Licorice (Glycyrrhiza glabra
) contains glycyrrhizin (or glycyrrhizic acid), which has a long history of use in ethnoveterinary medicine.
Licorice has been used since 500 BC for the treatment of peptic ulcers, asthma, pharyngitis, malaria, abdominal pain, and infections.
: G. glabra
possesses some antiviral activity in vitro
toward a number of viruses---including Newcastle disease virus (NDV)
in chickens and Duck Hepatitis Virus (DHV) in ducks. In a study conducted on 40 day-old white Pekin domestic ducklings, treatment with glycyrrhizin alone or with DHV vaccine demonstrated to be an effective immune system booster and had an antiviral effect against DHV.