For sore throats problems as a gargle.
The plant does contain anti-viral and antiseptic properties, and is safe for use in moderation.
Externally, Hyssop leaves can be made into an Ointment or pounded into a poultice - add tea or water, and maybe some oatmeal to reach desired consistency. This can be used for treating, cuts, scrapes, bruises, cold sores, herpes sores, and to heal scars.
To make a Hyssop compress, use one ounce of herb to 1 pint of boiling water. Let it steep for up to 30 minutes, covered, then cool, soak a clean cloth in it and apply.