I take propranolol, it's a blood pressure med that has proven itself to help with anxiety. It works for me by taking it twice a day everyday to bring my anxiety down. If your looking for a PRN then you want a different class of meds, benzodiazepines. They tend to be addictive on a daily bases. I don't remember enough about which ones are long term and those with a short half life. Someone here could probably tell you. There is also burspar (sp?) for me that one increased my anxiety but I hear I has helped some people. Good luck.

These may have different names in your country and you may have access to other more herbal remedies than they have in the USA.