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. A headache can occur in any part of the head, on both sides of the head, or in just one location.
Headaches can radiate across the head from a central point or have a vise-like quality. They can be sharp, throbbing or dull, appear gradually or suddenly. They can last from less than an hour up to several days.
There are different ways to define headaches. The International Headache Society (IHS) categorizes headaches as primary, when they are not caused by another condition, or secondary, when there is a further underlying cause.