Oregano is a common herb that is known for its amazing medicinal qualities within the mint family. The plant compounds give antiviral properties which include carvacrol.
In a test-tube study, oregano oil and isolated carvacrol both reduced murine norovirus (MNV) activity within 15 minutes of exposure (1Trusted Source).
MNV is highly contagious, and is the main cause of human stomach flu. It is very similar to human norovirus and used in scientific studies, since human norovirus in laboratory settings is notoriously difficult to develop.
Oregano oil and carvacrol also display antiviral activity against herpes simplex virus type-1 (HSV-1); rotavirus, a common cause of diarrhea in infants and children; and respiratory syncytial virus (RSV) that causes respiratory infections