This is a very severe (“first or worst”) headache of an abrupt onset, reaching maximum intensity in less than 1 minute and lasting for 5 or more minutes. It can be a benign headache syndrome, but can also be associated with spinal fluid leak, vascular disorders, brain tumors, other structural abnormalities, aneurysm, tearing of an artery (dissection), other vascular abnormalities, or other “secondary causes”. Therefore, an evaluation with brain scans (brain and carotid CTA, or brain MRI and brain and carotid artery MRA) to exclude these potential treatable causes is necessary. It cannot be diagnosed until examination, further history, a recurrent pattern, and evaluations to exclude other causes of the headache have been performed with a physician. This headache requires emergent evaluation at the nearest emergency department for testing and evaluation, especially the first time that it occurs. One of the main diagnoses that needs to be evaluated for is a blood vessel related headache such as subarachnoid hemorrhage from aneurysm rupture (brain bleed).