Over 200 types of headache exist, and the causes range from being harmless to life-threatening. The description of the headache, together with findings on neurological examination, determines the need for any further investigations and the most appropriate treatment. The most common types of headache are the "primary headache disorders" such as tension-type headache and migraine. They have typical features; migraine, for example, tends to be pulsating in character, affecting one side of the head. It is also associated with nausea, disabling in severity, and usually lasts between three hours and three days. Rarer primary headache disorders are trigeminal neuralgia (a shooting face pain), cluster headache (severe pains that occur together in bouts), and hemicrania continua (a continuous headache on one side of the head).