The Bible mentions hyssop many times (Leviticus 14:1–7). David says hyssop in Psalm 51:7: “Cleanse me with hyssop, and I will be clean; wash me, and will be whiter than snow.”
Tea made from the leaves is traditionally used to treat flatulence and stomachache. In the sixteenth and seventeenth centuries, a hot infusion with vapors was used to treat ear ailments.
Hyssop is believed to irritate the mucous membranes. Thus herbalists recommend its use only when the infection of the respiratory tract has subsided. Pregnant women should not use the plant; when ingested in large quantities, it can induce miscarriage.
The antimicrobial, antifungal, and antioxidant properties have been tested and validated in animal trials (Kizil et al., 2010). The U.S. FDA declared hyssop “Generally Recognized as Safe,” although convulsions in rats have been observed during experimental trials.
In my research on herbs used in medicine, I did not come across any human clinical trials that would validate any herbs’ traditional medicinal properties.
Additional reading:
Holy Herbs: Modern Connections to Ancient Plants