The herb hyssop ( Hyssop officinalis) has a long history of use in both religion and medicine. The biblical phrase “purge me with Hyssop, and I shall be clean” echoes the ancient Greek use of this herb for cleansing sacred sites. Various preparations of hyssop have been used medicinally for respiratory problems, including cough, chest congestion, sore throat, and bronchitis. Hyssop has also been used to treat a variety of digestive problems, including stomach pain and intestinal gas. The fragrant essential oil of hyssop is an ingredient in the liqueur Chartreuse.

The essential oil of hyssop is still recommended by herbalists today for treatment of respiratory and digestive problems such as the common cold, asthma, acute bronchitis and cough, stomach upset, and intestinal gas. Hyssop tea is recommended as a gargle for sore throat. However, there is no meaningful evidence that it is effective for any of these purposes.

Very preliminary evidence, too weak to rely upon at all, hints that extracts of hyssop might have anti-HIV activity.1,2Other preliminary evidence weakly suggests that constituents in hyssop might reduce absorption of carbohydrates from the digestive tract.3,4 This has led to statements that hyssop is helpful for treating diabetes and aiding weight loss, but in reality the current evidence is far too weak to draw any such conclusion.