Oregano is also known as Wild Marjoram. It is a culinary and medicinal herb that grows upright and can reach heights of 32 inches. It has square stems, oval leaves, and produces pink flowers in clusters. It is native to Europe, growing in chalky soils. Oregano is now cultivated worldwide. 
Historically, Oregano use dates back thousands of years. It was used as a therapeutic agent in both Greek and Chinese cultures. In ancient Greece, oregano was thought of as a cure all; believed to help treat conditions from wounds on the skin to aching muscles and headache. It was often applied in a compress as well. The Chinese used Oregano to relieve fever, as well as to treat vomiting, diarrhea, liver inflammation, and itching skin. 
Current uses of Oregano include; gas and bloating (GI distress), cough, bronchitis, urinary tract ailments, painful menstruation, rheumatoid arthritis, and swollen lymph nodes. Oregano is also antimicrobial in nature, and can treat fungal skin and vaginal infections.
The primary constituents of Oregano are its volatile oils. The most well known of these oils include; thymol, carvacrol, and rosmarinic acid. Oregano also contains beneficial tannins, resins, sterols, and flavonoids. Thymol and carvacrol are known antimicrobials, effective against a wide spectrum of bacteria and fungus, including Candida.  Rosmarinic acid is believed to be a COX-2 inhibitor, which blocks the inflammatory pathways responsible for pain and swelling. It produces effects similar to the well known over-the-counter drugs Aleve and Ibuprofen. The flavonoid content of Oregano make it a useful antioxidant as well.
Uses ascribed to Oregano (wild marjoram):
- diaphoretic (causes sweating)
The aerial parts, or those above ground, are used medicinally. This includes the stems, leaves, and flowers. The essential oils derived from various parts of the plant can be used externally or internally, if diluted.
Oregano is considered a useful agent for the treatment of cough, bronchitis, and other upper respiratory infections that manifest with excessive mucous or phlegm production.  Oregano contains thymol and carvacrol, two particularly volatile oils, with known ability to break up mucous and promote expectoration.
- Oregano is also anti-microbial against many bacterium that can cause bronchitis and other upper respiratory conditions.  It also has the ability to decrease spasm in the bronchioles, which may be helpful for chronic bronchitis and asthma sufferers.
- Oregano is thought to be an effective treatment for infection of the GI tract. It is effective at killing several parasites known to affect the intestines.  Oregano also is anti-bacterial and may assist in cases of diarrhea due to food poisoning or gastroenteritis.
- Oregano has proven effective at killing Candida (Yeast).  Therefore, It can be employed to treat Candida infections in the GI tract, vagina, and on the skin.
- Oregano may be equally helpful for dyspepsia, or upset stomach. It is a carminative herb that is known to ease upset stomach. Oregano may promote the relief of gas and bloating by the same carminative action. 
- Used as a gargle, Oregano can be helpful for infections or inflammation located in the mouth.  Its antimicrobial action can assist in the elimination of infectious organisms; it is also a potent astringent because of its tannins.
- Oregano may be helpful for arthritis, including the rheumatoid variety. It is anti-inflammatory and analgesic in nature, and can be used topically in a cream and massaged over arthritic areas.
- Oregano may also be cancer preventative. It has shown modest anti-cancer activity against specific malignancies, including leukemia.  However, further studies are needed to determine the extent of Oregano’s anti-cancer action.
- Oregano is high in antioxidants and may be protective against the development of heart disease, including atherosclerosis. 
Oregano can be used safely with mild medical effects as a culinary herb. In small doses the effect may be minimal. Oregano can be taken internally as a tea, tincture, or in capsules which include parts of the leaf. Externally, the essential oil can be applied in diluted form in a cream or gel, or alone in smaller doses. This application is proposed to have certain aromatic benefit, producing a calmative or ‘warming’ sense.
- Tea - infusion of 1 teaspoon of dried herb per cup of water. Pour boiling water over herb and steep for 10-15 minutes. Cover to trap the volatile oils, which can be lost in the steam.
- Tincture - 3 - 6 ml per day of a 1:4 tincture. Taken in 4 ounces of water on an empty stomach.
- Capsules - 200 - 500 mg, three times a day of the leaf; standardized to 5% thymol.
- Oil - 5 - 10 drops three times a day. Not to be taken internally unless diluted.
Side effects due to ingestion of Oregano include mild stomach upset. There have been cases of allergic reaction to Oregano, therefore its consumption remains ill-advised if you are or have had an allergic reaction to oregano in the past. The essential oils found in the Oregano herb can be toxic if taken internally, resulting from the volatile oils contained.
Women who are pregnant should not take Oregano because it may stimulate the uterus to contract causing a miscarriage. Additionally, there is not sufficient evidence or knowledge about the effects the volatile oils may have on the developing fetus.
Oregano may inhibit the absorption of iron. If you are taking iron for medical reasons, it should be taken apart from Oregano, to avoid possible malabsorption. 
1. Chevallier A. Encyclopedia of Herbal Medicine, 2nd Ed.; 2000. Dorling Kindersley, New York: 242.
2. http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101840.shtml Oregano. February 2005.
3. Lamert RJ, Skandamis PN, Loote PJ, Nychas BJ. A study of the minimum inhibitory concentration and mode of action of Oregano essential oil, thymol, and carvacrol. J Appl Microbiol. 2001 Sep; 91(3): 453-462.
4. http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101840.shtml Oregano. February 2005.
5. Kohlert C et al. Systemic availability and pharmokinetics of thymol in humans. J Clin Pharmacol. 2002 Jul; 42(7): 731-737.
6. Force M, Spartes WS, Ronzio RA. Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytother Res. 2000 May; 14(3): 213-214.
7. Cham N et al. Study of anticandidal activity of carvacrol and eugenol in vitro and in vivo. Oral Microbiol Immunol. 2005 Apr; 20(2): 106-111.
8. Hoffmann D. The New Holistic Herbal, 4th Ed., 1992. Element Books, Boston Massachusetts: 214.
9. Hoffmann D. The New Holistic Herbal, 4th Ed., 1992. Element Books, Boston Massachusetts: 214.
10. Goun E, Cunningham G, Solodnikov S, Krasnykch O, Miles H. Antithrombin activity of some constituents from Origanum vulgare. Fitoterapia. 2002 Dec; 73(7-8): 692-694.
11. Dragland S, Senoo H, Wake K, Holte K, Blomhoff R. Several culinary and medicinal herbs are important sources of dietary antioxidants. J Nutr. 2003 May; 133(5): 1286-1290.
12. Brune M, Rossander L, Hallberg L. Iron absorption and phenolic compounds: importance of different phenolic structures. Eur J Clin Nutr. 1989 Aug; 43(8): 547-557.