"Headache has been underestimated, under-recognized and under-treated throughout the world." - World Health Organization 
What are headaches?
The term 'headache disorder' is used to describe a range of disorders of the nervous system that vary in cause, symptoms and severity. Someone suffering from a headache disorder typically (but not always) experiences pain in the head, face or neck.
Headache disorders can be categorised into two groups:
Primary headache disorders - where the headache is itself a condition (e.g. migraine, tension-type headaches, cluster headaches)
Secondary headache disorders - where the headache is a symptom that is triggered by another disorder (e.g. overuse of medication, concussion, disruption of blood vessels, high blood pressure, infection, stress).
How common are headaches?
According to the WHO :
50% of adults are estimated to have suffered from headache disorder within the past year
Of these sufferers, at least 30% have reported experiencing migraine
Between 1.7% and 4% of adults suffer from headaches for 15 or more days each month.
"Headache disorders are a worldwide problem, affecting people of all ages, races, income levels and geographical areas." - World Health Organization 
What are the symptoms and causes of headache disorders?
Tension-type headaches are the most common primary headache disorder and are typically described as involving a dull, squeezing pain or tightness on both sides of the head.
In most cases, these headaches occur infrequently and cause mild to moderate pain from around 20 minutes to 2 hours. However, many people experience severe pain several days per week. People may also experience aching in the neck and shoulders.
They typically begin during the teenage years and are more common in women, affecting three women to every two men.
Tension-type headaches are generally classified as:
episodic - occurring fewer than 15 days per month
chronic - occurring at least 15 days per month
Possible causes of tension-type headaches include:
musculo-skeleto problems in the neck, jaw or shoulders
Migraine is a primary headache disorder that is more common in women, affecting two women to every man.
People suffering from migraine typically experience headaches of moderate to severe intensity that pulsate on one side and can last anywhere between a few hours and 2-3 days. The frequency of such attacks is usually between once a week and once a year. The condition is often accompanied with feelings of nausea.
Causes of migraine are varied and very individual. As such, consider keeping a diary in order to try to individual what triggers your migraine. Triggers may be related to:
Cluster headaches are primary headache disorders usually described as involving brief but extremely intense pain on one side of the head, often around the eye. They tend to come in groups (clusters) of headaches at a similar time each day and can last for between 6 and 12 weeks . Other symptoms may include red or watery eye, a runny nose or a sagging eyelid.
These headaches are relatively uncommon, affecting less than one in a thousand people and typically developed after the age of 20. They are more common in men than women by a factor of six to one.
The exact causes of cluster headaches is not known. Unlike other primary headache disorders, cluster headaches are not generally associated with triggers such as stress or hormonal changes. However, patterns suggest a link to abnormalities in the body's biological clock.
Medication overuse headache
When medications are used on a regular or long-term basis, people can experience a medication overuse headache or 'rebound headache', which can prolong or exacerbate the original headache. This kind of headache is a secondary headache disorder that is experienced by 1-2% of the population .
Medication overuse headache has a prevalence of around 1% to 2% in the general population and should be suspected in anyone presenting with chronic headache (headache >14 days per month). - Pain Rep. 2017 Jul; 2(4): e612. 
Symptoms of medication overuse headaches often depend on the kind of original headache and the type of medicine used. However, they typically occur daily or near daily, improve with painkillers initially before returning once the medication wears off.
Other symptoms may include:
difficulties with concentration or memory.
[Prescription or over-the-counter medications used to control pain] may decrease the intensity of the pain for a few hours; however, they appear to feed into the pain system in such a way that chronic headaches may result. - National Health Foundation, 2007 
What treatment options exist for headaches?
In some cases, a headache may indicate a condition that requires immediate emergency treatment. Consider seeking such treatment if you experience:
A very severe and sudden headache
A headache after a head injury or fall
A headache accompanied by symptoms such as: confusion, double vision, fever, rash, seizure, weakness, numbness or difficulty speaking.
In many cases, typical headaches can be relieved through simple home remedies and self-action, such as:
ensuring you get sufficient water, food, exercise and rest (particularly when suffering from 'flu or cold)
relieving stress through relaxation
avoiding alcohol, eye-strain (through prolonged looking at a screen) and oversleeping .
The most common over-the-counter medications that people take to treat headaches are painkillers, including paracetamol, aspirin and ibuprofen.
However, as with all medications, care must be taken to carefully follow the instructions and dosage recommendations. As described above, overuse of painkillers can lead to a secondary medication overuse headache or 'rebound headache' that prolongs or exacerbates the original headache.
Chiropractic care is a non-medication means of relieving pain from headaches. Current evidence suggests that chiropractic care can be an effective treatment for migraine and headaches that originate from the neck .
"Evidence suggests that chiropractic care, including spinal manipulation, improves migraine and cervicogenic headaches." - Manipulative Physiol Ther. 2011;34(5):274-89. 
During an initial consultation, chiropractors are able to assess, diagnose and subsequently treat headaches through a range of treatment methods including:
soft tissue therapy
physical modalities, including dry needling, electrical stimulation and ultrasound
providing lifestyle advice.
1. World Health Organization. Headache Disorders. https://www.who.int/news-room/fact-sheets/detail/headache-disorders
2. National Institute of Neurological Disorders and Stroke. Headache: Hope through Research. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Headache-Hope-Through-Research#3138_5
3. National Health Service (UK). Headaches. https://www.nhs.uk/conditions/headaches/
4. "Preventing and treating medication overuse headache", Karl B. Alstadhaug, Hilde K. Ofte, Espen S. Kristoffersen. Pain Rep. 2017 Jul; 2(4): e612. Published online 2017 Jul 26. doi: 10.1097/PR9.0000000000000612
5. National Health Foundation (US). Analgesic Rebound (Medication Overuse Headache). https://headaches.org/2007/10/25/analgesic-rebound-also-known-as-medication-overuse-headache/
6. Bryans R, Descarreaux M, Duranleau M, Marcoux H, Potter B, Ruegg R, Shaw L, Watkin R, White E. Evidence-based guidelines for the chiropractic treatment of adults with headache. J Manipulative Physiol Ther. 2011;34(5):274-89.