A member of the mint family and a close relative of marjoram, the herb oregano contains thymol and carvacrol, two potent antimicrobials capable of fighting killer bacteria such as E. coli. Researchers have also cited oregano, which is rich in flavonoids and polyphenols, for its potential in Type 2 diabetes management. One way to reap the benefits is to brew oregano as a tea, using 1 to 2 teaspoons of the herb per cup of hot water. However, while it shows some healing properties, oregano may have side effects, too, so check with your doctor before self-treating with this or any herb.
The U.S. Food and Drug Administration lists oregano as generally recognized as safe, and herbs deemed GRAS are presumably safe in tea as well. However, there has been a lack of research on the safety of herbal teas like oregano during pregnancy. The website Pregnancy and Children says pregnant women should use oregano in moderation only, for flavoring, because in larger amounts it can cause uterine contractions. When brewed in tea, herbs are more concentrated, points out the website Baby Center. In some people, oregano can cause rashes and other severe allergic reactions, states Drugs.com.