Hyssop is considered safe for most people in the amounts commonly found in foods and in medicinal amounts. However, do not use the oil product because it has caused seizures in some people.
Pregnancy and breast-feeding: It is unsafe to use hyssop during pregnancy because it might cause the uterus to contract or start menstruation. These effects could lead to a miscarriage.
It is not known whether hyssop is safe to use during breast-feeding. Stay on the safe side and avoid use.
Children: It is unsafe to give hyssop to children. Convulsions were reported in a child who took 2-3 drops of hyssop oil over several days.
Seizures: If you have a history of having seizures, donot use hyssop. It might trigger seizures or make them worse.