Typically the headache is unilateral and pulsating in nature, lasting from 2 to 72 hours.[1] Headache is the second most common reason for a visit to a doctor.There are approximately 45 million Americans complaining of headaches each year. That works out to about one in every six people or 16.54% of the population.[2]Migraine headaches often begin in childhood, adolescence or early adulthood.[3]