How many days dose it take for 10mg of propranolol to work fully for panic attacks?

Don't keep waiting: propranolol carries an indication for panic disorder at doses of 40mg once daily and higher. Dosing is balanced against its blood-pressure lowering effect which can be troublesome in some healthy patients. Effect should not take more than 4 hours from the time of dosing and is not cumulative over weeks or months like other anxiety medications such as SSRI class or SNRI class meds.