Headache in general represents a major public health problem with a magnitude that has not been fully acknowledged until recently. While the percentage of the global adult population with migraine is approximately 10%, other forms of unilateral headaches such as cluster headache, paroxysmal hemicrania, hemicrania continua and short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT) syndrome are very rare. These headaches cause disability, suffering and loss of quality of life that easily compares to that of other chronic disorders. Continuous scientific research works towards a better understanding of these disorders and has accomplished a greater insight into the underlying pathophysiological mechanisms. This has led to improved treatment strategies in primary patient care that may prevent prolonged suffering of affected patients in the future.