Can Oil of Oregano Be Used as a Mosquito Repellent?

Oregano (‌Origanum vulgare‌), which is hardy in U.S. Department of Agriculture plant hardiness zones 4 through 8, is a tasty herb, and it's recommended as a folk remedy for illnesses such as diabetes and spasms, although little evidence exists to support these recommendations. Some gardeners use it as a plant to repel mosquitoes, and others claim the essential oil is a mosquito repellent. Scientific evidence to support this claim is scarce, but oregano does contain two chemicals with known repellent properties, and because oregano is generally recognized as safe, it doesn't hurt to experiment for yourself.

Studies demonstrated the effectiveness of ‌thymol‌ -- one of the main components of garden thyme (‌Thymus vulgaris‌), hardy in zones 5 to 9 -- in controlling houseflies. Another compound found in thyme -- ‌carvacrol‌ -- is noted for insect control, and oil of oregano contains both of these compounds in concentrations of 38.8 and 32.9 percent respectively.

Oil of thyme is a 100 percent-effective repellent against ‌anopheles quadrimaculatus‌ -- a species of mosquito that carries malaria -- but only as long as 30 minutes when applied to clothing. Because it contains the same repellent compounds, oil of oregano may well be equally effective, although few sources support this.

Even though oregano is generally recognized as safe, the essential oil can cause allergic contact dermatitis when applied topically to sensitive individuals. There are several ways around this.

• Create a dilute solution by adding a few drops of oregano oil to 8 ounces of water, put the solution in a spray bottle and spray it on your skin. Diluting the solution, however, will also lessen any potential effectiveness of the oil.
  
• Mix a few drops of the essential oil in several ounces of a carrier oil, such as coconut oil, olive oil or sweet almond oil, and apply it to your skin with a cotton swab.
  
• Make a more concentrated spray solution with water and spray your clothes.
  

In all cases, you'll have to reapply the repellent every 30 minutes to potentially keep mosquitoes away. If you feel any skin irritation, discontinue use and look for an alternative repellant method.