Marrubium vulgare White horehound contains the diterpene ‘murrubin’ which is a potent expectorant. Therefore it is often used as a remedy to help with coughs and has been used in many commercial cough mixtures. It is a bitter herb and has been used to help with stomach and digestive problems. It has also been used for pneumonia, asthma, bronchitis, ear problems, diarrhoea, to stimulate perspiration, and liver problems. Externally, it has been used to help with wounds and skin problems. White horehound has also been used for worming, but the Black Horehound is preferred for this. It is contraindicated (not to be used) during pregnancy or if ulcers are suspected.