When should you go to the emergency room with high blood pressure?

Symptoms: When you have symptoms of hypertensive crisis: angina, heart failure or encephalopathy.

Depends: Regardless of number, high BP should be treated. Acute rise in BP associated with symptoms should be treated promptly. Most would agree that systolic BP > 200 and diastolic BP > 120 should be treated urgently. Acute organ damage e.g. Cardiac or neurologic is treated as emergency.