Hyssop contains marrubiin, which is also found in horehound, and ursolic acid, which has anti-inflammatory activity. The essential oil of Hyssop is antispasmodic and bacteriostatic. Traditionally used to treat lung conditions such as bronchitis, coughs and colds.

Studies have also shown it inhibits HIV, whcih suggest it could enhance the immune system. 

Found in Potter’s Cough Remover and Potter's Catarrh Mixture