The vast majority of headaches are benign and self-limiting. Common causes are tension, migraine, eye strain, dehydration, low blood sugar, hypermastication and sinusitis. Much rarer are headaches due to life-threatening conditions such as meningitis, encephalitis, cerebral aneurysms, extremely high blood pressure, and brain tumors. When the headache occurs in conjunction with a head injury the cause is usually quite evident. A large percentage of headaches among women are caused by ever-fluctuating estrogen during menstrual years. This can occur prior to, or even during midcycle menstruation.
Treatment of an uncomplicated headache is usually symptomatic with over-the-counter painkillers such as aspirin, paracetamol (acetaminophen), or ibuprofen, although some specific forms of headaches (e.g., migraines) may demand other, more suitable treatment. It may be possible to relate the occurrence of a headache to other particular triggers (such as stress or particular foods), which can then be avoided.
Other kinds of vascular headaches include cluster headaches, which are very severe recurrent short lasting headaches, often located through or around either eye and often wake the sufferers up at the same time every night. Unlike migraines, these headaches are more common in men than in women.
Traction and inflammatory headaches are symptoms of other disorders, ranging from stroke to sinus infection. Specific types of headaches include:
A headache may also be a symptom of sinusitis.
Like other types of pain, headaches can serve as warning signals of more serious disorders. This is particularly true for headaches caused by inflammation, including those related to meningitis as well as those resulting from diseases of the sinuses, spine, neck, ears, and teeth.
Headache associated with specific symptoms may warrant urgent medical attention, particularly sudden, severe headache or sudden headache associated with a stiff neck; headaches associated with fever, convulsions or accompanied by confusion or loss of consciousness; headaches following a blow to the head, or associated with pain in the eye or ear; persistent headache in a person with no previous history of headaches; and recurring headache in children.
The most important step in diagnosing a headache is for the physician to take a careful history and to examine the patient. In the majority of cases the diagnosis will be a "primary headache" which means that the headache, whilst unpleasant is not an occurring as a manifestation of a more serious condition. The main types of primary headache are tension headache, migraine and the trigeminal autonomic cephalalgias of which cluster headache is an example. As it is often difficult for patients to recall the precise details regarding each headache, it is often useful for the sufferer to fill-out a "headache diary" detailing the characteristics of the headache. When the headache does not clearly fit into one of the recognized primary headache syndromes or when atypical symptoms or signs are present then further investigations are justified. Computed tomography (CT/CAT) scans of the brain or sinuses are commonly performed, or magnetic resonance imaging (MRI) in specific settings. Blood tests may help narrow down the differential diagnosis, but are rarely confirmatory of specific headache forms.
In recurrent unexplained headaches, healthcare professionals may recommend keeping a "headache diary" with entries on type of headache, associated symptoms, precipitating and aggravating factors. This may reveal specific patterns, such as an association with medication, menstruation or absenteeism or with certain foods. It was reported in March 2007 by two separate teams of researchers that stimulating the brain with implanted electrodes appears to help ease the pain of cluster headaches.
Petasites, magnesium, feverfew. riboflavin, CoQ10, and melatonin are "natural" supplements that have shown some efficacy for migraine prevention; a 2006 review tentatively ranked petasites and magnesium with the best evidence, and melatonin with by far the least. Adverse events included sore mouth and tongue (including ulcers) and abdominal pain for feverfew.
Spinal manipulation is associated with frequent, mild and temporary adverse effects, including new or worsening pain or stiffness in the affected region. They have been estimated to occur in 34% to 55% of patients, with 80% of them disappearing within 24 hours. Spinal manipulation, particularly on the upper spine, can also result in complications that can lead to permanent disability or death. The incidence of these complications is unknown, due to high levels of underreporting and to the difficulty of linking manipulation to adverse effects such as stroke, a particular concern. Weak to moderately strong evidence supports causation (as opposed to statistical association) between cervical manipulative therapy (whether chiropractic or not) and vertebrobasilar artery stroke.