"Oregano essential oil should never be used undiluted. Always dilute it in a suitable carrier oil, such as olive oil, almond oil, or v-6 mixing oil. As with any product used for medicinal purposes, it is important to read and follow the label instructions and warnings.
A skin patch test should be conducted prior to using oregano essential oil for the first time. To do this, place a small amount of diluted essential oil on the inside of your elbow and apply a bandage. Wait 24 hours to see if there is any negative reaction, such as redness or irritation, before proceeding with more extensive use.
Because essential oregano oil is concentrated, a little bit goes a long way. At first, it may be wise to start out cautiously by using only 1 drop of essential oregano oil to 3 parts olive oil and massage into the affected area once or twice a day.
To topically treat fungal infections on the skin and nails, Dr. Jennifer Brett, a naturopathic physician and chair of the botanical medicine department at the University of Bridgeport College of Naturopathic Medicine in Connecticut suggests the following: Dilute 1 teaspoon essential oregano oil in 2 teaspoons olive oil and apply with a cotton swab to the affected area up to three times a day.
To treat bacterial and fungal infections in other parts of the body, 1 drop of oil may be placed in an 8-ounce glass of water or juice once or twice a day. One drop may also be placed under the tongue twice a day, but it should be mixed with 1 teaspoon of honey, maple syrup, or olive oil.
For use in the bath, mix 1 to 3 drops of diluted oregano essential oil with body gel or shampoo and add it to the bath water. As an antiseptic, the diluted oil can be used in cloths to wipe down kitchen and bathroom countertops."