Horehound, people have used it for centuries as a cold remedy.

Horehound [Marrubium vulgare] is a natural cough suppressant. Horehound belongs to the mint family, a vigorous aromatic, but bitter plant that is easy to grow. Both the flowers and leaves have medicinal uses. Native people throughout North America have used it for centuries as a cold remedy. For easy cough relief, steep horehound for 15 minutes in water, strain and gargle frequently. Mix a little honey with the liquid to remove any bitterness. The liquid forms a soothing film over a mucous membrane, relieving minor pain and inflammation. Horehound is also used to flavour ale. Enjoy Australia's ABC Radio discussion including recipes for alcohol-free horehound beer.