At what point should i go to an er for migraine headaches?

Life Threatening: If you feel your life is in danger, that is when you go to the er. Otherwise, go see your regular physician. If you don't have a regular physician, find one who treats migraines and go there. You will only waste your time going to the er, where the staff is specifically trained to handle short-term emergencies, not long-term problems like migraines.

Avoid ER period: The very worst place to go with a migraine, as very expensive, you will have to wait a long time, it is bright, noisy, irritating, and will make your headache feel far worst. You will be examined repetitively, placed through many tests, and likely give a narcotic injection which will wear off within 3-4 hrs, where-upon your headache will rebound. Instead, be pro-active, and see your regular doc.