Headaches are one of the most common medical complaints; most people experience them at some point in their life. They can affect anyone regardless of age, race, and gender. The World Health Organization (WHO) reports that almost half of all adults worldwide will experience a headache in any given year.
A headache can be a sign of stress or emotional distress, or it can result from a medical disorder, such as migraine or high blood pressure, anxiety, or depression. It can lead to other problems. People with chronic migraine headaches, for example, may find it hard to attend work or school regularly.
A headache can occur in any part of the head, on both sides of the head, or in just one location.
There are different ways to define headaches. The International Headache Society (IHS) categorize headaches as primary, when they are not caused by another condition, or secondary, when there is a further underlying cause.