory

Toxicities & Precautions


Oregano is reported safe in recommended dosages.


Allergies to oregano may develop or exist in sensitive individuals.(2)


As stated above, an application for oregano extract is its reported antibacterial and antifungal activity.(4) Oregano has also been reported to be an effective agent in vitro against Aspergillus spp.(5) Oil of oregano was orally administered to 14 adult patients whose stools tested positive for enteric parasites, Blastocystis hominis, Entamoeba hartmanni, and Endolimax nana. After six weeks of supplementation with 600mg of emulsified oil of oregano daily, there was complete disappearance of Entamoeba hartmanni (four cases), Endolimax nana (one case), and Blastocystis hominis in eight cases. Also, Blastocystis hominis scores declined in three additional cases. Gastrointestinal symptoms improved in seven of the eleven patients who had tested positive for Blastocystis hominis.(6) Laboratory studies also report activity of oregano oil against Staph. aureus and enterotoxin production.(15) The constituents thymol and carvacrol have reported antibacterial properties.(7) Oregano essential oil has been reported beneficial as extending shelf life of various foods, including chicken and fish.(16),(17)

Binding to intracellular progesterone receptors has been reported in vivo with the use of oregano extract.(8) Oregano also has reported antioxidant activity.(9),(18) Constituents in oregano that have reported antioxidant activity include flavonoids (rosmarinic acid) and the tocopherols.(10) The constituent rosmarinic acid (also found in other herbs such as Holy basil and rosemary) has been reported in vitro to have cyclooxygenase 2 (COX-2) inhibiting properties comparable to ibuprofen, naproxen, and aspirin at 10-, 100-, and 1000-microM concentrations, respectively.(11)

Oregano leaf extract has been reported in laboratory studies to have anticancer activity against various human cancer cell lines, with effects on redox balance, cell proliferation, and cell death.(19),(20)

Oregano does contain naringin and naringenin, chemical constituents contained in grapefruit juice, which has been reported to cause alterations in the metabolism of some drugs.(12) Use with caution in individuals on medications metabolized by the CYP3A4 pathway.


  1. Leung A, et al. Encylopedia of Common Natural Ingredients Used in Foods, Drugs, and Cosmetics. New York: Wiley-Interscience Publication; 1996:398-400.
  2. View Abstract: Dorman HJ, et al. Antimicrobial agents from plants: antibacterial activity of plant volatile oils. J Appl Microbiol. Feb2000;88(2):308-16.
  3. PDR for Herbal Medicines, 2nd edition. Montvale, NJ: Medical Economics Company; 2000:560.
  4. View Abstract: Benito M, et al. Labiatae allergy: systemic reactions due to ingestion of oregano and thyme. Ann Allergy Asthma Immunol. May1996;76(5):416-8.
  5. View Abstract: Basilico MZ, et al. Inhibitory effects of some spice essential oils on Aspergillus ochraceus NRRL 3174 growth and ochratoxin A production. Lett Appl Microbiol. Oct1999;29(4):238-41.
  6. View Abstract: Force M, et al. Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytother Res. May2000;14(3):213-4.
  7. View Abstract: Didry N, et al. Antibacterial activity of thymol, carvacrol and cinnamaldehyde alone or in combination. Pharmazie. Apr1993;48(4):301-4.
  8. View Abstract: Zava DT, et al. Estrogen and progestin bioactivity of foods, herbs, and spices. Proc Soc Exp Biol Med. Mar1998;217(3):369-78.
  9. View Abstract: Lamaison JL, et al. Medicinal Lamiaceae with antioxidant properties, a potential source of rosmarinic acid. Pharm Acta Helv. 1991;66(7):185-8.
  10. View Abstract: Lagouri V, et al. Nutrient antioxidants in oregano. Int J Food Sci Nutr. Nov1996;47(6):493-7.
  11. View Abstract: Kelm MA, Nair MG, Strasburg GM. Antioxidant and Cyclooxygenase Inhibitory Phenolic Compounds from Ocimum sanctum Linn. Phytomedicine. Mar2000;7(1):7-13.
  12. View Abstract: Bailey DG, et al. Grapefruit juice-drug interactions. Br J Clin Pharmacol. Aug1998;46(2):101-110.
  13. Hawas UW, El-Desoky SK, Kawashty SA, Sharaf M. Two new flavonoids from Origanum vulgare. Nat Prod Res. 2008;22(17):1540-1543.
  14. Baser KH. Biological and pharmacological activities of carvacrol and carvacrol bearing essential oils. Curr Pharm Des. 2008;14(29):3106-3119. Review.
  15. de Souza EL, de Barros JC, de Oliveira CE, da Conceição ML. Influence of Origanum vulgare L. essential oil on enterotoxin production, membrane permeability and surface characteristics of Staphylococcus aureus. Int J Food Microbiol. 28 Feb 2010;137(2-3):308-311. Epub 2009 Dec4.
  16. Chouliara E, Karatapanis A, Savvaidis IN, Kontominas MG. Combined effect of oregano essential oil and modified atmosphere packaging on shelf-life extension of fresh chicken breast meat, stored at 4 degrees C. Food Microbiol. Sep 2007;24(6):607-617. Epub 2007 Jan 12.
  17. Frangos L, Pyrgotou N, Giatrakou V, Ntzimani A, Savvaidis IN. Combined effects of salting, oregano oil and vacuum-packaging on the shelf-life of refrigerated trout fillets. Food Microbiol. Feb 2010;27(1):115-121. Epub 2009 Sep 15.
  18. El-Ashmawy IM, Saleh A, Salama OM. Effects of marjoram volatile oil and grape seed extract on ethanol toxicity in male rats. Basic Clin Pharmacol Toxicol. Nov 2007;101(5):320-327.
  19. Savini I, Arnone R, Catani MV, Avigliano L. Origanum vulgare induces apoptosis in human colon cancer caco2 cells. Nutr Cancer. 2009;61(3):381-389.
  20. Srihari T, Sengottuvelan M, Nalini N. Dose-dependent effect of oregano (Origanum vulgare L.) on lipid peroxidation and antioxidant status in 1,2-dimethylhydrazine-induced rat colon carcinogenesis. J Pharm Pharmacol. Jun 2008;60(6):787-794.

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