Oregano oil has been found to be effective in destroying pathogenic bacteria, fungi and protozoal parasites, such as: Candida albicans, Aspergillus, Staphylococcus, Streptococcus, Campylobacter, Klebsiella, E. coli, Giardia, and Proteus and a variety of viral organisms.
Oregano oil is a potent anti-fungal and anti-microbial agent, exhibiting these effects in dilutions down to 1/50,000.
It has also been used in the treatment of periodontal disease, when a couple of drops are brushed on teeth and gums with or without toothpaste in the morning and evening. It may also be useful in treating halitosis, when it is the result of poor oral hygiene and growth of bacteria.